全海深耐压结构设计方法

潜水器耐压壳结构为人员和设备提供安全可靠的工作环境，决定潜水器的潜深和容重比等关键性能指标，是潜水器的核心部件。除传统金属合金外，一些具有高强、轻质性能的非金属材料，如纤维增强复合材料、陶瓷、玻璃等也展现出了巨大的应用前景，成为潜水器提高性能的可靠技术途径。在总结潜水器耐压结构选材应用的基础上，分析不同材料在力学性能、耐海洋环境性能等方面的优劣，为耐压壳结构材料的选择提供参考，并针对现阶段存在的问题展望了未来进一步研究的方向。

载人舱球壳作为全海深载人潜水器最关键的部件，在潜水器下潜及上浮过程中需承受交变海水压力，对结构长期安全性来说是一个巨大的考验。为考核全海深载人潜水器载人舱球壳疲劳性能，本文首次对内径800 mm的载人舱钛合金球壳缩比模型开展疲劳试验研究，分析疲劳载荷对球壳形状、焊缝残余应力、关键部位结构应力、缺陷萌生和扩展的影响，为全海深载人潜水器载人舱球壳的疲劳性能和结构安全性评估提供试验依据。

针对耐压球舱的强度分析问题，常规的球舱强度校核以及压力试验仅考虑耐压球舱，没有涉及到球舱边界条件对强度的影响。由于全海深AUV工作于11 000 m的大深度，本文在对开孔耐压玻璃球舱的强度校核时提出采用从耐压球舱的防撞外壳中抽离出假设球壳，作为耐压球舱的边界条件。同时计入开孔处加强结构对耐压舱强度的影响，补强因开孔而削弱结构强度，以此对耐压球舱做强度分析。此外，在以耐压球舱的形式对全海深AUV耐压设备进行压力试验。研究内容对大深度潜水器的耐压球舱的强度校核具有重要意义。结果表明：所设计的耐压球舱完全能承受全海深11 000 m处的压力，满足设计的需求。

有机玻璃 (polymethyl methacrylate, PMMA) 是一种透明高分子化合物，具有透明性好、耐腐蚀、重量轻、机械强度优异等优点，可作为全通透潜水器耐压壳体材料的候选材料。PMMA是一种黏弹性材料，当经受长时间的外界高压作用时，由PMMA制成的耐压结构可能发生蠕变，导致其承载能力下降。本文对PMMA耐压壳体进行了有限元分析，基于温度相关的时间硬化蠕变模型，获得了壳体的蠕变变形，并研究了不同类型无开孔和有开孔的耐压壳体的蠕变特性，分析了不同压力和温度下PMMA耐压壳体的应变-时间曲线和位移曲线。分析结果将为大深度载人潜水器全通透耐压舱的设计提供理论参考。

在圆截面环形耐压壳基础上，提出一种新型波纹截面环形耐压壳。通过耐压壳体极限强度非线性分析方法，研究波纹数对波纹截面环形耐压壳屈曲载荷的影响规律，优选出一种波纹截面环形耐压壳，并与圆环壳进行对比分析。结果表明，随着波纹数的增加，波纹截面环形耐压壳的屈曲载荷大幅度提高，当波纹数增加到12时，波纹截面环形耐压壳承载能力高达圆截面环形耐压壳的98%，但波纹结构的制造难度和成本大幅度降低。本文研究可为深海空间站的创新设计提供参考。

耐压壳是深海潜水器中最关键的结构，直接关系到潜水器安全性和总体性能.本文对当今的单层耐压壳结构设计进行了评述，并设计了一种基于分层/分压的新型耐压壳结构，该结构借鉴了自然界的两种深潜动物的结构：抹香鲸分层结构和鹦鹉螺隔片分割螺壳亚结构.综合了这两种结构特性的双层壳结构能够有效提高抗压能力，从而提升深潜能力.与以往单层球壳的耐压壳结构相比，该结构不仅提高了强度，也提高了抗屈曲能力.同时，该结构还兼具大容积、高可靠性、以及避免超厚壳制备上的难点等特征，使得深海潜水器的综合性能得到显著提高.新结构中的桁架将圆壳分割为若干个柱壳亚结构，本文针对此亚结构严格推导了桁架增强壳体抗屈曲的公式.从实验数据中总结出来的泰勒水池公式是目前广泛使用的潜水器壳体设计依据，新推导的公式与之相比只有6%的差别，这使得新型结构设计有了更坚实的理论基础.

在深海资源开发和发展深海技术的背景下，我国完成了载人潜水器的谱系化建设。近年随着对水下观测需求的增加，全通透载人潜水器引起广泛关注。本文基于有机玻璃试件压缩试验的结果，在LS-DYNA软件中建立有限元模型，通过试件模拟失效模式与试验结果对比，对典型的全透明深海耐压载人潜水器的失效分析进行敏感性研究。在准静态外压下进行极限强度分析之前，进行一阶线性屈曲模态分析以模拟初始几何缺陷。对有机玻璃载人潜水器的耐压壳失效形式和极限载荷进行分析，采用有限元分析方法，研究特定厚度半径比的有机玻璃载人潜水器的临界载荷，为其制造提供技术指导。

深海耐压壳安全研究主要集中在材料性能本构模型和以疲劳寿命预测为目标的结构参数评估模型上，其损伤识别和定量评估方法的研究尚不成熟。本文针对深海耐压结构，基于电磁感应和涡流热效应，探究瞬态温度响应与微裂纹损伤间的关系，以实现耐压壳关键部位微裂纹的量化研究。项目研究成果将弥补耐压壳服役安全性研究中无损伤监测的空白，为深海耐压壳微裂纹损伤识别提供原创方法及理论依据，保障目前在役深海潜水器的作业安全。

耐压结构材料是支撑海洋装备“下得去、上得来”的基础,钛合金以其质量轻、强度高、耐腐蚀的特点而成为深海载人装备耐压结构的优选材料,具有良好应用前景。该文简述了潜艇、深潜器、深海工作站和水下实验室等典型深海载人装备及其耐压结构材料的发展历程和研究进展,介绍了我国的钛工业发展现状、海洋工程用钛合金材料体系、钛合金耐压结构加工制造技术以及设计与试验研究等方面的研究基础,并结合大型深海装备钛合金结构的技术特点分析了耐压结构用钛合金的关键科学技术问题和应用需求,为深海载人装备耐压结构用钛合金的未来发展提供参考。

环肋圆柱壳是深潜器耐压结构的主要形式，但由于极限承载能力和振动特性的需求，存在不同的环肋布局形式。为探究环肋布局对钛合金圆柱耐压壳内爆的影响，基于任意拉格朗日欧拉方法开展数值研究。首先对比试验结果验证液-固-气三相流固耦合数值模型的准确性。然后分析3种环肋布局下圆柱耐压壳水下内爆过程中的结构动态响应、冲击波传播以及能量演化等特征。结果表明，环肋均布时，内爆中心由筒体中部向一端移动。而中部和端部加强时，内爆中心由环肋稀疏位置向密集位置移动，结构动能均存在显著的二次波峰现象。此外，中部加强能有效降低最大冲击波峰值。通过对环肋圆柱壳内爆响应特性的分析，对深海耐压结构的设计具有重要的工程意义。

深海载人潜水器是海洋资源勘探和开发的重要装备，其载人舱球壳是保证下潜人员安全及舱内设备正常工作的基础，为及时掌握载人舱球壳在长期使用过程中的安全状态，对其进行健康监测与实时评估十分必要。本文首先对4 500 m潜水器载人舱球壳进行受力分析；然后根据球壳特征和监测需求 design 载人舱球壳健康监测评估系统；对钛合金蠕变对系统测量结果的影响进行了研究分析，研究结果表明在最大工作压力下蠕变对测量结果的影响小于1%；最后给出了结构安全性评估算法函数，并用球壳静水外压试验数据对结构评估算法进行验证。

潜水器是海洋观测与作业的重要技术装备，耐压壳是潜水器的核心结构部件。论文介绍了国内外潜水器的发展概况，对不同类型潜水器耐压壳的结构形式、材料选用，强度与稳定性设计计算方法等进行综述，展望潜水器耐压壳研究和应用的方向。

本文对考虑椭圆度和腐蚀模型的水下耐压结构强度和稳定性进行了数值仿真研究。首先利用仿真软件建立了考虑椭圆度和腐蚀效应的水下环肋圆柱壳结构有限元模型，并给出了考虑椭圆度和腐蚀效应的结构失效破坏条件。根据不同椭圆度建立几何模型，研究设计工况下不同椭圆度对于结构强度与稳定性的影响规律。在此基础上根据点腐蚀的孔径和深度建立点蚀几何模型，研究椭圆度和腐蚀复合缺陷对于结构强度与稳定性的影响规律。研究表明，应力集中随着椭圆度的增大而显著增强；椭圆度与腐蚀同时存在时，椭圆度在结构的应力分布中占主导作用；在椭圆度腐蚀复合缺陷模型中不同位置缺陷对模型整体屈曲载荷影响较小。

针对合拢端口含初始几何缺陷的环肋圆柱壳结构在形状矫正后装配产生的初应力场问题,在考虑由大变形引起的几何非线性的前提下,研究初应力场对环肋圆柱壳结构强度及稳定性的影响.采用试验方法,获得典型环肋圆柱壳在端口位移载荷下的结构应力;同时利用ANSYS软件构建含初始几何缺陷的环肋圆柱壳有限元模型并计算得到初应力场;通过试验结果与计算结果的对比验证数值仿真的有效性;进一步通过弧长法对含初始几何缺陷及初应力场的水下耐压结构的强度与稳定性进行求解.分析表明:受静水外压作用的水下耐压结构在考虑初始静应力场后,其极限承载能力出现小幅下降,结构失稳波形规则性降低,但破坏位置未发生变化.

将水下无人潜航器耐压结构作为应用背景，为对比椭球形薄壳与圆柱形薄壳承载差异，以应力和弹性稳定性作为典型力学性能指标进行对比。基于第四强度理论，以Mises应力作为典型应力开展数值计算，同等重量下椭球薄壳应力峰值较圆柱薄壳应力峰值小4%左右。以等容积、等重量为前提，基于ISIGHT平台调用Ansys，采用NSGAⅡ优化算法开展椭球薄壳弹性稳定性优化，同等重量、同等有效容积下，椭球薄壳稳定性较圆柱壳提升1.78%～6%；仅要求同等容积时，椭球薄壳稳定性较圆柱壳最大提升约200%。研究成果可为超大潜深潜器耐压结构选型提供借鉴。

针对设计过程中计算保守与试验难度大等问题，对耐压舱进行结构设计，在满足结构强度和稳定性要求的前提下，基于Workbench中的Design Exploration对耐压舱简化模型进行多目标优化分析。采用最佳填充空间设计（OSF）试验法得到优化变量的样本空间，利用神经网络构建优化响应面模型，并基于多目标遗传算法（MOGA）在回归模型中的应用，得到优化设计尺寸。经过仿真验证表明，优化后的耐压舱在强度和稳定性较好的前提下，质量和体积显著减小，实现了轻量化设计。

为提升潜水器耐压壳水下结构的综合性能,需聚焦于多目标优化设计研究,从而实现质量、强度和稳定性的协同提升。该文采用参数化分析流程对初始环肋耐压壳方案展开研究,通过最优拉丁超立方设计法进行采样,探讨设计变量对目标响应的影响;建立了高精度响应面模型及相应的多目标优化模型,进而通过第二代非支配排序遗传算法（non-dominated sorting genetic algorithm II,NSGA-II）对耐压壳多目标优化求解。研究表明：4组优化方案中,A、C方案分别减重7.3 kg和6.6 kg,B、D方案的极限强度分别提高0.177 MPa和0.031 MPa,由此证明结合响应面模型和遗传算法的多目标优化方法能有效提升潜水器耐压壳的性能,为深海探测装备的设计提供参考。

为提高无人潜水器的总体性能和设计效率，本文以一型无人潜水器的主体为研究对象，研究了主体结构的外形阻力、耐压壳体的分析方法，设计了参数化分析流程。针对结构分析和阻力分析软件进行了二次开发，实现了基于参数化的自动计算与分析，在此基础上选取主体结构外形阻力和耐压结构样本点进行了分析，进一步建立了基于近似模型的阻力和结构分析模型及无人潜水器主体多学科多目标优化设计模型。利用第二代非支配排序遗传算法进行了优化求解，选取了部分方案与初始方案进行了对比。结果表明：优化结果明显，为无人潜水器主体设计提供了依据。

大深度载人潜水器往往采用开孔耐压球壳作为其主要的承压结构,球壳开孔加强结构的优化设计，对减轻球壳重量，提高球壳承载能力具有重要意义。本文介绍拓扑优化的方法以及耐压球壳优化设计的基本流程，以4 500 m耐压球壳为研究对象，基于 Hyperworks和Workbench软件，建立了耐压球壳的有限元模型，进行静力分析，并根据结果对球壳的开孔加强结构进行拓扑优化和尺寸优化，得到最优的加强形式。优化结果表明，优化后的耐压球壳的刚度和承载能力得到显著提高。

… pressure vessel hull development over the last 50 years and uses the lessons learnt, to develop a composite pressure hull concept for a shallow diving hull, … the composite pressure hull. …

… This indicates that these design rules need to be updated … strength of spherical pressure hull under external pressure. This … and ultimate strength of spherical pressure hulls is carried out …

The design of the pressure hull, one of the most important components, has great significance for improving the performance of autonomous underwater vehicles (AUVs). In this paper, a …

This paper describes design methods for the plastic hull of an Unmanned Underwater Vehicle (UUV), with a particular focus on its cylindrical body and nearly spherical domes at the ends. With the proposed approach, the methodologies reported in the literature were compared, and suitable modifications and improvements were investigated and implemented to extend the classical theories and data to this case study. The investigated underwater vehicle, named FeelHippo, was designed and assembled by the Department of Industrial Engineering of the University of Florence. Its main hull is composed of an extruded PMMA (PolyMethyl MethAcrylate) cylinder and two thermoformed PMMA domes. Breakage of the hull results in destructive phenomena, namely, yielding and buckling. An experimental campaign and FEM (Finite Element Method) analysis were carried out to complete the theoretical study, and the collapse pressures were compared with the derived design values. In conclusion, the proposed innovative method is a lean and effective technique for designing underwater hull domes and predicting the collapse pressures.

PurposeThe main objective is to develop a new design methodology for pressure hulls, prioritizing steel weight reduction without compromising structural safety. Genetic algorithms (GA) will be employed to optimize the structural weight of the hull of a pressure vessel, considering the Det Norske Veritas (DNV) standard formulation. This includes optimizing both the scantling of the pressure hull and the dimensions of the frames while complying with constraints based on the DNV regulation: nominal, over-immersion and collapse pressures. The proposed solution will be analyzed using finite element analysis (FEA) to verify that the obtained scantlings meet the design requirements.Design/methodology/approachAn optimization of the design parameters of the structure of a pressure hull based on GA is proposed. The starting point is individuals randomly generated by combining the different values that each parameter will take. The surviving designs will be required to meet DNV standards and will be ranked according to the structural weight of each design. Prevailing will be those genes that make designs that comply with the standards and are less heavy. Finally, the feasibility of the design proposed by the GA will be tested by FEM.FindingsThe structural integrity of the design resulting from the application of GA (which complies with DNV regulations) has been evaluated by means of FEM considering different constructive defects. In summary, the proposed methodology combined with GA provides a preliminary design of the pressurized hull in a fast way, ensuring compliance with the structural requirements according to the current regulations. Furthermore, this design is optimized in terms of its own weight. The reduction in structural weight provides a reserve of buoyancy that can be used to increase other weight categories, thus extending the operating time of the pressure vessel.Originality/valueThis novel approach allows to quickly obtain a preliminary design of a pressure hull structure optimized for minimum weight and ensuring compliance with classification societies. The proposed methodology provides the user with a preliminary design with lower material cost and allows the increase of other weight items.

Recently, submersible pressure hulls with fiber-reinforced multilayer constructions have been developed as substitutes for classical metallic ring-stiffened pressure hulls. The strength and stability is its top priority. In this paper, the optimum design of elliptical composite deep-submerged pressure hull under hydrostatic pressure is investigated based on the finite element analysis to minimize the buoyancy factor of the submersible pressure hull according to the design requirements. Minimize the buoyancy factor of a submarine pressure hull under hydrostatic pressure is proposed as an objective function and the constraints based on the failure strength and the buckling strength of the hulls are considered. The thickness and the fiber orientation angles in each layer, the radii of the ellipse, the stringers dimensions and the operating depth are taken as design variables. Additionally, a sensitivity analysis is performed to study the influence of the design variables up on the Tsai-Wu failure. Results of this study provide a valuable reference for designers of composite underwater vehicles.

… weight of the pressure vessel must become very light. … for the design of ceramic pressure vessel, and ceramic pressure vessels … new concepts for the design of ceramic pressure vessels. …

This paper describes an optimization study of a spherical composite submersible pressure hull employing a genetic algorithm (GA) in ANSYS. A total of five lay-up arrangements were optimized for three unidirectional composites carbon/epoxy, glass/epoxy, and boron/epoxy. The minimization of the buoyancy factor (B.F) was selected as the design optimization objective. The Tsai-Wu and Tsai-Hill failure criteria and buckling strength factor (λ) were used as the material failure and instability constraints. To determine the effect of geometric non-linearity and imperfections on the optimized design, a non-linear buckling analysis was also carried out for one selected optimized design in ABAQUS. The non-linear buckling analysis was carried out using the modified RIKS procedure, in which the imperfection size changed from 1 to 10 mm. A maximum decrease of 65.937% in buoyancy factor (B.F) over an equivalent spherical steel pressure hull was computed for carbon/epoxy. Moreover, carbon/epoxy displayed larger decreases in buoyancy factor (B.F) in the case of 4 out of a total of 5 lay-up arrangements. The collapse depth decreased from 517.95 m to 412.596 m for a 5 mm lowest mode imperfection. Similarly, the collapse depth decreased from 522.39 m to 315.6018 for a 5 mm worst mode imperfection.

This paper outlines the design and testing process of the hull of a deep small Autonomous Underwater Vehicle (AUV), rated at 2000m depth. Many existing AUV pressure housings use aluminum or other isotropic traditional metals, instead of composites due to the complexities of the design of composites at such big load. The research at hand explains the process of design starting from setting the geometrical constraints for the design to mass production. To the best of the authors’ knowledge, none of the previous studies has presented such detailed description of the work. Carbon fiber reinforced epoxy material was chosen thanks to its high strength-to-weight ratio and similarity of its compressibility to sea water. Material characterization was performed to obtain the material properties under loading conditions using a modified method of the Combined Loading Compression testing technique. A specific fixture was designed and manufactured to test filament-wound tubes. An analytical model was developed using MATLAB, a finite element model was created using ABAQUS, and the results of the two models were compared. A set of recommendations was introduced for the stacking sequence to provide the lowest possible stresses, regardless on the diving depth of the vehicle. Afterwards, a quality control set of tests was conducted, including seawater absorption under high pressure and void analysis using destructive and non-destructive tests. Pilot samples were manufactured and tested in a pressure vessel, where it was cycle-tested and inspected using visual and ultrasonic testing. Other samples were fail-tested and showed a failure at ~93% of the expected failure load. Such range can be considered good to provide safe operation for the vehicle at the designated depth, given that the factor of safety included covers more than 7% of the failure load. The proposed design methodology has shown that CFRE can be safely used even at such high depths.

Abstract The design of structures made of laminated composites greatly depends on the fiber orientation angle and the number of ply layers. In the present study design optimization of composite submerged pressure hull under 3 MPa hydrostatic pressure, which corresponds to 300 m depth, is carried out. The number of layers and orientation angles are optimized for layups [0m/90n/0o], [10m/-10n/90o/-10p/10q], [α1m/α2n], [α1m/α2n/α3o] and [α1m/α2n/α3o/α4p/α5q] using three unidirectional composite materials, Carbon/Epoxy, Glass/Epoxy, and Boron/Epoxy. The optimization process is carried out in ANSYS Workbench using a Genetic Algorithm. Minimizing the buoyancy factor is used as the objective function of the optimization. The constraints on the optimization process are Tsai-Wu and Tsai-Hill failure criteria and buckling strength factor. Optimization study is also conducted for one selected layup configuration using ABAQUS and ISIGHT. Additionally, a sensitivity analysis is also carried out to study the effect of various design parameters on the optimum design of composite submerged pressure hull.

… favorable for the submersible pressure hull design process. 0 … to study the minimum weight design. This study also used … favorable for the submersible pressure hull design process. …

… mass of the pressure hull. Therefore, this study proposes a design method for the pressure hull of … Topology optimization design of the pressure hull is realized with the variable density …

As the most critical component of a deep manned submersible, the manned pressure hull provides a safe living space for pilots and scientists under the deep sea pressure, and its weight occupies almost 1/3 total weight of the manned submersible. So the pressure hull should be designed to have enough strength and should be as light as possible. However, a comparison of the current available design rules from various classification societies indicated significantly different results among these design rules and many existing spherical pressure hulls are found to be not in compliance with most of the current design rules. This indicates that current design rules need to be updated and unified, similarly to the Common Structural Rules for tankers and bulk carriers. To update the design rules, a systematic study is carried out. Then, a new design standard based on this study is proposed to the China Classification Society (CCS) for consideration of updating their rules. The main purpose of this paper is to briefly summarize the study on this new design standard and to present the structural optimization of the manned spherical pressure hull of a new 4500-m rating manned submersible based on this new standard.

… Minimize the buoyancy factor of the submersible pressure hull … buckling strength of the pressure hull, incorporating both the … design variables on the optimal structural strength design. …

… This study compares design standards for shallow water spherical pressure hull constructed from steel. The thicknesses obtained by different design methods are compared with those …

… a pressure hull option (except perhaps in small-diameter vehicles, eg torpedoes, and where high temperature operation is necessary, eg in the region of a power plant). FRP, therefore, …

This study addresses the limitations of buoyancy factor and compensation capacity in pressure hulls for full-ocean-depth underwater gliders operating in extreme deep-sea conditions. A novel lightweight multifunctional composite structure pressure hull (CSPH) is proposed, utilizing a carbon fiber cylindrical shell as the primary load-bearing structure and silicone oil as the buoyancy compensation medium. A mechanical model of the carbon fiber cylindrical shell under hydrostatic pressure was developed based on three-dimensional elastic mechanics theory. Furthermore, a comprehensive performance evaluation model for the CSPH was created, incorporating both the buoyancy factor (Bf) and buoyancy fluctuation coefficient (fB). The NSGA-II optimization algorithm was employed to simultaneously minimize Bf and fB by co-optimizing the carbon fiber ply parameters and the silicone oil volume (VC). This optimization resulted in a Pareto optimal solution balancing buoyancy and compensation performance. The accuracy of the mechanical model and optimization results was validated through finite element analysis and pressure testing. The results show that, compared to traditional metallic pressure hull designs, the CSPH reduces the buoyancy factor by 48% and enhances buoyancy compensation performance by 2.5 times. The developed CSPH has been successfully deployed on the “Sea-Wing 11000” full-ocean-depth underwater glider, significantly improving its endurance and motion stability for long-term deep-sea observation missions.

The design of deep submersible pressure hull's structural is one of the core technologies of submersible development of human history. Submersible pressure hulls with fiber-reinforced multilayer constructions have been developed in the recent years as substitutes for classical metallic ring-stiffened pressure hulls; strength and stability are its top priority. This paper investigates the optimum design of a composite elliptical deep-submerged pressure hull under hydrostatic pressure to minimize the buoyancy factor of the submersible pressure hull under constraints on the failure criteria and the buckling strength of the hulls to reach the maximum operating depth. The thickness and the fiber orientation angles in each layer, the radii of the ellipse, and stringers dimensions were taken as design variables and determined in the design process. The optimization procedures are performed using commercial finite element analysis software ANSYS. Additionally, a sensitivity analysis is performed to study the influence of the design variables on the structural optimum design. Results of this study provide a valuable reference for designers of underwater vehicles.

In order to develop the knowledge base necessary to design deep sea pressure vessels, it is essential to understand the full chain from design and manufacturing through nondestructive testing (NDT) and characterization to long-term behavior under hydrostatic pressure. This paper describes results from European and national research programs focusing on the use of composites for underwater applications over the last 20 years. Initial tests on small glass/epoxy cylinders were followed by large demonstration projects on carbon/epoxy cylinders with implosion pressures of up to 600 bar, corresponding to 6000 m depth. Numerical modeling has enabled end closures design to be optimized for test performance. Thin and thick wall cylinders have been tested under quasi-static, and long-term loading. Both thermosetting and thermoplastic matrix composites have been tested to failure, and the influence of defects and impact damage on implosion pressure has been studied. These deep sea exploitation and exploration studies were performed for oceanographic, military, and offshore applications, and extensive data are available. The aim of this paper is to indicate existing results, particularly from European projects, in order to avoid costly repetition.

… pressure vessels has been studied. Firstly, an analytical solution of the autofrettage pressure of the spherical external pressure … autofrettage pressure of the spherical hull for deep-sea …

… FEA of the pressure vessels for a 6000 meters depth-rated deep-sea unmanned underwater … pressure vessels by using it. The safety of two pressure vessels, the main pressure vessel …

… gravity and enlarges its pressure tolerance, had been … pressure vessels for deep-sea operation. As the first step, the spherical pressure vessel of ceramics was studied for deep-sea …

Abstract This paper explores the potential of hydrogen as an energy carrier for deep-sea applications. Finite element analysis of a type III pressurised cylinder to the intended working pressures of 300 bar internal and up to 600 bar external were carried out for different designs and safety factors. Design parameters such as helical angle, liner, helical, and hoop thicknesses were studied and optimised. A buckling analysis was carried out for the optimised designs and recommendations to increase the maximum allowable external pressure are given.

Abstract Oceans are areas on our planet which remain largely unexplored. This is mainly due to the considerable challenges involved in underwater exploration. So far the majority of surveys are carried out using Remotely Operated Vehicles (ROVs) and Automated Unmanned Vehicles (AUVs). These vehicles, despite their impressive capabilities, have several limitations, especially in terms of their operational endurance. Moreover, a very small number of ROVs have been qualified for operations in depths beyond 6 km. The use of ROVs in ocean trenches involves extremely complex operations and is not free of risk. The deepest known point is Challenger Deep at the Mariana Trench in the Pacific Ocean, with a maximum depth of just under 11 km. Only a handful of manned and unmanned missions have managed to reach this depth since Piccard's mission in 1960, on-board the bathyscaphe Trieste. Herewith we report on the finite elements analysis of type I pressure vessels for hydrogen storage to be used in future AUVs with long endurance capability for ultra-deep exploration.

… This paper focuses on the buckling of titanium alloy … buckling of geometrically perfect hulls were examined numerically and verified analytically in linear range. The nonlinear buckling of …

With the increasing application and study of lightweight and high strength fiber reinforced polymer composites in ocean industry, the structural failure problem of composite pressure hulls has attracted great attention from many researchers in China and globally. Analysis of the structural failure mechanisms is foundational to the design of deep-sea composite pressure hulls, since nowadays the design rules of pressurized vessels is mostly formulated according to their failure modes. Hence, this paper aims to review the research on the structural failure of composite pressure hulls in deep sea settings. First of all, the applied research status on composite material in marine equipment is analyzed, including inspection modalities for composite pressure hulls. The review then focuses on the three main failure modes, namely overall buckling, material failure and snap buckling of the deep-sea composite pressure hulls. The study identifies further problems of composite pressure hulls to be solved through the application of the deep sea equipment research, aiming to provide a reference for the study of mechanical behavior, ultimate strength computation, and design of thick composite pressure hulls for deep sea equipment.

This paper reports on theoretical and experimental investigations into the buckling characteristics of a series of six ring-stiffened circular cylinders that experienced general instability when subjected to external hydrostatic pressure. Each study used between 3-5 designs with the same internal and external diameters, but with different numbers and sizes of ring-stiffeners. Four used designs that were machined to a high degree of precision from steel, while the other two were machined from aluminium alloy. The theoretical investigations focused on obtaining critical buckling pressure values, namely Pcr, for each design from the well-known Kendrick’s Part I and Part III theories, together with an ANSYS finite element prediction. The thinness ratio λ1, which was originally derived by the senior author, was calculated together with a dimensionless quantity called the plastic knockdown factor (PKD), for each model. The plastic knockdown factor was calculated by dividing the theoretical critical buckling pressures Pcr, by the experimental buckling pressures Pexp. The thinness ratio was used because vessels such as these, which have small but significant random out-of-circularity, defy “exact” theoretical analysis and it is because of this that the design charts were produced. Three design charts were constructed by plotting the reciprocal of the thinness ratio (1/ λ1) against the plastic knockdown factor (Pcr / Pexp), using results from Kendrick Part I, Kendrick Part III, and ANSYS. Comparison of the results obtained using Kendrick’s theories and experimentally obtained results was good.

… for linear-elastic analysis, Finite Element Analysis has been used, and for buckling analysis, the general buckling pressure and the partial buckling pressure have been verified by ABS …

… vessels for deep-sea service under external hydrostatic pressure (worst-case buckling) and … burst performance alongside the geometry's known buckling advantage over cylinders. The …

… Spherical pressure-resistant shells, as a universal structural component of deep-sea submersibles, … predictions and the precision of reliability assessments for deep-sea spherical …

Abstract Thin spherical pressure hulls are used as a human occupancy in deep water applications. DNV and other standards specify the imperfection allowed for pressure hulls. Numerical analyses are carried out to find the buckling pressure for both perfect and imperfect thin spherical pressure hulls, considering the geometric and material non-linearities. It is observed that there is a huge variation in the elastic and inelastic buckling pressure in perfect spherical pressure hulls. Moreover, if the manufacturing imperfections are considered in the inelastic numerical analysis, still there is a reduction in the buckling pressure. Design criteria, for deep water pressure hulls, is that both buckling pressure and yield pressure must be greater than the design pressure. In the elastic analysis, if t/D > 0.006 buckling pressure is always greater than the yield pressure whereas in the inelastic analysis, the buckling pressure is falling below the yield pressure for all t/D ratios. Hence, inelastic numerical analysis with manufacturing imperfection has to considered in the design of deep water spherical pressure hulls of manned submersibles.

本文以深潜装备材料应用需求为导向，深入研究当前各国主要耐压壳体材料和固体浮力材料的应用现状及发展趋势。通过对材料的机械性能、化学成分等指标进行对比分析，提出了当前深潜材料发展遇到的系列技术瓶颈问题和相应解决方案。通过深入分析各国深潜材料的关键技术和性能指标，发现其总体趋势均向着高强度、低密度方向发展，但在尝试进一步提升材料性能指标时，却导致材料出现韧度降低、焊接性能差、吸水率增高等系列缺陷。因此，尝试研发各项性能优异的空心陶瓷和纳米复合材料等新型材料。陶瓷基复合材料和碳纳米管增强浮力材料以其优异的结构强度和抗压性能，必将大幅提升深潜装备的总体性能指标，成为深潜器的重要选材。

深海潜水器耐压壳材料的服役可靠性直接关乎深潜器的作业安全，钛合金因其优异的深海环境服役性能成为制造深潜器耐压壳的关键材料。本文从深潜器用钛合金的种类出发，详细介绍了钛合金室温蠕变、低周疲劳及保载疲劳等主要失效形式的最新研究进展，归纳了钛合金保载疲劳的主要影响因素、微观损伤机制及寿命预测模型，以期为新型高强低保载效应的高性能钛合金研发提供参考。最后，提出了目前深潜器用钛合金构件服役可靠性评价亟待解决的若干问题和未来的研究方向。

全海深水下机器人的潜浮过程中环境物理参数存在显著变化，重力和浮力状态随之改变。通过地球重力加速度及其异常值和深渊剖面海水温度、盐度、压力和密度的计算和分析，结合构成全海深水下机器人不同结构、材料的部件在环境温度、压力变化下的体积变化规律，得到了全海深水下机器人潜浮过程中的浮力变化曲线。结果显示：深渊剖面的重力异常对合力的影响不超过1 N；对于质量为吨级的、由浮力材和玻璃球壳为主要构成的全海深水下机器人，潜至11 km时浮力将增加204 N。为全海深水下机器人在海沟深渊潜浮过程中的静力平衡变化提供了精确的预报。

面向海斗号全海深水下机器人万米深潜对重力与浮力的匹配性需求，研究其跨越万米深度过程中因体积变化而引起其浮力变化的海洋环境因素影响机理，分析各海洋环境因素对海斗号重力与浮力匹配的影响；基于机理分析法，构建海斗号全海深水下机器人综合体积弹性模量数学模型，为面向不同深度的作业任务提供浮力配平依据，实现其对不同深度剖面的环境适应性；利用海斗号不同下潜深度的海上试验数据，验证了本文构建的海斗号全海深体积弹性模量模型的准确性，为全海深水下机器人深度剖面环境适应性实现方案提供了模型参考和理论依据。

载体框架作为载人潜水器的重要部件，除了满足总布置的要求，还要具有足够的强度、刚度和稳定性。以某型载人潜水器载体框架为例，依据《潜水系统和潜水器入级与建造规范》，采用总体桁架梁单元模型和局部精细化模型联合分析的方法，对载体框架结构强度、稳定性和刚度进行分析，并通过载体框架极限承载试验的验证。结果表明：载体框架经受了极限承载试验的考核，框架设计合理；试验结果与计算结果相吻合，说明采用总体桁架梁单元模型和局部精细化模型联合分析的方法，可为潜水器载体框架的结构计算和优化设计提供参考。

为解决大型潜水器框架极限承载试验实施困难的问题，本文设计一种用于潜水器载体框架极限承载试验的通用试验装置。首先基于通用性的设计理念完成了试验装置的结构和功能设计，利用有限元程序对结构在极限载荷作用下的强度和刚度进行分析和结构优化，最后通过某载体框架承载试验考核验证。结果表明：该试验装置通过了功能性和结构安全性考核，提高了加载精度和工作效率，解决了大型潜水器框架起吊承载试验实施困难的问题，填补了国内该类通用性试验装置的空白。

… Deep-sea pressure vessel operates in extreme marine environments characterized by high pressure, … for high-strength steels used in deep-sea pressure vessel hulls. In addition to high …