环-球型端部舱壁结构强度与变形分析

以弹性回转壳理论为基础,推导圆锥壳与球形壳体的刚度矩阵与载荷列阵,建立了静水压力下考虑大挠度影响的环-球型端部舱壁强度与变形的理论计算方法。算例表明该方法与有限元数值方法计算结果相当吻合,也表明大挠度效应对该结构的强度与变形有一定的影响。研究表明,对于类似的回转壳体组合结构,进行解析分析是可行的,而且比常规的有限元方法更加准确和实用。研究结果对潜艇端部舱壁与压力容器球形封头设计具有重要指导作用。在现有研究的基础上,可以将该方法的应用范围推广至轴对称压力作用下的环-球型回转壳结构。     

大厚度环肋圆柱壳结构应力特性研究

环肋圆柱壳是水下工程产品中广泛采用的一种典型耐压结构。随着工作深度需求越来越深,环肋圆柱壳结构设计逐渐呈现出大厚度的新结构特征。本文以某深海无人系统耐压结构参数为例,采用理论方法和有限元仿真方法进行计算分析,研究不同厚度特征参数（t/R）下的环肋圆柱壳结构应力特性。结果表明,基于薄壳理论的解析计算方法不适用于大厚度环肋圆柱壳结构应力计算,大厚度环肋圆柱壳结构的应力特性与传统圆柱壳结构存在较大差异,在大厚度环肋圆柱壳结构设计时应综合权衡其壳板应力和肋骨应力的特性。     

潜艇耐压结构全船有限元应力分析

在对潜艇全船耐压结构有限元应力分析的基础上,又进行了各局部结构的二级甚至三级离散有限元应力分析,比较了一般环肋圆柱壳、环肋圆锥壳、环肋锥-柱结合壳、横舱壁区域结构、耐压液舱区域结构典型点应力与现有解析算法结果的差异程度,得出了一些有工程实用意义的结论.     

纵骨式双层圆柱壳结构应力计算的级数方法

对纵骨式双层圆柱壳结构应力计算方法进行了研究，在双层同心纵向加强圆柱壳假设下，建立了力学模型，利用扁壳理论以及应力函数方法建立了平衡方程，并利用梁振型函数的级数展开作为位移和应力函数的待定解，求解出内，外壳板典型部位应力，本方法计算结果与有限元计算值比较吻合，与试验测量值也吻合较好。     

潜艇耐压结构全船有限元应力分析

在对潜艇全船耐压结构有限元应力分析的基础上，又进行了各局部结构的二级甚至三级离散有限元应力分析，比较了一般环肋圆柱壳、环肋圆锥壳、环肋锥－柱结合壳、横舱壁区域结构、耐压液舱区域结构典型点应力与现有解析算法结果的差异程度，得出了一些有工程实用意义的结论。     

两端圆板封闭圆柱壳自由振动的半解析解

文章基于经典弹性板壳理论,通过解析方法导出两端圆板封闭圆柱壳自由振动的求解方程和边界条件。圆柱壳与两端圆板的连接条件由连接处的变形连续性和内力平衡关系得出。应用三角函数和Bessel函数构造该组合壳体的模态振型,对决定任意边界条件圆柱壳模态振型的八次方程的根进行了详细讨论。在MATLAB中编写固有频率的搜索程序,给出了两端圆板封闭圆柱壳自由振动的半解析解。半解析方法得到的固有频率和振型的数值结果与有限元方法计算的结果作了比较,两者几乎完全一致。该半解析方法不存在高频处理难的问题,并且计算速度远远高于有限元方法。     

玻璃钢渔船帽形骨材顶角变化对应力集中的影响

文章采用有限元方法,以玻璃钢渔船帽形骨材的剖面顶角α的值为变量,建立系列有限元模型,比较分析它们在相同载荷和边界条件作用下的计算结果,探讨顶角对根部应力集中的影响。研究表明,帽形骨材腹板与壁板连接处的应力在一定范围内,随顶角α值的增大而减小,但大于某极值以后,又会迅速增大,即帽形骨材腹板与壁板连接处的应力存在着一个最小的极值点。文章的研究方法以及所得到的规律对玻璃钢渔船帽形骨材的设计具有一定的参考价值。     

潜艇全船耐压结构有限元应力分析

本文对潜艇全船耐压结构进行了有限元应力分析，在此基础上，又进行了各局部结构的二级甚至三级离散有限元应力分析，比较了一般环肋圆柱壳、环肋圆锥壳、环肋锥－柱结合壳、横舱壁区域结构，耐压液舱区域结构典型点应力与现有解析算法结果的差异程度，得出了一些有工程实用意义的结论。     

潜艇耐压结构的稳定性分析

系统地讨论了环肋圆柱壳、环肋圆锥壳、锥-柱结合壳以及耐压液舱等结构的稳定性问题.通过大量有限元计算和理论分析,指出了有的解析法公式可用,有的要作修正,有的需要进一步探讨,有的给出了计算方法的具体建议,使正确理解和使用各种稳定性解析公式成为可能.因而本文具有重要的理论和工程应用价值.     

圆柱壳变形计算方法研究

圆柱壳的变形特性计算一直受到广泛的重视,解决这一问题的经典板壳理论解法主要有解析法、数值法和半解析法。由于环肋圆柱壳结构的复杂性,采用纯解析的方法求解非常困难。随着计算机技术的发展,有限元法在船体结构分析中已占主导地位,并已成为数值解法的典型代表。本文通过对底部简支和悬臂薄壁圆柱壳的受力状态进行分析,建立有限元模型进行仿真计算并与理论计算结果加以比对,分析不同计算方法对圆柱壳变形结果的影响。     

缩减弹性模量有限元法计算加肋轴对称组合壳的极限载荷

将缩减弹性模量的思想融入基于轴对称壳单元的有限元分析,建立缩减弹性模量有限元法,计算加肋轴对称组合壳的极限载荷。建立壳单元弹性状态、局部屈服状态和截面屈服状态的判断条件;提出弹性模量调整策略和组合壳极限状态的判断方法,实现对加肋轴对称组合壳的塑性极限分析。编制了计算程序,算例表明该方法计算时间省,计算精度较高。     

加肋轴对称壳非线性分析方法的探讨

将Sanders-Koiter几何非线性壳体理论与理想弹塑性本构关系结合,建立了加肋轴对称壳体结构的非线性有限元计算方法,并对加肋锥-环-柱组合壳塑性力学现象进行了观测,发现加肋锥-环-柱组合壳在失稳破坏时,环壳屈服厚度占壳体厚度的44%。     

马鞍形船体板冷压成形回弹数值模拟研究*

马鞍形是船体外板中比较常见的一种,在船体板的冷压成形中回弹是影响成形件质量的主要因素之一。本文针对马鞍形面的船体板进行了回弹模拟,分析了板厚和不同曲率变化条件下对回弹的影响规律,为后续的利用回弹规律进行模具补偿提供依据。     

运用弹性理论研究有限长圆柱壳声辐射的一个通用方法(英文)

A general method was proposed to study the sound and vibration of a finite cylindrical shell with elastic theory.This method was developed through comprehensive analysis of the uncoupled Helmholtz equation obtained by the decomposition of elastic equations and the structure of the solution of a finite cylindrical shell analyzed by thin shell theory.The proposed method is theoretically suitable for arbitrary thickness of the shell and any frequency.Also,the results obtained through the method can be used to determine the range of application of the thin shell theory.Furthermore,the proposed method can deal with the problems limited by the thin shell theory.Additionally,the method can be suitable for several types of complex cylindrical shell such as the ring-stiffened cylindrical shell,damped cylindrical shell,and double cylindrical shell.     

变厚度圆柱壳的最大基频设计

研究了变厚度圆柱壳自由振动的最大基频设计问题.即在任意轴对称边界条件下,寻求圆柱壳的最优厚度分布使自振基频极大化.利用半解析元方法分析轴对称变厚度圆柱壳的自由振动,将求解自振基频归为求解广义特征值方程,使变厚度圆柱壳的最大基频设计成为极大化最小特征值问题;在此基础上利用适当优化算法求解该优化模型获得变厚度圆柱壳最大基频.典型算例表明了文中方法的有效性和计算程序的快速收敛性.     

Calculation method of underwater acoustic and vibration response of cabin segment based on onshore vibration test北大核心CSCD

[Objective]This paper proposes a method for calculating the acoustic and vibration response of underwater cylindrical shell structures based on land-based vibration test results.[Methods]An axisymmetric boundary element method (BEM) is introduced to describe the radiation acoustic field of the shell. The relationship of acoustic pressure at the nodal point of the generatrix with velocity is obtained by solving the numerical solution of the boundary element integral equation, then the acoustic radiation impedance matrix of the outer surface of the shell and acoustic transfer vector (ATV) are constructed. Based on the assumption that the low-order vibration mode of an underwater cylindrical shell is the same as that of an onshore cylindrical shell, combined with the modes and acoustic radiation impedance matrix of an onshore cylindrical shell, the modal added mass and damping are calculated. [Results]The natural frequency calculation formula of the underwater cylindrical shell is established on the basis of the onshore mode, and the calculation method of underwater vibration response and acoustic radiation characteristics with the vibration response in air as input is obtained based on mode superposition method.[Conclusion ] The numerical results of a typical cylindrical shell with internal structure show that the method meets the engineering accuracy requirements. © 2023 Chinese Journal of Ship Research. All rights reserved.     

Stress concentration factors at welds in pipelines and tanks subjected to internal pressure and axial force

In this paper, analytical expressions for stress concentration factors in pipes subjected to internal pressure and axial force are derived for a number of design cases based on classical shell theory. The effect of fabrication tolerances in simple butt welds is assessed. Analyses based on classical mechanics are compared with results from axisymmetric finite element analyses for verification of the presented methodology. Stress concentration factors are presented for circumferential butt welds in pipes welded together from pipes with different thicknesses, welds at buckling arrestors, welds at flanged connections in pipelines, and welds at ring stiffeners on the inside and the outside of the pipes. It also includes stress concentration factors at end closures in pipes for gas storage. Larger pipes are fabricated from plates with a longitudinal weld. This fabrication process introduces out-of-roundness in the pipes. The actual out-of-roundness is a function of internal pressure. An analytical expression for the bending stress in the pipe wall due to this out-of-roundness is presented. The derived stress concentration factors can be used together with a hot spot stress S–N curve for calculation of fatigue damage.     

4500米级载人深潜器耐压球壳疲劳可靠性分析

采用能计及裂纹闭合以及裂纹前缘的三维约束效应的裂纹扩展预报模型对我国研制中的4500米载人深潜器钛合金耐压球壳的疲劳寿命研究。参考国外同级别深潜器下潜统计数据建立了疲劳载荷概率模型,基于响应面法开展了疲劳可靠性分析,得到了失效概率及各随机变量参数敏感性结果,对载人球壳抗疲劳设计及结构安全性评估具有一定的参考意义。     

疲劳裂纹扩展模型中表征裂纹闭合水平参数的确定

借助7075-T 6铝合金、6013铝合金以及0.45w t%碳钢的疲劳试验数据,结合上述材料的力学性能参数,通过非线性最小平方拟合方法,研究了表征裂纹闭合水平参数k对疲劳裂纹扩展率的影响。研究结果表明,对于宏观裂纹范围内的疲劳裂纹扩展,参数k只要大于某个值就对疲劳裂纹扩展率无影响;而对于小裂纹阶段的疲劳裂纹扩展,参数k对疲劳裂纹扩展率的影响较明显,因此参数k的大小主要取决于小裂纹扩展数据。依据0.45w t%碳钢疲劳试验数据,相应参数k的建议值为6 000m-1。     

Sanders中长圆柱壳理论及其在海洋工程中的应用(英文)

The cylindrical shell is one of the main structural parts in ocean engineering structures.These cylinders are mostly of medium length,which means that the radius of the cross section is significantly smaller than the length of the cylindrical shell.From the viewpoint of the shell theory,they belong to the mid-long cylindrical shell category.To solve mechanical problems on this kind of structure,especially a cracked cylindrical shell,analysis based on shell theory is necessary.At present the generally used solving system for the mid-long cylindrical shell is too complicated,difficult to solve,and inapplicable to engineering.This paper introduced the Sanders’ mid-long cylindrical shell theory which reduces the difficulty of the solution process,and will be suitable for solving problems with complicated boundary conditions.On this basis,the engineering applications of this theory were discussed in conjunction with the problem of a mid-long cylindrical shell having a circumferential crack.The solution process is simple,and the closed form solution can usually be found.In practical engineering applications,it gives satisfactory precision.