找一些关于爆炸载荷缩比等效的论文

The response of masonry structures to explosions can be hardly investigated relying only on numerical and analytical tools. Experimental tests are of paramount importance for improving the current comprehension and validate existing models. However, experiments involving blast scenarios are, at present, partial and limited in number, compared to tests under different dynamic conditions, such as earthquakes. The reason lies on the fact that full-scale blast experiments present many difficulties, mainly due to the nature of the loading action. Experiments in reduced-scale offer instead greater flexibility. Nevertheless, appropriate scaling laws for the response of masonry structures under blast excitations are needed before performing such tests. We propose here new scaling laws for the dynamic, rigid-body response and failure modes of masonry structures under blast loads. This work takes its roots from previous studies, where closed-form solutions for the rocking response of slender blocks due to explosions have been derived and validated against numerical and experimental tests. The proposed scaling laws are here validated with detailed numerical simulations accounting for combined rocking, up-lifting, and sliding mechanisms of monolithic structures. Then, the application to multi-drum stone columns is considered. In particular, we show that, whilst the presence of complex behaviors, such as wobbling and impacts, similarity is assured. The developments demonstrate their applicability in the design of reduced-scale experiments of masonry structures.

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Chemical explosions create blast waves with large overpressure disturbances. It is important to develop a standard blast model based on data to accurately predict acoustic blast-wave amplitudes near detonations and invert for explosion energy from distant observations of blast-wave signals. However, open data from large, controlled chemical explosions with reliable ground truth can be challenging to find. The lack of access to such data could limit the number of contributions to related research and potentially stifle the rate of discoveries or validation of existing models. To address these data scarcity problem, we have curated and compiled a standardized set of 817 blast-wave waveforms from 19 distinct high-explosive events. The blast-wave waveforms are standardized to a 1 kg trinitrotoluene explosion using scaling laws and corrections for location effects. A brief overview of the dataset is presented along with explosion feature models as well as recommendations for extracting explosion features. The resulting dataset is distributed to an open repository in both Seismic Analysis Code and pandas DataFrame formats containing the waveforms, the scaled distances, and the sample rates.

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Despite years of research, it is still unknown whether the interaction of explosion-induced blast waves with the head causes injury to the human brain. One way to fill this gap is to use animal models to establish “scaling laws” that project observed brain injuries in animals to humans. This requires laboratory experiments and high-fidelity mathematical models of the animal head to establish correlates between experimentally observed blast-induced brain injuries and model-predicted biomechanical responses. To this end, we performed laboratory experiments on Göttingen minipigs to develop and validate a three-dimensional (3-D) high-fidelity finite-element (FE) model of the minipig head. First, we performed laboratory experiments on Göttingen minipigs to obtain the geometry of the cerebral vasculature network and to characterize brain-tissue and vasculature material properties in response to high strain rates typical of blast exposures. Next, we used the detailed cerebral vasculature information and species-specific brain tissue and vasculature material properties to develop the 3-D high-fidelity FE model of the minipig head. Then, to validate the model predictions, we performed laboratory shock-tube experiments, where we exposed Göttingen minipigs to a blast overpressure of 210 kPa in a laboratory shock tube and compared brain pressures at two locations. We observed a good agreement between the model-predicted pressures and the experimental measurements, with differences in maximum pressure of less than 6%. Finally, to evaluate the influence of the cerebral vascular network on the biomechanical predictions, we performed simulations where we compared results of FE models with and without the vasculature. As expected, incorporation of the vasculature decreased brain strain but did not affect the predictions of brain pressure. However, we observed that inclusion of the cerebral vasculature in the model changed the strain distribution by as much as 100% in regions near the interface between the vasculature and the brain tissue, suggesting that the vasculature does not merely decrease the strain but causes drastic redistributions. This work will help establish correlates between observed brain injuries and predicted biomechanical responses in minipigs and facilitate the creation of scaling laws to infer potential injuries in the human brain due to exposure to blast waves.

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BackgroundThis work expands upon a previously developed exercise dynamic physiology model (DPM) with the addition of an anatomic pulmonary system in order to quantify the impact of lung damage on oxygen transport and physical performance decrement.MethodsA pulmonary model is derived with an anatomic structure based on morphometric measurements, accounting for heterogeneous ventilation and perfusion observed experimentally. The model is incorporated into an existing exercise physiology model; the combined system is validated using human exercise data. Pulmonary damage from blast, blunt trauma, and chemical injury is quantified in the model based on lung fluid infiltration (edema) which reduces oxygen delivery to the blood. The pulmonary damage component is derived and calibrated based on published animal experiments; scaling laws are used to predict the human response to lung injury in terms of physical performance decrement.ResultsThe augmented dynamic physiology model (DPM) accurately predicted the human response to hypoxia, altitude, and exercise observed experimentally. The pulmonary damage parameters (shunt and diffusing capacity reduction) were fit to experimental animal data obtained in blast, blunt trauma, and chemical damage studies which link lung damage to lung weight change; the model is able to predict the reduced oxygen delivery in damage conditions. The model accurately estimates physical performance reduction with pulmonary damage.ConclusionsWe have developed a physiologically-based mathematical model to predict performance decrement endpoints in the presence of thoracic damage; simulations can be extended to estimate human performance and escape in extreme situations.

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Explosions in an urban setting can have a significant negative impact. There is a need to further understand the loading effects caused by the blast’s interaction with structures. In conjunction with this, the effects of scaling and understanding the limitations of laboratory experiments are equally important given the cost incurred for full-scale experiments. The aim of this study was to determine the scaling effects on blast wave parameters found for reduced-scale urban blast scenario laboratory experiments. This paper presents the results of numerical modelling and physical experiments on detonating cuboidal PE-4 charges and measuring the pressure in direct line of sight and at three distinct positions around the corner of a small-scale “building” parallel to the rear wall. Two scales were used, namely 75% and 100%. Inter-scaling between 75% and 100% worked fairly well for positions shielded by the corner of the wall. Additionally, the lab-scale results were compared to similar (but not identical) field trials at an equivalent scale of 250%. The comparison between lab-scale idealised testing and the larger-scale field trials published by Gajewksi and Sielicki in 2020, indicated sensitivity to factors such as detonator positioning, explosive material, charge confinement/mounting, building surface roughness, and environment.

Since the inception of high explosives as an industrial tool, significant efforts have been made to understand the flow of energy from an explosive into its surroundings to maximize work produced while minimizing damaging effects. Many tools have been developed over the past century, such as the Hopkinson–Cranz (H-C) Scaling Formula, to define blast wave behavior in open air. Despite these efforts, the complexity of wave dynamics has rendered blast wave prediction difficult under confinement, where the wave interacts with reflective surfaces producing complex time-pressure waveforms. This paper implements two methods to better understand blast overpressure propagation in a confined tunnel environment and establish whether scaled tests can be performed comparatively to costly full-scale experiments. Time–pressure waveforms were predicted using both a 1:10 scaled model and three-dimensional air blast simulations conducted in Ansys Autodyn. A comparison of the reduced scale model simulation with a full-scale blast simulation resulted in self-similar overpressure waveforms when employing the H-C scaling model. Experimental overpressure waveforms showed a high level of correlation between the reduced scale model and simulations. Additionally, peak overpressure, duration, and impulse values were found to match within tolerances that are highly promising for applying this methodology in future applications. Using this validated relationship, the simulated model and reduced scale tests were used to predict an overpressure waveform in a full-scale underground mine opening to within 2.12%, 2.91%, and 7.84% for peak overpressure, time of arrival, and impulse, respectively. This paper demonstrates the effectiveness of scaled, blast models when predicting blast wave parameters in a confined environment.

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Various accidental explosions and terrorist attacks have occurred frequently, posing a huge threat to the safety of building structures. To enhance the safety of building structures, the finite element model of a reinforced concrete column was established by ANSYS / LS-DYNA finite element analysis software. By comparing with the experimental results, the accuracy of the finite element model was verified, and the failure mode of reinforced concrete columns under different scaled distances was analyzed. The effects of four damage factors: charge weight, axial load ratio(ALR), concrete compressive strength, and stirrup ratio on the dynamic response of column damage were analyzed. Based on the dimensional analysis Π theory, the dimensionless relationship between the damage coefficient of the column based on the residual axial bearing capacity and the explosion scaled distance is obtained. Based on a large number of numerical simulation results, a damage assessment method for reinforced concrete columns subjected to explosion loads is proposed, utilizing dimensional analysis theory. The results show that with the increase of scaled distance, the failure mode of the column will gradually change from brittle shear failure to plastic bending failure. Increasing the axial load ratio, concrete compressive strength and, stirrup ratio, and reducing the charge weight can reduce the damage to the column and improve the blast-resistant performance of the column. It is verified that the proposed dimensionless prediction relationship can better predict the damage degree of reinforced concrete columns at different scaled distances, to provide some reference for the field of structural blast-resistant.

The displacement response of a cylindrical and an apsidal shaped structural unit under blast loading is compared in this study using the finite element code LS-DYNA utilizing two different concrete constitutive models, namely the Riedel–Hiermaier–Thoma (RHT) model and the Continuous Surface Cap Model (CSCM). The blast load generated by an emulsion explosive corresponding to six scaled distances is used for the study. The validation of the displacement response is carried out by utilizing the Newmark numerical integration procedure using the linear acceleration method. The unique apsidal shape in its displacement response performs better across all the simulations indicating superior blast resistance. CSCM model returns conservative values of displacements in the study. The study finds that the RHT model requires higher stress levels for consideration of dynamic strengths and hence returns lower displacement values for the instances considered in this simulation. This study recommends the use of an apsidal unit and the use of RHT constitutive model in the simulations.

This study investigates the failure modes and damage extent of reinforced concrete (RC) columns under the combined action of eccentric blast loading and axial compressive loading through experimental tests and numerical simulations. Field blast tests were performed using half-scaled-down models for close-in airburst tests. The effects of charge mass, explosive position, and axial load on the failure modes and damage levels of RC columns under close-range blast loading were investigated. Eight experimental datasets of blast overpressure were obtained, and curve fitting was performed on these data to establish an empirical formula, thereby enhancing the predictive accuracy of blast effect assessment in practical engineering scenarios. The test results indicated that when the explosive position is closer to the column base, the structural failure mode becomes closer to shear failure. To further interpret the experimental data, a detailed finite element model of RC columns was developed. Numerical simulations of RC columns were conducted using the RHT model. The rationality of the model was validated through comparison with experimental data and the SDOF method, with dynamic response analyses performed on cross-sectional dimensions, the longitudinal reinforcement ratio, the scaled distance, the explosion location, and axial compression. An empirical formula was ultimately established to predict the maximum support rotation of RC columns. Studies have shown that when the explosive position is closer to the column base, the structural failure mode approaches shear failure, and axial compression significantly increases the propensity for shear failure.

With the evolution of modern warfare and the increased use of improvised explosive devices (IEDs), there has been an increase in blast-induced traumatic brain injuries (bTBI) among military personnel and civilians. The increased prevalence of bTBI necessitates bTBI models that result in a properly scaled injury for the model organism being used. The primary laboratory model for bTBI is the shock tube, wherein a compressed gas ruptures a thin membrane, generating a shockwave. To generate a shock wave that is properly scaled from human to rodent subjects many pre-clinical models strive for a short duration and high peak overpressure while fitting a Friedlander waveform, the ideal representation of a blast wave. A large variety of factors have been experimentally characterized in attempts to create an ideal waveform, however we found current research on the gas composition being used to drive shock wave formation to be lacking. To better understand the effect the driver gas has on the waveform being produced, we utilized a previously established murine shock tube bTBI model in conjunction with several distinct driver gasses. In agreement with previous findings, helium produced a shock wave most closely fitting the Friedlander waveform in contrast to the plateau-like waveforms produced by some other gases. The peak static pressure at the exit of the shock tube and total pressure 5 cm from the exit have a strong negative correlation with the density of the gas being used: helium the least dense gas used produces the highest peak overpressure. Density of the driver gas also exerts a strong positive effect on the duration of the shock wave, with helium producing the shortest duration wave. Due to its ability to produce a Friedlander waveform and produce a waveform following proper injury scaling guidelines, helium is an ideal gas for use in shock tube models for bTBI.

In recent years, the number of casualties caused by improvised explosive devices (IEDs) in conflict zones has increased. To protect occupants from the large accelerations generated by explosions, the development of blast shock-absorbing seats is considered necessary. Before developing such seats, it is essential to study the motion of the vehicle body subjected to impacts from below. To reduce significant time and costs, a seesaw experiment is conducted on a scaled-down vehicle body model, referred to as the vehicle body model. Preliminary experiments showed that the displacement of the vehicle body model in the seesaw experiment was similar to that in the explosion experiment, but the acceleration wave had a longer duration and a smaller peak acceleration. This is thought to be due to the deflection of the seesaw plate when applying impact to the vehicle body model in the seesaw experiment. Therefore, the seesaw plate was modified to a U-shape to reduce deflection, allowing the seesaw experiment to be conducted. However, the increased mass of the seesaw plate resulted in an increased moment of inertia, which hindered the rotational motion of the seesaw.

It is crucial to improve the calculation efficiency of internal blast loads of a long-span spatial steel structure. This study develops an equivalent model for such loads using a one-way inclined single-layer cylindrical lattice shell structure as a case study. First, ANSYS/LS-DYNA was used to simulate free-air blasts and benchmark against experimental data, with peak overpressure errors below 8%, confirming the modeling approach and material parameters. Next, a numerical model of the cylindrical lattice shell structure under internal explosion was generated via the same modelling method and material parameters. The simulation results indicated that the internal explosion overpressure differed from that of free-air blasts, exhibited pronounced reflection and convergence effects, and was no longer related to the scaled distance. On this basis, an equivalent model combining a standard overpressure distribution with correction factors for reflection and convergence was formulated. Validation against two additional case studies demonstrated that the model provides conservative predictions, with average errors of 9.38% and 7.47% relative to detailed simulations. The proposed equivalent model therefore offers a rapid, reliable tool for the preliminary assessment of internal blast loads in similar spatial structures.

In scale-down tests of ship structures subjected to a blast load, the accuracy of the predicted response of a prototype is affected by the material substitution and geometric distortion between a scaled model and a full-size structure; this is known as incomplete similarity. To obtain a more accurate response from a prototype during small-size tests, a corrected method for scaling the response of thin plates and stiffened plates under a blast load was derived. In addition, based on numerical simulations of explosion responses by employing the elastic–plastic model and the Johnson–Cook constitutive model, it was found that using the average yield stress derived from the equivalent plastic strain energy in the ideal elastic–plastic model can obtain consistent structural responses. Moreover, a method for calculating the distortion factor caused by the yield stress of different materials was proposed. Furthermore, it was demonstrated that the average effective plastic strain between the prototype and the corrected model is equal, and based on this, a similarity prediction method was established to correct the distortions caused by yield stress and the thickness of blast loaded plates. The results indicate that the proposed correction method can compensate for the differences caused by distorted factors of yield stress and thickness, with the maximum error in the structure’s peak displacement being less than 3%.

No abstract available

With the development of human society, various accidental explosions and terrorist attacks have occurred frequently, posing a great threat to the safety of building structures. In order to improve the safety of building structure, the finite element model of reinforced concrete slab was established by ANSYS/LS-DYNA finite element analysis software. By comparing with the experimental results, the accuracy of the established finite element model was verified, and the failure modes of reinforced concrete slab under different scaled distances were analyzed. The effects of three damage factors: concrete compressive strength, protective layer thickness and reinforcement ratio on the dynamic response of the slab were analyzed. Based on the Π theory of dimensional analysis, the dimensionless relationship between the peak displacement of the mid-span of the plate and the scaled distance of the explosion is obtained. On the basis of a large number of numerical simulation results, the dimensionless relationship for quickly predicting the dynamic response of the plate is summarized. The results show that with the increase of scaled distance, the failure mode of the plate will gradually change from brittle shear failure to plastic bending failure. Increasing the compressive strength and reinforcement ratio of concrete and reducing the thickness of the protective layer can reduce the peak displacement of the mid-span of the slab and improve the anti-explosion performance of the slab. It is verified that the proposed dimensionless prediction relationship can better predict the dynamic response of reinforced concrete slabs at different scaled distances, so as to provide some reference for the field of structural anti-explosion.

With the rapid development of computer hardware and software technology, numerical simulations have become one of the most important tools for studying propagation law of blast wave. Results of numerical simulations of explosion events greatly depend on the mesh size. The mesh size determination methods in the literature are relatively weak in generality. In this paper, a mesh size determination method with strong applicability is proposed. According to this method, the mesh size is the product of the scale coefficient and the third root of the equivalent TNT mass. The scale coefficient is related to the model dimension, scaled distance and simulation accuracy, and is independent of the TNT shape and the location of the detonation point. A large number of numerical simulation results confirm the accuracy of this method. The recommended scale coefficient to meet the engineering accuracy requirements is related to the model dimension and scaled distance. In general, when the scaled distance and model dimension are larger, the recommended scale coefficient will be larger. In this paper, the figures and tables of the recommended scale coefficients of 1D, 2D and 3D models varying with the scaled distance are given, and their rationality is verified by the existing numerical simulation events of blast wave. They can be used as a reference to determine the mesh size in numerical simulation of blast wave.

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Public buildings that house large populations are easy targets for terrorist attacks, the primary issue of architectural blast-resistant design is how to get blast loads on the surface of structures, and the shapes of blast waves and buildings both have important effects on it. In this paper, experiments and numerical simulations were carried out on blast loads on the surface of the cylindrical shell. blast loads, detonation products, and blast waves were well recorded and simulated, blast loads at the edge of cylindrical shells were attenuated by about 75%, and vortex rings were accidentally photographed nearby. blast loads are much affected by the location of the detonation point, charge shape, and charge size. The original shape of structures rather than deformation determines the distribution of blast loads, the air viscosity also needs to be scaled when using a scaled model to test blast loads. Experimental and simulation methods can offer a reference for building a standard database of blast loads.

Recently, polyurea has been applied to improve the anti-blast performance of metal plates, masonry walls, and concrete structures. However, the strengthening effectiveness of polyurea on ultra-high performance concrete (UHPC) slabs with an overall response is still unclear. Hence, this paper examined the strengthening effectiveness of polyurea on the anti-blast performance of UHPC slabs under near-field explosion by the finite element (FE) method. First, a benchmark finite element model for UHPC and polyurea-UHPC (PUHPC) slabs under blast loading was established and validated by field blast tests, with scaled distances ranging from 0.4 m/kg1/3 to 0.8 m/kg1/3. After that, parametric analysis was conducted to fully understand the strengthening effectiveness of polyurea on the anti-blast performance of the UHPC slab. Factors including the scaled distance, polyurea thickness, span-to-depth ratio of the slab, and longitudinal reinforcement ratio were considered. The results showed that (1) spraying polyurea on the rear face of the UHPC slab can reduce the width of cracks and mitigate the damage of specimens; (2) the strengthening effectiveness of polyurea on the UHPC slab became prominent when the UHPC slab suffered a larger maximum deflection; (3) in terms of the deflection and energy absorption capacity of PUHPC slabs, the optimum thickness of sprayed polyurea was determined to be 8 mm to 12 mm; and (4) by adopting the multiple nonlinear regression method, a prediction formula was developed to quickly obtain the end rotation of the UHPC slab strengthened with polyurea under near-field explosions.

Experiments and numerical simulations were performed to investigate the blast resistance of concrete beams reinforced with ultra-high-molecular-weight polyethylene (UHMWPE) fibers under close-in blast loads. The blast tests were carried out on fiber- reinforced concrete beams with a volume content of 0.7% at three scaled distances (i.e., 0.36, 0.40, and 0.47 m/kg1/3) and the damage results were compared with the characteristics of normal reinforced concrete beams. The results show that the UHMWPE fibers can decrease the damage degree of the beams, hinder the generation and development of cracks, and prevent spalling on the back surface, indicating that the blast resistance of UHMWPE-fiber-reinforced concrete beams is better than that of normal reinforced concrete beams with the same strength grade. Due to the addition of fibers, the improvement in the damage resistance to blast loads at the bottom surface of the beam is better than that at the top surface. A 3D blast-test model was established and calculated using the LS-DYNA software. A numerical study of the extended scaled distances was carried out to determine the change law of the damage features based on it. When the scaled distance is greater than 0.41 kg/m1/3, the damage mode of the beam begins to change from the mode of large damage at the bottom and small damage at the top to the mode involving large damage at the top and small damage at the bottom.

The submarine H.L. Hunley was the first submarine to sink an enemy ship during combat; however, the cause of its sinking has been a mystery for over 150 years. The Hunley set off a 61.2 kg (135 lb) black powder torpedo at a distance less than 5 m (16 ft) off its bow. Scaled experiments were performed that measured black powder and shock tube explosions underwater and propagation of blasts through a model ship hull. This propagation data was used in combination with archival experimental data to evaluate the risk to the crew from their own torpedo. The blast produced likely caused flexion of the ship hull to transmit the blast wave; the secondary wave transmitted inside the crew compartment was of sufficient magnitude that the calculated chances of survival were less than 16% for each crew member. The submarine drifted to its resting place after the crew died of air blast trauma within the hull.

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Explosive field trials have been conducted to measure the peak incident pressure, impulse and time of positive phase duration following the detonation of 15 different masses of the Plastic Explosive No #4. A novel aspect of these field trials was the repeatability of tests. Eight pressure gauges collected data during each blast, and at each scaled distance. In all, 4 blasts were conducted for each scaled distance (i.e. up to 32 measurements recorded for each scaled distance) – 60 blasts were fired in total. Consequently, this repeatability of testing allowed the mean and variance of blast pressure–time histories to be quantified, with a view to better characterise the variability of a blast itself and model error variability. This article describes the explosive field trials, and the statistical analysis of blast load variability and model error for peak incident pressure, impulse and time of positive phase duration. It was found that the mean model error is close to unity with a coefficient of variation of up to 0.15 for pressure and 0.21 for impulse. The lognormal probability distribution best fits the model error data. The probabilistic models derived from these tests can be used for a variety of structural engineering applications, such as calculating reliability-based design load or partial safety factors for explosive blast loading, and estimating the probability of damage and casualties for infrastructure subject to explosive blast loading. This is illustrated for a terrorist explosive scenario involving a spherical free-air burst, where the damage modes of interest are breaching and spalling of a concrete slab. It was found that the variability of charge mass, range and model error have a significant effect on reliability-based design.

No abstract available

This paper aims to evaluate how different numerical parameters affect the accuracy and reliability of hybrid smoothed particle hydrodynamics-finite element method (SPH-FEM) simulations for the blast response of full-scale reinforced concrete beams. A numerical study was conducted using LS-DYNA, combining the SPH method to model the explosive and the FEM for the reinforced concrete structure. 81 simulations were performed, varying SPH particle count (800,000; 1.6 million; 3.2 million), FEM mesh size (10, 15 and 20 mm) and concrete models (CSCM, RHT and K&C), across scaled distances ranging from 0.4 to 0.8 m/kg1/3. The results were validated against full-scale experimental data. The study demonstrates that the structural response is non-linearly sensitive to both SPH and FEM parameters. Finer meshes tend to overpredict peak accelerations, as does a reduced number of SPH particles. Contrary to established practice, which advocates the use of a high number of SPH particles, this paper shows that such an approach is not universally valid and that optimal particle density depends on the FEM mesh size employed. This paper focuses on a specific blast setup and geometry, so findings may have limited generalisability. Further research should cover other scaled distances. The paper provides valuable guidance for engineers and researchers using SPH-FEM methods in blast analysis, identifying optimal combinations of mesh size and SPH resolution. This study addresses a gap in the literature regarding the combined effects of SPH and FEM discretisation parameters in blast simulations. Unlike previous works, this research systematically explores their interaction and impact on accuracy and efficiency, providing guidance for future SPH-FEM modelling.

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This article presents the modeling of a vapor cloud explosion [VCE] in t e “ e i s” pipeline loc ted in t e unicip lit o c tepec St te o e ico using t e equivalent TNT method to determine overpressure impact zones. The study is based on a hypothetical event in which a corrosion failure in the pipeline causes a leak, resulting in an unconfined explosion. Energy equivalence equations between methane and TNT were applied to calculate the equivalent mass, overpressure, and affected radii. The results indicate different zones: lethality at 35.2 m [8.0 psi], risk at 145 m [1.0 psi], and attenuation at 247.5 m [0.5 psi]. It is concluded that the model is an effective tool for identifying chemical-technological risks, allowing the establishment of mitigation strategies, emergency plans, and preventive measures in urban environments with critical gas transportation infrastructure.

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In this paper, the design theory of explosion-containment vessel is studied, the charge ratio distance, incident overpressure and reflection overpressure acting on the inner wall of the explosion-containment vessel are calculated when 3kg TNT is exploded in it, the transient load generated in the explosion is converted into equivalent static load by the method of dynamic coefficient, and the main wall thickness of 3kg TNT equivalent explosion-containment vessel is determined. A 3kg TNT equivalent capsule explosion-containment vessel is designed and tested the explosion performance, the explosion performance test results show that the design of the 3kg TNT equivalent explosion-containment vessel is reasonable, safe and reliable, and it is of great practical significance to apply it to the transportation and destruction of weapons and ammunition and emergency treatment.

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: In response to the lack of design data for explosive charges greater than 100 kg trinitrotoluene (TNT) in the current Design Code for Blast-Resistant Structures (GB 50907—2013), the study utilized the explicit finite element software LS-DYNA to simulate the dynamic responses of blast-resistant chambers under large-equivalent explosion scenarios. A parametric analysis was conducted on various design parameters to investigate their impacts on the structural performance of the blast-resistant chamber, and design recommendations were proposed. Firstly, the accuracy of the simulation model was verified by comparing the finite element results with existing blast test data, showing errors of 4. 7%, 12. 9%, and 2. 3% for panels P2-1, P2-2, and P2-3, respectively. Secondly, the study analyzed the stress variations in the blast-resistant chamber under the equivalent of 100 - 200 kg TNT, revealing that when the TNT equivalent reached 160 kg, the wall reinforcement entered the plastic deformation stage. Based on this, further analysis was carried out to assess the effects of different design parameters on the load-bearing capacity of the blast-re-sistant chamber at the 160 kg TNT equivalent. The results indicated that within the range of 100 kg to 200 kg TNT, plastic zones initially formed in the tensile region at the base of the sidewalls and gradually expanded outward. The wall panel connections emerged as the primary areas of stress concentration. Based on the analysis, it was recommended that the wall thickness of the blast-resistant chamber should be be-tween 600 mm and 900 mm, with the concrete strength not lower than C50, the rebar yield strength not less than 300 MPa, and the rebar diameter not smaller than 22 mm. The reinforcement ratio for the walls should exceed 0. 3%, and haunched diagonal rebars at the wall panel connections should be chosen at 4 / 5 of the main rebar diameter.

To assess the impact on human health of the sonic boom that occurs when an aircraft is flying at supersonic speed, and, accordingly, to solve the problem of noise reduction by optimizing the aircraft design, it is proposed to evaluate the shock wave energy using the TNT equivalent of a cylindrical explosion. An example of calculating the shock wave energy during flights of F4 and F18 aircraft at different altitudes is considered. To calculate the evolution of an acoustic pulse during its propagation from the boundary of the shock wave transition to the acoustic one, the wave equation and its solution are used, taking into account the inhomogenei-ty of the atmosphere, nonlinear effects, absorption and expansion of the wave front, as well as the results of ground-based measurements of acoustic pulses. The results of calculations of the dependence of the explosion energy on the flight altitude, as well as on the type of aircraft are explained on the basis of the formula for the atmospheric resistance force.

The structure size of the crater formed by the earth-penetrating nuclear bomb explosion is one of the important parameters for evaluating the earth-penetrating nuclear bomb damage power. Obtaining the structure size of the crater formed by the earth-penetrating nuclear bomb explosion with different yields is great significance for the evaluation and design of the nuclear bomb damage power. In this study, considering the contradictory relationship between the structure size of the earth-penetrating nuclear bomb and the structure size of the equivalent TNT mass, we propose to use the equivalent energy mapping method to realize the finite element numerical simulation of the earth-penetrating nuclear bomb exploding into craters analyzed and compared the simulation results with the structure size of the crater formed by the ESS nuclear bomb explosion in the United States. The analysis results show that the error between the simulated crater radius and the real crater radius is 3.26%, and the error between the simulated crater depth and the real crater depth is 28.57 %. It meets the calculation accuracy error range of crater formation from nuclear explosion to chemical explosion. Therefore, this method provides an effective numerical simulation method and a means of obtaining the structural size data of the explosion crater for the earth-penetrating nuclear bomb cratering.

The peak gas pressure developed as a result of a confined explosion is an important parameter characterizing the pressure signal and is crucial for assessment of the structural response of the confined space envelope elements. The gas pressure depends on the amount of the released energy, including the afterburning energy. A new analytical model is presented to predict the gas pressure developed in a confined volume, for different types of explosives, as function of the charge weight (W) and the free confined volume (V), considering the afterburning effect. The model is based on the detonation chemical reaction and on the calculation of a full or partial afterburning energy release due to the reaction of the fuels in the detonation products with the surrounding oxygen. Considering the detonation energy and the possible additional afterburning energy, the model demonstrates the different behavior of the gas pressure variation with W/V for different types of explosives. The equivalent TNT charge weight is calculated for each explosive. According to the analysis performed, the TNT equivalent factor varies with W/V. The predictions of the model results are compared with available models as well as with available test data and very good agreement is obtained.

Reinforced concrete shear wall structures (RCSWs) are commonly used as explosion-resistant chambers for storing hazardous chemical materials and housing high-pressure reaction equipment, serving to isolate blast waves and prevent chain reactions. In this study, full-scale experiments and numerical simulations were conducted to investigate the blast resistance of RC shear wall protective structures subjected to internal explosions. A full-scale RC shear wall structure measuring 9.7 m × 8 m × 6.95 m with a wall thickness of 0.8 m was constructed, and an internal detonation equivalent to 200 kg of TNT was initiated to simulate the extreme loading conditions that may occur in explosion control chambers. Based on experimental data analysis and numerical simulation results, the damage mechanisms and dynamic response characteristics of the structure were clarified. The results indicate that under internal explosions, severe damage first occurs at the wall–joint regions, primarily exhibiting through-thickness shear cracking near the supports. The structural damage process can be divided into two stages: local response and global response. Using validated finite element models, a parametric study was carried out to determine the influence of TNT charge weight and reinforcement configuration on the structural dynamic response. The findings of this research provide theoretical references for the design and strengthening of blast-resistant structures.

With the increasing demand and import of liquefied natural gas (LNG), large LNG receiving stations have been built one after another. LNG leakages can lead to fires or explosions in storage tanks. The coupling accident between explosion and fire is inevitable. In this paper, the selected K&C concrete constitutive model is simulated and verified by LS‐DYNA. Based on the verified material body model, it was applied to a large LNG storage tank. A two‐step analysis method (thermal analysis—impact analysis) was used to simulate the whole process of impact of different equivalent TNT on a large LNG storage tank at 800°C. The results show that under the combined action of high temperature and bidirectional load equivalent to 500 kg TNT, the center of the tank roof is damaged. Under the combined action of high temperature and two‐way load equivalent to 800 kg TNT, the entire tank roof was destroyed, and the maximum expansion deformation distance at the top of the tank reached 137.9 mm. The research results can provide theoretical reference for the safety design of storage tank under impact and high temperature, enhance the bearing capacity of outer tank and improve the safety of tank farm.

Maritime safety is crucial as vessels underpin global trade, but engine room explosions threaten crew safety, the environment, and assets. With modern ship designs growing more complex, numerical simulation has become vital for analyzing and preventing such events. This study examines safety risks from alternative fuel explosions in ship engine rooms, using the Trinitrotoluene (TNT)-equivalent method. A finite element model of a double-layer cabin explosion is developed, and simulations using blastFOAM in OpenFOAM v9 analyze shock wave propagation and stress distribution. Four explosion locations and five scales were tested, revealing that explosion scale is the most influential factor on shock wave intensity and structural stress, followed by equipment layout, with location having the least—though still notable—impact. Near the control room, an initial explosion caused a peak overpressure of 2.4 × 106 Pa. Increasing the charge mass from 10 kg to 50 kg raised overpressure to 3.9 × 106 Pa, showing strong dependence of blast intensity on explosive mass. Equipment absorbs and reflects shock waves, amplifying localized stresses. The findings aid in optimizing engine room layouts and improving explosion resistance, particularly for alternative fuels like liquefied natural gas (LNG), enhancing maritime safety and sustainability.

Designing reliable protective structures or individual structural elements requires a comprehensive analysis of the stress–strain behavior of their components within the “foundation–protective structure” system under various types of loading. It is essential to consider multiple input parameters that directly influence the calculation results. This study presents the results of numerical simulations assessing the effect of a projectile with a mass of 300 kg and a velocity of 60 m/s striking a fragment of a protective wall. The projectile’s attack angle relative to the horizontal varied and took the following values: 0°, 15°, 45°, and 60°. Additionally, the effect of detonation of a warhead containing approximately 100 kg of explosive (TNT equivalent) was analyzed. The calculations were performed using the ANSYS/LS-DYNA software package. The wall fragment has a thickness of 1200 mm and is supported by shallow foundations. The wall is reinforced with four layers of steel bars of varying diameters and variable spacing. The roof of the protective structure is a multilayer reinforced concrete slab resting on steel beams. In developing the numerical model of the “foundation–protective structure” system, the Lagrangian method was used. The geometry of the wall, roof, foundation, and soil was modeled with solid elements, while the discrete reinforcement of the reinforced concrete components was modeled using beam elements. To simulate the explosion, a Lagrangian–Eulerian approach was applied. The explosive material was defined physically, and its behavior was described by an equation of state. The analysis of projectile impact on the wall fragment of the protective structure revealed that changes in the projectile’s attack angle have a significant effect on the extent and pattern of structural damage. The difference between the damaged areas for attack angles of 0° and 60° reaches up to 70%, while the variation in reinforcement stress values is 20% and 73% for the outer and inside faces of the wall, respectively. The study also demonstrates the nature of wall damage caused by the explosion. On the outer face, the damage is distributed, whereas on the inside face, it is concentrated in the central region. The area of plastic deformation zones is 41% larger for the outer and 18% larger for the inside face compared to those caused by projectile impact at an attack angle of 0°. The reinforcement stresses reach ultimate values of up to 500 MPa. Under combined effects, the explosion has a significantly greater impact on the protective structure wall, while the attack angle has a negligible influence.

This article investigates the validity of current forensic practices to analyze an explosion event. The purpose of this study is to use forensic engineering techniques with the integrated models for the simulation of blast fragments and blast pressure to determine an explosive weight used in a bombing incident and later predict a lethal radius caused by blast pressure and a lethal zone caused by fragment impact. The real explosion incident at the Erawan shrine in central Bangkok on August 17, 2015, is selected as a case study. By comparing the structural damage at the blast site to the one obtained from finite element (FE) analyses, an estimated bare charge weight of TNT used in the incident can be obtained. It was found that an estimated bare charge of 3 kg TNT equivalent could have been used for the bomb. To confirm the validity of the calculated explosive weight, a combined lethal zone from blast pressure and scattered fragments was analyzed. Human damage due to the blast pressure is analyzed based on Bowen's lethality curves. The lethality zone from expelled fragments is drawn based on a 50% probability of lethality, which considers the hit density and kinetic energy of the fragment. The analyzed lethal zone agrees reasonably well with the actual observed human damage level. The proposed forensic engineering technique offers the potential for enhancing management and policies in homeland security, contributing to a safer community.

In this study, the overpressure and impulse distribution characteristics of high-pressure hydrogen tank explosions were analyzed using simplified models and computational analysis. Two simplified models, Molkov’s model and the TNT-equivalent method, were employed, and a computational analysis was conducted using the OpenFOAM code with the Reynolds-averaged Navier–Stokes approach. The pressure wave propagated spherically during the explosion of the high-pressure hydrogen tank. However, the interaction with the ground generated a reflected overpressure, which had a significant influence on the radial overpressure distribution. Furthermore, the high-temperature flame region was confined to the vicinity of the explosion source, and the flame was identified as a diffusion flame. The simplified models predicted the maximum overpressures in the radial and axial directions. As the simplified models treat the hydrogen tank as a point source, they predict the same overpressure and impulse values in both the radial and axial directions, which can limit the accuracy of real high-pressure hydrogen tanks with large aspect ratios (length-to-diameter ratios). Computational fluid dynamics analysis showed reasonable agreement for the maximum overpressure of the experimental results in both the radial and axial directions. However, the accurate modeling of the reflected overpressure, particularly at close distances, is critical to improving the prediction accuracy for overpressure and impulse distributions.

In this study, the risks were investigated by probabilistic analysis of the effects on the person and structure located around the composite solid propellant when it explodes abnormally. Two types of solid propellants of different sizes and three TNT equivalents of composite propellants were applied to empirical correlation to derive incident pressure and impulse. These were used in probit analysis, and the effects on the person and structure were quantitatively analyzed to determine the risk of solid propellant explosion. The larger the propellant and the more the TNT equivalent, the higher the incident pressure and impulse. Moreover, the amount of propellant had a more significant effect on the impulse than the incident pressure. The effects of the incident pressure and impulse on human were observed to be greater in the order of probability of ruptured eardrums, death from head impact, death from whole-body displacement impact, and death from lung damage. Furthermore, the effects on the structure were observed to be greater in the order of probability of breakage of window, minor damage, major damage, and collapse of the building.

The use of earth-covered magazines (ECMs) is increasingly prevalent in protective engineering due to their concealment and cost-effectiveness. To explore the optimal thickness of earth covering for ECMs, scaled model tests were conducted under explosive charges equivalent to 30 kilograms of TNT. The resulting overpressure outside the model in the 180° direction was measured. Subsequently, computational analyses were conducted employing LS-DYNA software to examine these experimental findings. The findings indicate that increasing the thickness of the rear soil can mitigate peak overpressure, delay the air shock wave’s arrival time, and reduce the impulse of the positive phase. The numerical calculations closely align with experimental data, with peak overpressure deviation remaining under 10%. The shock wave initially impacts the top of the model before reaching the rear, with soil scattering more pronounced in the 90° direction compared to the 180° direction. Furthermore, an analysis of soil energy absorption rate variation was conducted based on energy conservation principles. These results provide valuable insights for optimizing the design and construction of ECMs.

After the explosion of the warhead shell fragments will consume a portion of the charge release energy, a method of calculating the shockwave overpressure value of the explosion of the warhead is to calculate the shockwave overpressure value by firstly converting the actual charge C of the warhead into the charge CEB of the bare charge, and then converting CEB into TNT equivalent. Experimental results were used to compare the calculation error size of the two models for calculating the equivalent bare charge of the warhead, and the results show that the calculation results of Chi Jiachun's modified model are in better conformity with the experimental results; by analyzing the influence of the empirical constant in Chi Jiachun's modified model on the calculation results, the value of the empirical constant is given as a suggestion.

Amid the ongoing global warming crisis, there has been growing interest in hydrogen energy as an environmentally friendly energy source to achieve carbon neutrality. A stable and large-scale hydrogen storage infrastructure is essential to satisfy the increasing demand for hydrogen energy. Particularly for hydrogen refueling stations located in urban areas, technological solutions are required to ensure the stability of adjacent civil structures in the event of hydrogen storage tank explosions. In this study, a numerical analysis using equivalent trinitrotoluene (TNT) and Concrete Damage Plasticity (CDP) models was employed to analyze the dynamic behavior of the ground in response to hydrogen gas explosions in shallow underground hydrogen storage facilities and to assess the stability of nearby structures against explosion effects. According to the simulation results, it was possible to ensure the structural stability of nearby buildings and tunnel structures by maintaining a minimum separation distance. In the case of nearby building structures, a distance of at least 6 to 7 m is needed to be maintained from the underground hydrogen storage facility to prevent explosion damage from a hydrogen gas explosion. For nearby tunnel structures, a distance of at least 10 m is required to ensure structural stability.

Introduction: Seismic waves generated by shallow underground explosions propagate differently from those generated by surface explosions. Thus, an accurate understanding of the propagation laws of seismic waves generated by explosions at various burial depths and TNT equivalent amounts is significant in assessing the destructive power of munitions and establishing guidelines for their application.Methods: In this study, we conducted several ground vibration velocity tests of shallow underground chemical explosion seismic waves for various TNT equivalent amounts and burial depths in a shooting range and analyzed the propagation of the seismic waves. Using the explosion similarity theory and dimensional analysis, we derived an equation for the estimation of the particle vibration velocity of shallow underground chemical explosion seismic waves. This equation calculation results have a very high degree of agreement with the measured data, measured data verify that the accuracy of the calculation model is better than 90.2%.Results and discussion: This equation calculation results have a very high degree of agreement with the measured data, measured data verify that the accuracy of the calculation model is better than 90.2%, which greatly improves the calculation accuracy of the shallow underground chemical explosion seismic wave particle vibration velocity, and thus provide effective theoretical support for analyzing explosion seismic waves in engineering tests.

In recent years, the exceptional performance of steel fiber-reinforced concrete in blast and impact resistance has garnered widespread recognition, sparking considerable interest in its practical application in small box girders. To this end, nine groups of Trinitrotoluene (TNT) explosion simulation experiments were designed with the equivalent magnitudes matching those of actual automobile explosions to evaluate the anti-explosion and anti-penetration capabilities of steel fiber-reinforced concrete and ordinary concrete using the Arbitrary Lagrangian-Eulerian (ALE) method and the Smoothed Particle Hydrodynamics-ALE method. The aim was to explore the application prospects of steel fiber-reinforced concrete in small box girders. The research results demonstrate that with increasing TNT equivalent, the leading cause of breach to concrete slabs changes from spalling to cratering. The penetration resistance of steel fiber-reinforced concrete slabs is superior to its blast resistance. However, when the explosive force is larger than the sedan, the anti-explosion effect of steel fiber-reinforced concrete slabs becomes negligible. Moreover, under typical automobile explosion loads, the addition of 2% steel fibers can reduce spalling by up to 23% and cratering by up to 13% and can decrease the area of penetration damage by up to 47%. In designing blast-resistant structures, steel fiber-reinforced concrete is not recommended to enhance the blast resistance of bridges when the TNT equivalent exceeds 500 kg.

Explosive shock wave protection is an important issue that urgently needs to be solved in the current military and public security safety fields. Non-metallic protective structures have the characteristics of being lightweight and having low secondary damage, making them an important research object in the field of equivalent protection. In this paper, the numerical simulation was performed to investigate the dynamic mechanical response of non-metallic annular protective structures under the internal blast, which were made by the continuous winding of PE fibers. The impact of various charges, the number of fiber layers, and polyurethane foam on the damage to protective structures was analyzed. The numerical results showed that 120 PE fiber layers could protect 50 g TNT equivalent explosives. However, solely increasing the thickness of fiber layers cannot effectively enhance the protection efficiency. By adding polyurethane foam in the inner layer, the stress acting on the fiber could be effectively reduced. A 30 mm thick polyurethane layer can reduce the equivalent stress of the fiber layer by 41.6%. This paper can provide some reference for the numerical simulations of non-metallic explosion protection structures.

As the main load-bearing component in building structure, the damage of Reinforced Concrete (RC) column determines whether the building structure collapses. In this paper, the influence of column structure and material parameters on the damage of RC columns is analyzed by ANSYS, and the damage degree of RC columns under different equivalent TNT is calculated and analyzed. According to the numerical results, the damage degree laws of RC columns with different parameters are summarized, the consumption process of explosion energy in RC columns is summarized, and the methods to improve the explosion resistance of RC columns are given.

To study the dynamic response and deformation evolution of the rectangular recycled aggregate concrete-filled steel tubular (RRACFST) column under small-equivalent loads and weak disturbances, the measuring methods of blasting and the arrangement of measuring points were precisely handled. Three contact explosion tests were conducted on the RRACFST column to obtain their failure modes, dynamic strains, and accelerations. The research results indicate that the range of 20-30g TNT equivalent represents the starting point and critical point of plastic deformation for the RRACFST column. When the explosive quantity increases incrementally under small-equivalent loads and weak disturbances, the radius and size of the explosion crater do not exhibit a linear relationship. The methods of explosive treatment under small-equivalent loads and weak disturbances adhere to the core principles of precision and quantification, meeting engineering requirements. This study provided a theoretical basis and experimental basis for the safety study of RRACFST columns structure under explosion load.

A novel 316L stainless steel Vertex Modified BCC (VM-BCC) lattice unit cell with attractive performance characteristics is developed. Lattice structure, as well as the sandwich panel, are constructed. Numerical simulation is utilized to simulate the quasi-static compression, dynamic compression and blast behavior considering the rate-dependent properties, elastoplastic response and nonlinear contact. Finite element results are validated by comparing with the experimental results. Parametric studies are conducted to gain insight into the effects of loading velocity, equivalent TNT load and explosion distance on the dynamic behavior of the lattice pattern and sandwich panel. Testing results indicate that the proposed 316L stainless steel VM-BCC structure exhibits more superior plateau stress and specific energy absorption (SEA) than those of the BCC or Octet one. The proposed novel lattice will provide reference for improving the protective efficiency in key equipment fields and enhancing overall safety.

There are often notes and articles in the media about numerous fires, fires, and, as a result, deaths and injuries (especially among children), caused by violations of fire safety regulations when handling pyrotechnic products. The risks of injury and death of people during the handling of pyrotechnic products very high, many issues related to ensuring fire and explosion safety during transportation, storage, and use of pyrotechnic products have not been resolved. The article discusses the existing methods for assessing the fire and explosive properties of pyrotechnic products. During the verification experiment, it was found that the existing approaches do not allow for a correct assessment of the safe zone by the impact of a shock wave for low-power pyrotechnic devices (up to 0,05 kg in TNT equivalent). It is proposed, based on the experimental data obtained, to introduce a correction factor for low-power charges.

The numerical approach to investigate the protective shell behavior under shock wave from an explosive device was presented. Comparison of shock wave characteristics from different explosive devices that were obtained experimentally and by Sadovsky’s analytic formulas was made. The hemispheric geometrical model of shock wave and two finite element models of the cylindrical steel protective shell with the surface areas that had certain values of overpressure and positive impulse were created using NASTRAN software. As an example, the positive phase of shock wave from an explosive device with a TNT equivalent of explosive mass 250 kg was considered. Overpressure was given as the evenly distributed load which depended on the distance from explosion epicenter to the shell surface areas. Shell behavior from the static action of overpressure was investigated in the nonlinear formulation by the Newton-Raphson method and compared with the results of the linear static and buckling analysis. The critical load coefficients and static characteristic of shell were obtained. The first step of the dynamic investigation was modal analysis of shell using the Lanczos method. The positive impulse was presented in the shape of a triangle with a certain time of action. The largest period of shell natural oscillations was taken account. Influence of positive impulse of shock wave on the dynamic behavior of the two shell models was investigated by the fourth-order Runge-Kutta method. The shell state at the different time of positive impulse was presented. The results of static and dynamic analysis allowed to assess the impact of shock wave action from the explosive device on the stressed deformed state of the protective shell.

The present work conducts an experimental and numerical analysis of crater formation resulting from contact surface explosions in soil, utilizing the Coupled Eulerian and Lagrangian (CEL) approach. The crater formation caused by the detonation of an explosive in soil, including shock and elastic-plastic wave propagation in soil, has been numerically simulated using the CEL method. An explosive equivalent to TNT was detonated in direct contact with the soil to examine crater shape, specifically diameter and depth. The numerical model was constructed to correspond with experimental conditions, and findings were compared. The JWL state equations were employed to delineate the properties of the explosive material. The mechanical characteristics of the explosive and soil materials were delineated utilizing the Mohr-Coulomb model, and the deformations acquired via the CEL approach were compared with experimental data. The ejecta generated in the soil due to the explosion, the dimensions of the crater, and the propagation of the shock wave significantly influence soil behavior. This study offers critical insights into soil behavior relevant to defense sector applications and incidents involving explosions, whether accidental or terrorist in cause.

No abstract available

To prevent structural damage in a contact explosion, the blast load must be discharged without damaging the structure. Contact blast tests were conducted in our study using TNT-equivalent explosives of between 125 g and 350 g, and prefabricated hollow-core plates were utilized to evacuate the blast load. Two types of hollow sandwich plates (HSPs) were designed with reference to this experiment. Then, contact and close-contact explosions were carried out on HSP samples using between 350 g and 1100 g of TNT-equivalent explosives. Comparisons were conducted using pressure/time charts from the blast tests and numerical analyses of the smoothed particle hydrodynamics (SPH) model. As a result of the experiments, the limit blast load that the sandwich slab structure can carry while maintaining its stability during a contact blast was determined, and it was found that drainage took place on the slab at a level of 10% of the limit explosion pressure load it could carry. This mitigated the explosive energy of the hollow structure by draining it from the voids without compromising the integrity of the structure.

Recent accidental explosions have underscored the urgent need to evaluate the blast resistance of underground structures, particularly shield tunnels. This study investigates the dynamic response and damage evolution of shield tunnels subjected to internal explosive loading to provide critical insights for blast-resistant design and reinforcement. A combined approach of field explosion tests and numerical simulations was used to analyze the effects of explosive equivalent (TNT equivalent) and initiation position (central vs eccentric). The results show that increasing the explosive equivalent significantly amplifies the dynamic response of the tunnel. Eccentric initiation leads to localized strain exceeding the material’s critical threshold on the near-blast side, resulting in perforation and localized damage. In contrast, central initiation causes relatively lower overall damage, with the arch bottom and lower arch shoulder remaining vulnerable areas. This study clarifies the critical influence of explosive load and initiation position on the blast resistance of shield tunnels, providing valuable experimental data and theoretical support for anti-explosion design.

With the frequent occurrence of ship explosion accidents at sea, the safety of ships and crews has attracted much attention. At present, the research on crew injury is relatively weak. Consequently, the current study constructs a numerical model of the ship structure-crew-blast flow field to investigate the discrepancies in injury response of crew members across different sitting postures. LS-DYNA software is used for simulation and direct analysis to evaluate the damage of crew members in different positions under 100 kg TNT equivalent and 2 m blast distance conditions, and the relationship between different explosive equivalents and crew damage is analyzed. The results demonstrate that for crew members situated in working compartment, the injuries incurred across different sitting postures also differed. The lower leg and foot sections were at greater injury risks, while the head area was associated with minimal damage risks. Altering upper body postures of the crew human body had only a very small impact on lower extremity injuries. Moreover, positive correlations were exhibited between explosive equivalents and crew injury values. The research findings may offer references for injury analysis and protective device design of naval personnel.

In the process of developing energetic materials, it is necessary to evaluate the explosive power of energetic materials, especially the destructive effect of shock waves. Overpressure measurement is an important method to evaluate the power of shock waves. This article proposes an overpressure sensor based on BiScO3–PbTiO3 (BSPT) piezoelectric ceramic nanofibers (NFs). The BSPT NF sensor has the characteristics of high-temperature and high-pressure impact resistance and can be used for shock wave measurement. Experimental results show that the BSPT NF sensor has high-temperature stability; the sensitivity remains above 5.4 V/N at 60 °C–220 °C, and its sensitivity is still higher than 3.7 V/N at 240 °C. In addition, the BSPT NFs overpressure sensor has excellent overload resistance, measuring up to 65 kPa of overpressure without any damage when the trinitrotoluene (TNT) equivalent is 9.6 kg and the sensor is 4 m away from the explosion center. The results indicate that the BSPT NFs overpressure sensor has great application potential in the field of explosion testing.

The aircraft gun firing will cause serious impact on airframe structure. According to the gun firing principle, the muzzle blast wave is simulated by chemical explosion. ALE method is used to deal with the fluid-structure interaction between high-pressure flowing air and the surface of the cabin. Then the expression model of the impact load is established. The numerical calculation is completed to analyse the dynamic response of the cabin structure under the impact load. The parameters of load and cabin model are modified by using the experiment results. Comparing the calculated dynamic response with the experiment results, the error is within acceptable range. Multiaxial stress equivalence and rain-flow counting method are used to process the simulation impact response data to estimate the impact fatigue life. In conclusion, the paper provides a feasible method for analysing dynamic response and fatigue life of gun cabin structure.

Abstract In order to ascertain how explosive load influences orthotropic slabs with short span stiffeners partially positioned in the x-direction, the purpose of this study is to perform a numerical analysis. The maximum displacement of a floor surface with respect to the force of an explosive load and the angle of inclination. It is feasible to calculate the impact of the angle of inclination and the height of the blast load on the vertical deflection of the slab using the 6th order polynomial blast equation, as long as the local blast load is positioned in the center of the slab. An analysis reveals that the vertical deflection of the slab is affected by the timing of the explosion. Specifically, a more powerful explosion has a diminishing effect on the deflection of the slab. The inclination angle has no major impact on the outcomes of deflection.

No abstract available

The dynamic load in the soil directly leads to the damage of underground structures upon explosions. In this study, a method to predict blast load on underground structure surface based on the neural network was developed to study the load distribution under close-in detonation. First, taking the underground utility tunnel as the experimental structure, 52 groups of field blast tests were conducted on the surface load mechanism, and the surface load data samples were obtained. Second, the key influencing parameters of the reflected blast load were obtained through the dimensional analysis method, and the backpropagation neural network model was constructed based on the test data using the Levenberg–Marquardt algorithm to train and optimize the neural network. Finally, the accuracy of load prediction results was compared and evaluated among the neural network, empirical formula, and nonlinear regression analysis (NRA) methods. It is found that the input parameters of combined variables can further improve the prediction accuracy of the neural network compared with the input parameters of single physical variables. Compared with the empirical formula method and the NRA method, the neural network model with input parameters of combined variables provided the most accurate prediction. The load distribution under typical conditions calculated by the neural network showed that the explosive setting parameters impact the uneven shape of blast load on the structure surface. The increase in explosive equivalent and depth reduces the nonuniformity of load distribution, while the decrease in explosion distance increases the nonuniformity of load distribution.

The service environment of civil air defense engineering structures is relatively harsh, and the corrosion of steel bars is the main reason for reducing the durability of concrete structures in civil air defense engineering. A hybrid FRP–steel-reinforced concrete (hybrid-RC) structure has excellent durability. Therefore, it is a good choice to apply hybrid-RC to civil air defense engineering structures. In order to study the blast resistance of hybrid-RC structures, close blast and contact blast experiments were carried out on hybrid-RC slabs, steel-reinforced concrete (SRC) slabs and GFRP-reinforced concrete (GRC) slabs. For the close blast experiment, the steel reinforcement in the SRC slab first entered the plasticity stage, whereas the GFRP reinforcement in the hybrid-RC slab was in the elastic stage under the close blast. Therefore, the capacity to dissipate energy through the vibration in the hybrid-RC slab was better than that of the SRC slab. The residual deformation in the hybrid-RC slab after the close blast experiment was smaller than that of the SRC slab. The Blast Recovery Index (BRI) was introduced to evaluate the recovery capacity of the concrete slab after the close blast, and damage assessment criteria for the hybrid-RC slabs were proposed according to the maximum support rotation θm and BRI. There was little difference in the size of the local damage in the hybrid-RC slab and the SRC slab under the contact blast. However, since the GFRP reinforcement was still in the elastic stage and the steel reinforcement was plastic after the contact blast, the ratio of the residual bearing capacity to the original bearing capacity in the hybrid-RC concrete slab would be larger than that of the SRC slab. The prediction formula for the top face diameter D and blasting depth L of the hybrid-RC slab was obtained through dimensionless analysis. This research can provide a reference for the anti-blast design of hybrid-RC slabs.

No abstract available

The failure of column, which is a critical compressive structural member of a building, may lead to devastating progressive collapses. The present numerical study involves investigation on the performance of as-built and strengthened RC columns using 0°/90° CFRP layers under blast loading. A nonlinear FEA program, LS-DYNA was employed to study the RC columns response when subjected to blast loading. Blast field test data from recent literatures was employed for validation and further parametric studies. Variables considered were different charge masses, height of bursts, concrete compressive strengths, standoff distances, tie spacings, transverse reinforcement steel detail schemes, and 0°/90° CFRP layers. It was revealed that scaled distance parameters had a significant effect on the behaviour of RC columns under blast loading. Compared to as-built column, 0°/90° CFRP strengthened RC columns displayed excellent blast resistance. Transverse reinforcement steel details had a significant effect on lateral displacement response and failure modes of RC columns. Compared to conventionally-detailed columns, seismically-detailed columns and transverse reinforcement steel bars accompanied with square-diamond shaped ties exhibited enormous blast resistance capacity.

To explore the distribution of cracks in anchored caverns under the blast load, cohesive elements with zero thickness were employed to simulate crack propagation through numerical analysis based on a similar model test. Furthermore, the crack propagation process in anchored caverns under top explosion was analyzed. The crack propagation modes and distributions in anchored caverns with different dip angles fractures in the vault were thoroughly discussed. With the propagation of the explosive stress waves, cracks successively occur at the arch foot, the floor of the anchored caverns, and the boundary of the anchored zone of the vault. Tensile cracks are preliminarily found in rocks that surround the caverns. In the scenario of a pre-fabricated fracture in the upper part of the vault, the number of cracks at the boundary of the anchored zone of the vault first decreases then increases with the increasing dip angle of the pre-fabricated fracture. When the dip angle of the pre-fabricated fracture is 45°, the fewest cracks occur at the boundary of the anchored zone. The wing cracks deflected to the vault are formed at the tip of the pre-fabricated fracture, around which are synchronous formed tensile and shear cracks. Under top explosion, the peak displacement and the peak particle velocity in surrounding rocks of anchored caverns both reach their maximum values at the vault, successively followed by the sidewall and the floor. In addition, with the different dip angles of the pre-fabricated fracture, asymmetry could be found between the peak displacement and the peak particle velocity. The vault displacement of anchored caverns is mainly attributed to tensile cracks at the boundary of the anchored zone, which are generated due to the tensile waves reflected from the free face of the vault. When a fracture occurs in the vault, the peak displacement of the vault gradually decreases while the residual displacement increases.

With an unprecedented rise in explosions occurring in urban regions, it has become imperative to revisit the classical reflected blast wave problem, characterizing its backwards propagation into disturbed medium after impinging on surfaces, such as buildings. When encountering obstacles in its path, blast waves reflect backwards and become defined by more intricate decay characteristics than its unobstructed counterpart and can only be obtained via complex numerical simulation. Attempts to produce an analytical solution to post-reflection blast waves have been limited in scope and unapplicable to broader ranges of explosion scenarios. Here, we introduce a numerical data-driven, closed-form solution, R(t,θ,Z), to map the three-dimensional trajectory and decay behavior of reflected blast waves. We demonstrate the solution's accuracy within, and beyond, scaled blast strengths of 0.5≤Z≤4.0 m/kg1/3 and its adaption to arbitrary explosion sizes through Cranz–Hopkinson blast scaling law. In addition, a closed-form solution on directional post-reflected overpressure is formulated. We discuss how the developed models advance fields of blast wave collision theory, urban blast pattern formation, and real-time identification of repeated blast exposure to personnel in urban blast events. Our work provides a foundation for understanding asymmetric collisions of blast wave and pioneers a generalized fast-running solution for post-reflection explosions, enhancing military operational safety and first aid in blast trauma scenarios previously unachievable.

No abstract available

In this paper, we chart a path to a method that enables us to extract temporal and spatially varying pressure loading effects on the transient response of steel plates under near‐field blast loading, employing ultra‐high‐speed cameras and DIC to measure the transient deformation field. The study addresses the challenges of obtaining full‐field, high‐fidelity DIC measurements in extreme blast environments by conducting small‐scale detonations in close proximity to steel target plates using two ultra‐high‐speed camera systems. A comprehensive error analysis of these systems is reported and challenges the historic norms of reported accuracy and repeatability in such testing, showing that errors as low as 0.01 mm can be achieved in transient measurements. Pressure measurements obtained via non‐contact DIC are compared with data from Hopkinson pressure bar measurements, providing cross‐validation of the methods. This research highlights the critical influence of several factors on the reliability of the results, including the chosen camera system, the geometry of the target plate and the errors introduced during DIC processing. The study demonstrates that, with careful attention to experimental design, short exposure times, thorough error evaluation for each camera system and consideration of the structural response, blast test results from DIC can be independent of the camera system used. Furthermore, the study finds that the design of the plate for obtaining accurate impulse distributions is more critical than the inherent camera system uncertainties. Within these limitations, the spatial distribution and temporal development of the impulse loading inferred from the DIC velocity data shows excellent correlation with direct measurements of impulse applied to a nominally rigid target by an identical explosive detonation. This offers a path to a method that could achieve the hitherto impossible task of extracting accurate data on the blast load applied in the extreme nearfield to deforming targets.

Under dynamic impact and blasting pressures, this investigation concentrates on the mechanical properties and failure mechanisms of soft coal-rock masses. The study follows a problem-methodology-results-application structure to systematically address these engineering challenges. In Huainan, China, we employed a custom experimental apparatus and a Separate Hopkinson Pressure Bar (SHPB) to conduct dynamic experiments on materials from the C13-1 soft coal seam, as well as its roof and floor, for blasting simulations. According to the findings, the dynamic compressive strength of coal, floor strata, and roof strata increases as the impact pressure increases. More specifically, the maximal strengths of these materials were 23.3 MPa, 16.9 MPa, and 6.57 MPa, respectively. These values are 3.3, 2.9, and 3.9 times their static compressive strengths. Superimposed damage zones and an increased risk of gas outbursts are the result of stress waves propagating and reflecting within coal fissures, as indicated by blasting simulations. It is imperative to implement effective safety strategies, including structural reinforcement and controlled pyrotechnic use, in order to mitigate these risks. The results enhance our understanding of the multi-scale mechanical behavior of coal-rock systems and provide valuable insights for the advancement of safer mining practices.

This paper demonstrates the application of the Johnson–Holmquist II (JH-2) model with correlated and validated parameters to simulate the behavior of a sandstone. The JH-2 model is used to simulate various tests, including single-element tests, structural quasi-static uniaxial and triaxial compression tests, and the split Hopkinson pressure bar test. Additionally, the model is used to simulate drop-weight impact test using a ball bearing and two loading scenarios involving small-scale blasting and projectile impacts. Quantitative and qualitative comparisons demonstrate that the JH-2 model agrees well with both experimental and analytical results. Limitations of the model are also highlighted, particularly for quasi-static problems, as the model was originally developed for high-strain-rate simulations. Ultimately, this study demonstrates that the JH-2 rock constitutive model can obtain reasonable results for a material other than the material for which the model was originally correlated and validated. This paper provides valuable guidance for modeling and simulating sandstone and other rock materials subjected to dynamic loadings.

The seismo-acoustic analysis approach, which is based on the fusion of acoustic and seismic data, is an extremely effective way of monitoring the yield of explosions over a long distance. To address the problem of estimating the explosion yield at a multi-ground-medium-mixed site (abbreviated as mixed site), this article derives the general explosion yield prediction forms of acoustic model and seismic model, establishes the inversion method for explosion source parameters at mixed site by introducing the ground medium amplification factor, analyzes the inversion accuracy by using experimental data, and discusses the amplification effect and the influence of different scaling relationships. The experimental results indicate that the dispersion of the acoustic impulse relative to the overpressure decreases with distance and the linear relationship of acoustic impulse is better on a logarithmic scale, whereas the vertical component of the first peak of the seismic particle velocity and displacement, as well as the radial-vertical-tangent vector sum, exhibit a good linear variation law over a certain range on the logarithmic scale. The results of the source parameter inversion demonstrate that when the amplification factor is introduced, the inversion of the explosion source parameters of the mixed site has a high accuracy for yield estimation; however, when only single hard-rock media is considered, the inversion of the explosion source parameters produces large errors. The results of the amplification effect and scaling relationship analysis indicate that geological amplification has a substantial effect on the explosion source parameter inversion results, and that the data dispersion degrees of Sachs and KG85 scaling relationships are essentially identical.

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Abstract Computational fluid dynamics (CFD) technology was employed to investigate the detonation characteristics of a green high-energy metal–organic framework (HE-MOF) material. Experimental work on this relatively new class of materials is limited. Therefore, high-fidelity large-eddy Simulation (LES) is performed to investigate the impact of the explosive on the shockwave propagation and the latter interaction with obstacles. First, we validate the numerical framework against the laboratory measurements carried out for trinitrotoluene (TNT). Among the HE-MOF materials, [Cu(Htztr)2(H2O)2]n is selected due to its appropriate explosive specifications owing to its special chemical structure. The real gas equation of state of Beker–Kistiakowsky–Wilson (BKW) is employed to account for large density change of air during the explosion. For LES, an extended solver is developed within the open-source OpenFOAM package. Supersonic flow visualization clearly shows positive reflected and incident pressure. Comparisons between the TNT and HE-MOF demonstrate higher blast wave intensity and larger affected area for HE-MOF at identical times. The results of the current study suggest that the HE-MOF produces an impulse 2.5 and 2.28 times greater than TNT in the non-obstructed and obstructed sides of the explosion, respectively.

The design and planning of structural components, such as columns, to resist blast loads is a complex task. Often standard free-field blast loads, specified in design codes or other literature, are used for the analysis of the object. These loads are then further increased or decreased depending on the topology of the surrounding geometry (Mach-Stem), the shape of the impacted object itself, and blast wave reflection. However, most of these research works focus purely on the assessment of the structural components itself, ignoring a complex fluid mechanics phenomenon such as diffraction, which is of particular interest when circular columns are standing next to each other or placed in front of a façade. The article addresses three main topics. First, the article answers the question whether the area behind the column is protected, meaning constituting a shadowed area. We present findings that the close area behind a column is subjected to higher pressure and impulse values as there would be without the column. Hence, the incident pressure sees significant pressure buildup due to diffraction. This pressure buildup is quantified using pressure increase factors and presented together with the accompanying impulse. Second, this pressure buildup is of relevance for realistic design of a façade behind the column, which is not covered in current design codes at all. We discuss relevant parameters in the design process. Third, directly coupled with the assessment of the pressure buildup behind the column due to diffraction is the assessment of pressure and impulse in the area behind the column due to multi-wave reflection at a façade, leading to a significant pressure and impulse scale-up, which might be relevant for design of a column and/or a façade. This article identifies gaps in understanding diffraction and subsequent multi-reflection of blast wave within a structural design framework and provides insights on how to establish safe design accounting for these effects.

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Hydrogen energy is pivotal in the energy transition due to its high efficiency and zero-emission characteristics. However, the potential for explosions constrains its broader application. Gaining insights into the dynamics of overpressure in hydrogen explosions is vital for the safe design of explosion-proof facilities and the determination of equipment spacing. This study investigates hydrogen explosions in open spaces of 1 m³ and 27 m³ volumes, analyzing flame propagation and overpressure distribution. It also evaluates the accuracy of three theoretical models in predicting peak overpressure. The results reveal that the spherical flame from a hydrogen cloud explosion transforms into an ellipsoidal shape upon contact with the ground. The average flame propagation velocity across different equivalent ratio is ordered as follows: Va (φ = 1.0) > Va (φ = 1.5) > Va (φ = 2.5) > Va (φ = 0.5). At equivalent distances, the peak overpressure of hydrogen cloud explosions is comparable across both scales. The traditional trinitrotoluene model overestimates the peak overpressure of hydrogen cloud explosions at both scales. The optimized trinitrotoluene model achieves over 90% accuracy in predicting hydrogen cloud explosions in 1m³ volumes but shows decreased accuracy in 27 m³ explosions. At source intensity level 3, the Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek multi-energy model exhibits a prediction accuracy of over 70% for peak overpressure in hydrogen cloud explosions, with consistent performance across different scales, rendering it a more reliable model for such predictions. This research enhances hydrogen safety assessment technologies by providing a more precise method for evaluating large-scale hydrogen cloud explosion risks.

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In view of the flammable and explosive characteristics of oil and gas pipeline transportation medium, once it leaks, production safety accidents are easy to occur. This study uses explosions with severe consequences caused by natural gas pipeline leakage as an example. The risk factors and accident modes of oil and gas storage and transportation pipelines are analyzed; the explosion load is calculated by a scaling explosion prediction model with the TNO multi-energy method; the relationship between overpressure load and combustible gas cloud radius is studied. The methane-air explosion volume fraction of 9.5% is taken as another example, with which the overpressure attenuation law of explosion wave is obtained. Based on the above research, safety risk prevention and control measures are proposed. The research results can provide technical support for daily management and risk prevention and control of oil and gas storage and transportation pipelines.

Understanding the dynamic characteristics of deep-sea explosions is essential to improve the survivability and combat capability of deep-sea equipment. In this paper, by considering the practical underwater conditions, we investigated the mechanical effects of the deep-sea 1-kg-trinitrotoluene (TNT) explosion with charge depths ranging from 1 to 10 km through numerical simulation and dimensional analysis. The shock wave overpressure, the positive overpressure pulse, the bubble pulse, and the energy distribution for various depth explosions were analyzed systematically. The simulation results showed that the charge depth was negligible for the peak overpressure of the shock wave. However, the positive overpressure pulse, the shock wave energy, the maximum bubble radius, the bubble energy, and the bubble period decrease significantly with increasing the charge depth. Then, the dimensional analysis for deep-sea TNT explosion was performed to reveal the key dimensionless parameters, from which the scaling laws of the shock wave overpressure and the overpressure pulse were obtained. By fitting the simulation results, the dimensionless equations were proposed, providing an effective method for predicting the peak overpressure and the positive overpressure pulse of shock wave for underwater TNT explosion over a wide range of water depths.

Landslide-generated impulse waves (LGIWs) usually have a severe impact on the normal operation of the reservoir area. This study conducts probabilistic analysis of LGIWs generated by Rongsong (RS) deposit by combining the energy equivalent method, large-scale physical similarity model experiment and machine learning surrogate model. The energy equivalent method utilizes a wave generation model to get the initial waveform and employs a wave propagation model to evaluate the LGIWs in the study area. The two models are connected by the initial wave, ensuring that the total energy and the energy release rate transferred from the landslide to the water body remain consistent with the simplified landslide. This method is used to study the LGIWs hazard chains induced by RS deposit, and a large-scale physical similarity model experiment is carried out to verify. Subsequently, taking into account the uncertainties of landslide velocity and the volume of unstable mass, a surrogate model is established to get the probability distribution of the impulse waves runup height on the dam. The results show that the energy equivalent method is able to accurately simulate LGIWs hazards. The runup height on the Rumei (RM) dam is concentrated between 11.02 and 12.62 m, accounting for 0.76. It is recommended to install a 1.2 m wave wall on the dam crest. This study provides a novel method for conducting probabilistic analysis of LGIWs in mountain reservoirs, and offers valuable references for disaster prevention and control in the reservoir area.

To calculate sound pressure level of near-field and far-field explosion impulse noise, the simulation model of near-field and far-field explosion impulse noise with joint simulation method of finite element and self-programming. Near-field explosion model is established with finite element method and fluid structure interaction method. Calculation model of far-field impulse noise is established with attenuation formula of sound pressure level, conversion formula of shock wave overpressure and impulse noise, and self-programming method. Sound pressure level of impulse noise can be calculated automatically at any distance from the explosion center. The results show that the simulation results of near-field and far-field impulse noise are in good agreement with static explosion test, and the error is less than 14%. The joint simulation method of finite element and self-programming can also provide a feasible method for the near-field and far-field power calculation, effectiveness evaluation and safety analysis of various explosive ammunition.

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The aim of the present paper was to report on an experimental study of the characterization of a blast wave initiated by a solid explosive and its interaction with a rigid obstacle in the form of a hemicylinder. Pressure transducers located along the path of the blast wave and high-speed imaging allow (1) the measurement of the overpressure at different locations and (2) the characterization of the blast wave inception, propagation, and reflection off the hemicylinder. The scaling effect has been investigated by performing experiments in two different facilities, where one is at twice the scale of the other.

Explosive phenomena pose significant threats to structural integrity, necessitating accurate prediction models for designing resilient infrastructure. Traditional computational approaches like CFD and FEM, while detailed, require substantial computational resources and specialized expertise. This study presents an alternative approach using the Discrete Element Method (DEM) implemented through the Pymunk physics engine for 2D explosion modeling. The developed method models explosions as radially distributed particles with initial impulses, simulating shock wave propagation through particle collisions. Structures are represented using a modular approach, enabling detailed analysis of impulse distribution across different building elements. The simulation tracks collision events and calculates impulse transfer using momentum conservation principles. Model validation was performed against UFC 3–340–02 standards by investigating three scaling methods: proportional coefficient, linear regression, and a non-linear power–law model. The power–law model demonstrated the best agreement with reference data, confirming the model's accuracy with a total integral error of only 1.5%. This computationally efficient approach provides a practical tool for structural engineers and urban planners to incorporate blast resistance considerations without requiring high–performance computing resources. The method successfully balances computational efficiency with physical fidelity, making explosion modeling more accessible for rapid assessment scenarios and preliminary design stages.

Large-caliber and long-barrel weapons are important experimental devices for exploring the impact resistance and reliability of warheads. The force of impact of the muzzle jet has a significant influence on the overload resistance of the warhead and surrounding devices. The mechanism of motion of the body inside the tube cannot be ignored owing to the high kinetic energy at the muzzle. In this study, we designed the relevant experiment and a simulation model to analyze the structural characteristics and mechanism of evolution of the shock wave and the vortex structure in a muzzle jet. The aim was to examine the evolution of the shock wave with initial jet-induced interference. And we established three other simulation models to compare the similarities and differences between the results of the models. The results showed that, in the original complex model, the initial jet restricted the free expansion of the muzzle jet, and this led to many shock–shock collisions that retarded the development of the shock waves. Multiple reflected shock waves were thus formed under a high local pressure that distorted the shock structure, while the structure of the shock wave in the simplified models was clear and simple. The parameters of motion of the body changed by a little when the initial jet-induced interference was ignored. The difference in values of the strongest impact force measured at monitoring points far from the muzzle was small, with an error of about 2%, such that the simplified model without the initial jet could be used in place of the original complex model. The other simplified models yielded significant differences. Our results provide an important theoretical basis for further research on the muzzle jet and its applications in engineering.

Explosively driven shock wave radius versus time profiles are frequently used to document energy release and relative explosive performance. Recently, two universal shock wave radius versus time profiles have been presented in the literature, which demonstrate the ability to represent explosively driven shock wave profiles for all explosive sources in any fluid environment. These two universal shock wave profiles are examined here relative to each other and relative to a commonly used nonlinear shock wave profile, which is fit to experimental data for individual explosive materials. The nonlinear profile, originally developed by Dewey, is examined here, and a universal non-dimensional form of the equation is proposed. The universal shock wave profiles are all found to be relatively similar, but with slight variations in a transition region of non-dimensional radii 0.15≲R∗≲2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$0.15\lesssim R^*\lesssim 2$$\end{document}. The variations in this region result in different estimations of energy release or blast strength between the curve fits.

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Nowadays, the safety of infrastructure and people is a primary concern. To ensure safety in public, industrial, or military facilities, it is necessary to be able to predict the behavior of shock waves in any environment. However, while the physical phenomena that occur in free field are well known, they cannot be applied to follow the path of a shock wave in a closed medium, where the phenomena are more complex. The aim of the present study was to define the origins of the different reflections and the path followed by the shock waves after the first reflection in a closed environment composed of two chambers separated by a wall with a variable opening. To achieve this, a fast code was developed based on the shortest path algorithm to determine the parameters of the shock wave at any point of a simple geometry. The code was designed from small-scale experiments that enabled the predictive laws of the distribution of maximum overpressure, total impulse, and the arrival times of the first four peaks to be established. An application of the code is presented in the last part of the paper.

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The interaction between a shock wave and an object causes an impulsive force on the object that lasts for a very short time on the order of milliseconds. This study proposes impulsive force measurements using anodized aluminum pressure-sensitive paint (AA-PSP), which is an optical pressure measurement technique. The response time of AA-PSP is on the order of microseconds, indicating the potential for fast pressure drag measurements by integrating the pressure distribution on the surface. In this study, at first, the response time of the fabricated AA-PSP is measured and determined to be 3.3μs\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$3.3~\upmu \hbox {s}$$\end{document}. A cylindrical model coated with the AA-PSP is installed at the outlet of a shock tube, and the surface pressure is measured in order to calculate the pressure drag with a time resolution of 10μs\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$10~\upmu \hbox {s}$$\end{document}. The experimental results are compared with an Euler CFD simulation computed using an in-house code. The maximum pressure drag in the numerical result exceeds that in the experimental result; however, the maximum pressure drag timings are in good quantitative agreement. In addition to measuring the impulsive force, the AA-PSP results allow for the visualization of complex flow phenomena, such as diffraction and decay in the shock wave strength. This simultaneous measurement of the flow field and impulsive forces can deepen the understanding of the relationship between them.

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This paper presents a numerical study on the laser shock wave propagation in a 3D woven carbon-fiber-reinforced polymer (CFRP) material by means of detailed and homogenized finite element (FE) models. The aim of this study is to numerically characterize the shock wave response of the 3D woven CFRP in terms of back-face velocity profiles and the induced damage, and to investigate whether the detailed FE models could be effectively replaced by homogenized FE models. The 3D woven geometry was designed using the TexGen 3.13.1 software, while the numerical analyses were executed using the R11.0.0 LS-Dyna explicit FE software. A high-strain-rate behavior was considered for the matrix. The fiber bundles in the detailed models were modeled as a high-fiber-content unidirectional composite laminate, with its mechanical properties calculated by micromechanical equations. A progressive damage material model was applied to both the fiber bundles of the detailed model and the homogenized models. The results of the detailed model reveal a considerable effect of the material’s architecture on the shock wave propagation and sensitivity of the back-face velocity profile to the spot location. Consequently, the homogenized model is not capable of accurately simulating the shock wave response of the 3D woven composite. Moreover, the detailed model predicts matrix cracking in the resin-rich areas and in the bundles with high accuracy, as well as fiber failure. On the contrary, the homogenized model predicts matrix cracking in the same areas and no fiber failure.

Low permeability is a key geological factor constraining the development of shale gas, and reservoir modification to improve its permeability is a prerequisite. Controlled shock wave fracturing can induce the formation of complex fractures in reservoirs and is expected to become an important means of reservoir modification. However, the mechanism of controlled shock wave fracturing in shale and the geological engineering control factors are unclear. Therefore, this article reveals the mechanism and effect of shock wave modification through small-scale experiments and large-scale numerical simulations. Results show that as the impact number increases, a significant increase in large fractures and fracture connectivity within the shale samples is observed, while the correlation between the geometric parameters of the fractures and the number of impacts is weak. High-energy input in the model will cause a larger range of damage to the rock, accompanied by a smaller attenuation index, indicating that the speed of energy attenuation plays a decisive role in rock damage. The influence of crustal stress is greater than the speed of energy attenuation, and higher crustal stress will inhibit the formation of fractures. A moderate increase in the number of controllable shock waves is beneficial for the fracturing effect; however, further increasing the loading number of controllable shock waves will weaken the strengthening effect of the fracturing effect.

The underwater electrical wire explosion (UEWE) is a physical phenomenon initiated by the rapid injection of electrical energy, triggering an explosive event. UEWE offers advantages in energy conversion efficiency, repeatability, and controllability, making it valuable in various industrial applications. Building upon established zero-dimensional (0D) and one-dimensional (1D) models, this paper proposes an enhanced 0D-1D coupled cold-start model to describe the plasma channel expansion and subsequent shock wave (SW) propagation characteristics. The model comprises two submodules: a 0D magnetohydrodynamics model that describes plasma channel boundary expansion during the explosion, and a 1D hydrodynamics model using an artificial viscosity algorithm to depict SW propagation. The constructed numerical model facilitates investigation of plasma characteristics, SW propagation behavior, and energy conversion efficiency throughout the UEWE process. Additionally, the influences of wire dimensions and discharge frequency on these characteristics were analyzed. The results indicate that SW propagation characteristics are primarily governed by thermal pressure variations within the wire and that different wire dimensions markedly affect SW amplitude, attenuation, and impulse. The efficiency of electrical-to-SW energy conversion remains relatively low; however, thicker and shorter wires can enhance SW amplitude and improve conversion efficiency. Higher discharge frequencies produce greater impact forces and impulses near the explosion site, while also improving energy conversion rates. This study offers a theoretical basis and technical guidance for prospective engineering applications.

Carbamide Peroxide, an adduct of Urea and Hydrogen Peroxide (UHP) industrially used as a solid source of hydrogen peroxide, exhibits the behaviour of a tertiary explosive but a detailed performance characterisation is still lacking in the literature. In this work, we calculated a 20 % experimental TNT equivalence for brisance, i. e. the shattering effect from the shock wave transmitted from the detonating high explosive into adjacent materials, by experimental indirect measurement of UHP detonation pressure. We determined a 3.5 GPa detonation pressure for 5 kg unconfined UHP charges (0.87 g/cm3, 120 mm charge diameter) by measuring the attenuated shock wave velocity (ASV) in adjacent inert materials using passive optical probes. Particle velocity measurements at the interface of a PMMA impedance window carried out with Photonic Doppler Velocimetry on scaled‐down charges of 90 g UHP under heavy confinement (0.85 g/cm3, 30 mm charge diameter, 4 mm thick steel) are consistent with ASV results in the PMMA acceptors but further investigations are required to determine the detonation pressure, using a small‐scale experimental setup. The ASV method has proven reliable to assess the brisance of a non‐ideal explosive for risk assessment purposes.

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Structural research teams face significant challenges when conducting studies with explosives, including the costs and inherent risks associated with field detonation tests. This study presents a replicable method for loading spherical and bare TNT-based cast explosive charges, offering reduced costs and minimal risks. Over eighty TNT and Composition B charges (comprising 60% RDX, 39% TNT, and 1% wax) were prepared using spherical molds made of thin aluminum, which are low-cost, off-the-shelf solutions. The charges were bare, meaning they lacked any casing, as the molds were designed to be easily removed after casting. The resulting charges were safer due to their smaller dimensions and the absence of hazardous metallic debris. Composition B charges demonstrated promising results, with their performance characterized through blast and thermochemical experiments. Comprehensive data are provided for Composition B charges, including TNT equivalence, pressures, velocity of detonation, DSC/TGA curves at four different heating rates, activation energy, peak decomposition temperatures, X-ray analysis, and statistics on masses and densities. A comparison between detonation and deflagration processes, captured in high-speed footage, is also presented. This explosive characterization is crucial for structural teams to precisely understand the blast loads produced, ensuring a clear and accurate knowledge of the forces acting on structures.

The dynamic response of polymethyl methacrylate (PMMA) is well understood for one-dimensional planar impact shocks, but limited research has been performed on the response of PMMA under spherical shock loading. In this work, the shock decay of an explosively-driven shock wave into PMMA was experimentally measured. PMMA cubes of various geometries were explosively loaded with an RP-80 detonator to produce the explosive shock wave. High-speed schlieren imaging was implemented to measure the explosively-driven shock wave velocity throughout the PMMA cubes. Photon Doppler velocimetry (PDV) was used to measure the particle velocity imparted by the shock wave at the surface of the cubes. The material shock response was studied at distances from 21.91 to 133.3 mm from the explosive source. The particle velocity history measured by PDV was compared to the wave profile visualized in the high-speed images. The shock wave pulse amplitude decreased with increased distance from the source. The conducted experiments extend the PMMA shock Hugoniot relating to the lower shock and particle velocity regime.

Abstract To investigate the influence of boundary effects on the damage and fracture characteristics of brittle materials under explosive loads, studies were conducted using explosive model experiments and simulation methods. The results indicate that the damage outcomes of single and double boundary models are significantly affected by the variation in the distance (Δl) between the explosion source and the boundary. When Δl is the same, more fragments are generated by the double boundaries. The circumferential tensile stress, produced by the superposition of incident and reflected stress waves at the boundary, is the primary cause for the continuation of crack propagation.

Reduced-scale experiments offer a controlled and safe environment for studying the effects of blasts on structures. Traditionally, these experiments rely on the detonation of solid or gaseous explosive mixtures, with only limited understanding of alternative explosive sources. This paper presents a detailed investigation of the blasts produced by exploding aluminum wires for generating shock waves of controlled energy levels. We meticulously design our experiments to ensure a precise quantification of the underlying uncertainties and conduct comprehensive parametric studies. We draw practical relationships of the blast intensity with respect to the stand-off distance and the stored energy levels. The analysis demonstrates self-similarity of blasts with respect to the conventional concept of the scaled distance, a desirable degree of sphericity of the generated shock waves, and high repeatability. Finally, we quantify the equivalence of the reduced-scale blasts from exploding wires with high explosives, including TNT. This experimental setup and the present study demonstrate the high degree of robustness and effectiveness of exploding aluminum wires as a tool for controlled blast generation and reduced-scale structural testing.