多工况应力约束下多用途船货舱结构优化

  目的  为提高有限元结构强度校核效率，减少尺寸优化迭代成本，提出散货船双层底纵桁的板缝布置和尺寸优化方法。  方法  首先，基于理论公式论证子模型技术的可靠性，提出双层底纵桁优化设计的多工况筛选方法。然后，以某散货船双层底纵桁为例，对纵桁进行板格划分，以板格厚度为变量、《散货船和油船共同结构规范》（HCSR）的许用应力为约束条件进行尺寸优化，用穷举法列举所有板缝布置方案对优化后的板格厚度进行合并，选出重量最轻的板缝布置优化方案。最后，基于HCSR舱段有限元计算的屈服强度要求，对上述散货船双层底纵桁需加强的区域进行板缝布置优化，在此基础上，采用尺寸优化方法实现满足屈服强度要求的结构尺寸优化。  结果  结果显示，采用提出的基于尺寸优化的板缝布置优化和结构加强方法能减轻优化区域重量 4.9%。  结论  所提方法能有效减少人为有限元加强时的随机性，优化有限元结构加强方案，减轻结构加强重量。

Optimization of cargo hold structure of a multipurpose ship under multiple load conditions stress constraints

  Objectives  In order to improve the efficiency of structural strength verification in finite element calculation, and reduce workloads for size optimization in iterative process, this paper is intended to propose a method for plate seam arrangement and size optimization of double bottom longitudinal girders of bulk carriers.  Methods  First, based on the theoretical formula, the reliability of the sub-model technology is demonstrated and a multi-condition screening method for the optimization design of double bottom longitudinal girders is proposed. Then, a double bottom longitudinal girder of a real bulk carrier is taken as an example and divided into plate panels. The plate thickness is set as a variable and the permissible stress of the Harmonized Common Structural Rules (HCSR) is used as the optimization constraint in size optimization. The plate seam arrangement with the minimum weight is chosen as the optimized arrangement after using the exhaustive method to list all the seam arrangements and merge the plate thicknesses. Finally, considering the HCSR regulatory requirements about yield strength finite element calculation of hold section, the plate seam arrangement of the longitudinal girder strengthening area of interest is optimized, on this basis, the satisfactory structural sizes that meet the regulatory requirements are obtained using the proposed size optimization method.  Results  The results show that this method for plate seam optimization and structural strengthening based on size optimization can reduce the weight of the optimized area by 4.9%.  Conclusions  The method proposed herein can effectively reduce the randomness of finite element-based manual calculation of structural strengthening, optimize finite element design scheme and reduce the weight of strengthening.