载人潜器耐压球壳参数化设计与稳定性分析

载人潜器耐压球壳设计的关键是稳定性分析,在针对CATIA进行了二次开发的基础上,实现了CATIA软件参数化模型与有限元分析软件ABAQUS之间的通信,采用ABAQUS中的python语言编程实现了对变参数模型的自动分网,采用惯性释放进行了边界设置,在研究了基于弧长法的稳定性求解方法的基础上,选取MT-1模型进行了稳定性求解方法的有效性验证,最后将参数化设计及稳定性求解方法应用到实际设计中,提高了耐压球壳设计效率。     

球柱壳耐压舱体极限承载力研究

耐压舱设计是水下机器人的核心技术之一,其极限承载力研究是核心中的核心。针对球壳封盖加柱形壳体耐压舱,现行标准对于初始导入缺陷数值的确定往往过于保守,对于耐压舱体数量较多的无人潜水器来说,过大的设计质量是总体设计所无法接受的。首先采用装配体整体建模策略,建立复合屈曲的受力模型,将三大非线性影响因素同时引入到极限承载力研究中,提升了计算精度。然后分别针对确定性缺陷和非确定性缺陷结构开展极限承载力研究。最后,提出以0.23%的初始缺陷导入尺度作为球壳封盖加圆柱壳体的耐压壳体缺陷导入参数,给出了导入尺度的计算方法,并借助水压试验对上述参数的准确性进行验证。     

轻载作业型载人潜水器耐压球壳设计

耐压球壳是载人潜水器的关键部件,对于载人潜水器的安全性、总体性能等诸多方面均有重要的影响。针对轻载作业型HOV耐压球壳的设计,确定了壳体材料、结构形式和主要尺度,完成了基于规范的耐压球壳强度校核和稳定性分析,设计了开孔加强结构,完成了基于有限元耐压球壳模型强度校核。最后,在考虑了材料非线性、初始缺陷等因素的基础上,采用弧长法完成了耐压球壳的稳定性分析。结果表明耐压球壳的设计方案满足规范要求,为深水轻载作业型载人潜水器耐压球壳的设计提供了参考。     

水下滑翔器耐压壳体的设计与优化

采用特征值屈曲分析方法对水下滑翔器耐压壳体的结构参数进行了分析,计算了结构参数在不同取值情况下壳体的临界失稳压力,在分析比较计算结果的基础上,确定了耐压壳结构参数的最优数值。计算结果表明,优化设计得到的壳体即能满足抗压稳定性和机械强度要求,又最大限度地减轻了壳体的重量,与最初的设计方案相比,壳体重量减轻了1.51 kg,同时也使壳体内部空间得到了加大,其中中间段内部空间直径扩大了8 mm。     

深海无人遥控潜水器耐压电子舱结构设计与分析

研究深海无人遥控潜水器(ROV)耐压电子舱结构设计中涉及的力学分析技术。利用有限元数值分析方法校核耐压电子舱在深水条件下的强度、刚度与稳定性。根据深海耐压电子舱受力特点,优化其结构形式和尺寸,获得最优结构拓扑构型。对于耐压电子舱上下壳体接合面间接触问题,将非线性接触分析和简化分析法的计算结果进行比较。探讨加工误差与初始缺陷对耐压电子舱力学性能的影响。计算结果表明,耐压电子舱结构优选设计方案满足力学性能和重量要求,并且对加工误差与初始缺陷的影响不十分敏感。     

深海潜器耐压圆柱壳结构计算和校核方法研究

文中比较了中美两国潜器规范中各特征量的计算方法和校核准则,分析了异同点,并给出数值算例。针对潜器特性,对目前我国潜器规范中可能需要修改的地方进行了初步分析。     

含缺陷球柱组合壳极限承载能力分析

球柱组合壳是单壳体潜艇耐压船体结构的主要形式,其结构在极限载荷作用下的极限承载能力和变形是评估潜艇结构安全性的重要指标。 在试验模型基础上,根据三维实测初挠度数据建立含缺陷的球柱组合壳有限元模型,将极限强度计算结果与试验数据对比分析,结果表明:上述数值方法准确可靠,且缺陷的引入对于工程上潜艇结构的极限承载能力评估具有实际意义。     

海洋电缆弯曲加强器参数化设计与分析

为建立海洋电缆弯曲加强器参数化设计方法,使用有限元模型进行了弯曲加强器设计参数研究.基于海缆及其弯曲加强器的几何结构及受力特点,建立了基于多相耦合梁单元的平面有限元模型,可以计算并分析海缆及其弯曲加强器在一定角度的张力作用下的形变与等效应力分布.通过多个案例系统性地分析了弯曲加强器的主要设计参数,即根部直径、锥体段长度及材料弹性模量,对海缆弯曲挠度、曲率及等效应力分布的影响.文中原创性地提出了弯曲加强器组合设计参数φ(t,L,E).通过定量分析确定了其与海缆最大曲率之间的近似线性关系,并由此设计了参数化的弯曲加强器设计流程.通过设计实例验证了组合参数与海缆最大曲率之间关系的准确性和参数化设计流程的有效性.     

初始缺陷对深海载人潜水器耐压球壳塑性稳定性影响

载人深潜器耐压球壳是中厚度壳结构,当结构发生失稳时,球壳结构的局部部位因为材料达到屈服极限而发生了塑性变形.将有限元分析与经典理论相结合,研究弹性屈曲模态缺陷、局部缺陷以及球壳整体圆度和厚度偏差对中厚度球壳结构的塑性稳定性的影响.计算结果表明中厚度球壳结构对初始缺陷并不很敏感,对球壳结构当局部缺陷范围刚好达到临界弧长时结构的承载力最弱.通过缺陷结构和完善结构的极限承载力比较,提供了初始缺陷影响曲线.     

海底管道泄漏参数灵敏度分析

文章利用FLUENT软件中的欧拉模型,对海底管道油气两相泄漏进行仿真,分别模拟没有气体扩散及有气体扩散的情况,考虑了气泡尺寸、海流、泄漏率及油的种类等因素对油气运动形态的影响,采用灵敏度理论,计算出油在水下漂移距离及到达水面的时间的灵敏度。计算结果表明,泄漏率对油到达水面的时间的灵敏性最高,海流对油在水下漂移距离的灵敏性最高。该灵敏度分析结果可为管道泄漏应急决策提供理论依据。     

Postbuckling of Imperfect Stiffened Cylindrical Shells Under Combined External Liquid Pressure and Axial Compression

- posthuckling analysis is presented for the stilTened cylindrical shell of finite length subjected to combined loading of external liquid pressure and axial compression. The formulations are based on a boundary layer theory of shell buckling, which includes the effects of nonlinear prebuckling deformations, nonlinear large deflections in the postbuckling range and initial geometrical imperfections of the shell. The "smeared stifl'cner" approach is adopted for the stiffencrs. In the analysis a singular perturbation technique is used (o determine the interactive buckling loads and the postbuckling paths. Numerical examples cover the performance of perfect and imperfect, stringer and ring stiffened cylindrical shells. Typical results arc presented in the dimcnsionless graphical form.     

载人潜水器圆柱形耐压壳体的优化设计研究

采用分枝定界法和序列二次规划方法,对载人潜水器圆柱形耐压壳体的重量最小化进行了研究.设计变量是壳板的厚度、肋骨的型号、间距和数量,讨论了下潜深度、材料几何参数对重量以及其它特征量的影响.算例计算表明,下潜深度越大,屈服极限越高的材料重量减轻越明显.对于大深度而言,选用高屈服极限材料,可以使得材料能够充分利用.文中还对结构重量占排水量比例随深度变化的情况进行了研究.     

Parametric Analysis of A Submerged Cylindrical Shell Subjected to Shock Waves

In this study,an FEM-SBFEM(scaled boundary finite element method)coupling procedure proposed by Fan et al.(2005)is adopted to obtain the dynamic responses of a submerged cylindrical shell subjected to plane step or exponential acoustic shock waves.The coupling procedure can readily be applied to three-dimensional problem,however for clarity,the problems to be presented are limited to two-dimensional domain.In the analyses,the cylindrical shell is modeled by simple beam elements(using FEM),while the effects of the surrounding infinite fluid is modeled by the SBFEM.In it,no free surface and seabed are involved.Compared with Fan and his co-authors' works,the FEM-SBFEM coupling procedure is further verified to be feasible for shock waves by benchmark examples.Furthermore,parametric studies are performed and presented to gain insight into effects of the geometric and material properties of the cylindrical shell on its dynamic responses.     

Dynamic Buckling of Elasto-Plastic Cylindrical Shells Under Axial Fluid-Solid Impact Load

- The dynamic buckling of elasto-plastic cylindrical shells under axial fluid-solid impact is investigated theoretically. A simplified liquid- gas- structure model is given to approximately imitate the problem. The basic equation of the structure is derived from a minimum principle in dynamics of elasto-plastic continua at finite deformation, and the flow theory of plasticity is employed. The liquid is incompressible and the gas is compressed adiabatically. A number of numerical results are presented and the characteristics of the buckling behavior under fluid-solid impact are illustrated.     

Vibration and Acoustic Radiation from Orthogonally Stiffened Infinite Circular Cylindrical Shells in Water

Based on the motion differential equations of vibration and acoustic coupling system for thin elastic shells with ribs, by means of the Fourier integral transformation and the Fourier inverse transformation, as well as the stationary phase method, an analytic solution, which has satisfying computational effectiveness and precision, is derived for the solution to the vibration and acouslic radiation from a submerged stiffened infinite circular cylinder with both ring and axial ribs. It is easy to analyze the effect of stiffening supports in the acoustic radiation field by use of the formulas obtained by the pre-sented method and corresponding numerical computation. It is shown that the axial-stiffeners can improve the mechanical and acoustical characteristics. Moreover, the present method can be used to study the acoustic radiation mechanism of the type of structure.     

Viscoplastic Torsional Buckling of Cylindrical Shell

- The Bodner-Partom constitutive equation is used to study the viscoplastic torsional bucklingof perfect cylindrical shell. By treating the viscoplastic shell as an orthotropic shell at each moment and neglecting the inertia term, the critical torque is determined from a set of homogeneous linear equations. The strain rate sensitivity is mainly discussed in the present paper.     

The Influence of Residual Stress on Plastic Buckling of Cylindrical Shells

-This paper adopts approximate formulas for residual stresses caused by cold bending for plates with stress-strain curve form a = K n. A typical distribution of the longitudinal residual stress due to welding is also assumed. The effects of residual stress due to cold bending and welding on plastic buckling of axially compressed cylindrical shells are studied by the finite element method.     

Impact Buckling and Post-Buckling of Elasto-Viscoplastic Cylindrical Shell Under Torsion

The dynamic torsional buckling and post-buckling of elasto-plastic circular cylindrical shell isstudied.By the usage of the Bodner-Partom constitutive relation,the present visco-plastic problem is treat-ed as an orthotropic elastic problem.Based on the nonlinear large deflection shell therory,the governingdynamic buckling equation is solved by the Runge-Kutta method,and the critical buckling stress is deter-mined by the B-R criterion.The present paper is mainly focused on the imperfection sensitivity,the strainrate sensitivity,and the dynamic post-buckling characters for the shell loaded dynamically with a constantshear strain rate.Numerical results show that the critical shear stress and imperfection sensitivity will in-crease with the increase of strain rate.It is found that the elastic buckling stress is more sensitive toimperfection than the visco-plastic buckling.The present research also reveals some dynamic post-bucklingcharacters for the cylindrical shell,and it is shown that the shell will vibra