基于模拟植物生长算法的自由曲面空间网格结构形状优化方法

Shape optimization method of free-form space grid structures based on plant growth simulation algorithm

针对自由曲面空间网格结构形状优化问题,将模拟植物生长算法(PGSA)引入结构形状优化领域。根据PGSA基本原理,提出双生长点并行生长机制、迭代稳定性判断机制及增强型随机多向搜索机制,并和基于生长空间限定与并行搜索算法(GSL&PS-PGSA)相结合,建立了基于融合GSL&PS-PGSA的自由曲面空间网格结构形状优化方法。该方法以广义形状参数表征形状优化设计变量,可有效避免产生奇异结构并提高优化效率。在此基础上,给出了相应的形状优化模型及流程,并采用MATLAB及ANSYS二次开发语言APDL编制了优化程序。对典型合理拱结构曲面及自由曲面网壳结构进行算例分析,结果表明:所提出的PGSA新机制显著提升了算法的寻优能力及稳定性;基于融合GSL&PS-PGSA的自由曲面空间网格结构形状优化方法,其优化效果明显,发掘了结构的合理形态,改善了结构的受力性能,适用于多变量、多荷载组合及复杂约束的大规模自由曲面空间网格结构形状优化,为复杂形体空间结构的设计选型提供了新的途径。

Aimed at the structural shape optimization of free-form space grid structures,the plant growth simulation algorithm(PGSA)is introduced to the field of structural shape optimization.Based on the basic principle of PGSA,the parallel growth mechanism of double growth points,the iterative stability judgment mechanism and the enhanced random multidirectional search mechanism are proposed.Then,combined with the so-called GSL&PS-PGSA algorithm(based on growth space limitation(GSL)and parallel search(PS)),a novel shape optimization method of space grid structures based on the integrated GSL&PS-PGSA is established.The generalized shape parameters are used to characterize the design variables for shape optimization,which can effectively avoid the generation of singular structures and improve the optimization efficiency.On this basis,the corresponding structural optimization model and process are given,and the optimization programs are compiled by MATLAB and the secondary development language APDL of ANSYS.The shape optimization of typical camber arch and free-form latticed shells are analyzed by the proposed method.The results show that the new PGSA mechanisms can significantly improve the searching ability and stability of the algorithm.In addition,the shape optimization method of free-form space grid structures based on the integrated GSL&PS-PGSA has obvious optimization effects.It can effectively explore rational structure forms and improve mechanical performance of the structure.The proposed shape optimization method can be applied to the shape optimization problems of large-scale free-form space grid structures with multiple variables,multiple load combinations and complex constraints,and provides a new approach for the design and form selection of complex space structures.