大型机械结构的分层动态优化方法

针对大型机械结构动态优化设计维数高,同时涉及外形尺寸和截面尺寸两类变量,采用整体优化策略,存在收敛困难的问题,提出了采用分层优化结合子结构方法的机械结构动态优化策略。以有限元方法为基础,将外形尺寸和截面尺寸分离到两个相对独立的设计空间,从而将整体优化问题分解为整体层优化和局部层优化两个子优化问题。在整体层以整体结构动态特性最优为目标,完成对外形尺寸的优化;在局部层以子结构动态特性最优为目标,完成对截面尺寸的优化;两层优化交替进行直至问题最后收敛。某型大跨自动扶梯金属结构的动态优化工程实例表明,该方法优化效果良好且优化效率高。

Bi-level Optimization Method for Large-Scale Mechanical Structures

A component dynamic modeling based bi-level optimization strategy,called the global stage and the local stage,is proposed to improve the iteration speed of the dynamic optimization of large-scale mechanical structures.Node information and element information,corresponding to the overall dimension and cross-section size,are isolated into two different design spaces.At the global stage,the nodal positions and the dynamic performance of the overall structure are optimized and the optimized nodal positions are transferred to the local stage.At the local stage the sectional sizes and the dynamic characteristics of the component or substructure are optimized and the optimized sectional sizes are transferred to the global stage.The optimization alternates between the two stages until the final convergence achieved.The component modal synthesis method is employed to determine the objective of the local stage optimization and to measure its effect on the dynamic performance of the overall structure.The dynamic optimization of the mental structure of a practical large-span escalator proves the feasibility and efficiency of the proposed method.