基于可靠性的弹性折叠机构设计优化方法研究

描述了基于可靠性的弹性折叠机构设计优化方法。采用特征造型方法建立了弹性折叠机构几何模型,CAD二次开发技术实现了折叠机构模型的参数化自动建模;考虑折叠机构几何参数不确定性,建立了折叠机构可靠性动态分析模型;基于功能函数的极小变换法将机构动态可靠性分析问题简化为静态问题;采用一次二阶矩法分析了机构折叠时间、最大应力和机构寿命的可靠度;以折叠机构几何参数为设计变量,采用修正的可行方向法驱动优化使折叠机构质量最轻且寿命更长。数值分析结果显示功能函数的极小变换法将机构动态可靠性分析简化为静态可靠性分析,可以在保证分析精度的前提下,提高可靠性分析效率;同时与传统优化方法比较表明,可靠性优化设计方法可以通过牺牲部分优化目标性能换取优化设计结果可靠性的提高。

Reliability based design optimization method of compliant folding mechanisms

This paper describes a design optimization method of compliant folding mechanisms based on reliability analysis. The folding mechanism model is given by the feature based parametric design method based on the CAD secondary development technology. The dynamic reliability model is given by considering the uncertainty of geometry parameters of the folding mechanism. Based on the minimum transform method, the dynamic reliability analysis problem is simplified to the static reliability analysis problem. The reliability analysis of the folding time, maximum stress and mechanism life is made by the first order reliability method. The geometry parameters taken as design variables are used to minimize the mechanism mass and maximize the mechanism life, and the modified method of feasible directions is used to search the optimum design of the folding mechanism. The numerical results show that the minimumtransform method can improve the reliability analysis efficient and ensure the analysis accuracy. Furthermore, comparisons with the traditional optimization method show that the reliability analysis method can significantly improve the reliability of the optimum design by reducing the performances of optimization objectives slightly.