The Optimization And Engineering Application Of 6σ Robust Based On Uncertain Design Parameter

In the practical engineering application,it has become a hot topic in the robust optimization design method which effectively reducing the impact of uncertain factors on the products quality.As the uncertain problem become more and more complex in product development,design,manufacture and maintenance.The existing robust optimization design method has been difficult to adapt to various uncertain engineering problems.It’s important meaning to improve products quality stability by robust optimization design method with considering uncertainty and assist design engineer to choose reliable design scheme.This paper aim at the practical engineering demand of the compliant mechanism products in the highly sophisticated field.So base on the uncertainty case,the 6σ robust optimization design method is proposed to effectively solve the compliant micro-manipulation quality fluctuation problem.The main content of this paper include the following aspects:(1)With the problem to screen suitable uncertain structural design variables for compliant micro-manipulation stage,the Plackett-Burman experiment for this engineering problems is adopted.At first,this paper arranged and classified the influence of stage quality fluctuation of uncertain factors by fishbone diagram method.It provides the screening process by the Plackett-Burman experiment design method based on the analysis problem of practical engineering application.Then the Plackett-Burman experiment design method is used to select the significant uncertain design variables.The method can reduce the model calculation and improve the accuracy of the surrogate model.As the same to reduce the model computational complexity and the number of iterations.It lays the groundwork for high efficiency robust design.(2)In most of practical engineering optimal problems,the complex implicit nonlinear relationships between target response and uncertain design variables are unknown or complicated.So a response surface surrogate model method is adopted to solve this problem in robust design.Firstly,significance uncertain design variables of experiment combination are rearranged by the central composite design method.Secondly,constructed response surface surrogate model of natural frequency and displacement magnification by finite element numerical simulation experiment combination data.Finally,the surrogate model precision has been evaluated for preparing establish 6σ robust optimization model with compliant micro-manipulation stage.This method reduces greatly the size of search space,the computational complex and the number of iterations.It’s lays the foundation for quickly and effectively to obtain robust design.(3)The traditional deterministic optimal design model is not considered design variables’ uncertainty.In view of the situation,a 6σ robust optimization model based on uncertain design variables is given.Firstly,this paper analyze disadvantages of the traditional deterministic optimization method about solve the uncertainty problem.The process of 6σ robust design optimization model is built.As to compliant platform in the research,then it summarized the 6σ robust optimization model build process.And on this basis establishing structural parameter 6σ robust optimization design model,the sensitivity method used to estimated responses’ mean and variance of variables.Finally,NSGA-II algorithm is used to optimize target responses.The results of new method compared with the results of traditional optimal design model.It shows that new method has effectiveness for the uncertain problems in compliant mechanism.