Robust And Optimized Design Of Compliance Mechanism Based On Multiple Failure Modes

With the wide application of compliance mechanism in precision engineering,optical engineering,communication engineering and other fields,its reliability requirements are also increasing,as a key part of precision instruments,insufficient reliability will lead to a series of safety problems.In the process of research and application of the structural reliability of the compliance mechanism,there are still some problems: first,the current failure research on the compliance mechanism mainly focuses on fatigue failure,and does not consider other failure modes existing in the compliance mechanism,and the reliability and accuracy results obtained will inevitably be biased and have certain limitations;Second,due to the many design variables of the compliance mechanism,the relationship between the design variables and the response target is difficult to determine.Third,in actual engineering practice,accompanied by many uncertain factors,the fluctuation of these uncertainties will lead to fluctuations in the target performance,and it is impossible to accurately evaluate the reliability of the compliance mechanism.In view of the above problems,this paper uses a micro-displacement amplification mechanism as a typical compliance mechanism as a research carrier,analyzes the reliability of multiple failure modes and designs it robustly,optimizes it,and carries out the following work:(1)Aiming at the problem that the relationship between the design variables and the response target of the compliance mechanism is difficult to determine and only optimize the single response,the experimental data are obtained through orthogonal experimental design and finite element simulation,and the output displacement and natural frequency are converted into signal-to-noise ratio by the Taguchi method,the neural network model is established and the genetic algorithm is used to conduct a global search for the neural network model to quickly find the single-objective optimal solution,and the weight coefficient between the response targets is obtained through the single-objective optimal solution,so as to realize the multi-response robust design of the compliance mechanism.and prepare for subsequent robust optimization designs for multiple failure mode reliability.(2)Aiming at the problem that the compliance mechanism mainly focuses on optimizing a single fatigue failure in the failure mode,the reliability analysis of the correlation of multiple failure modes is carried out on the compliance mechanism,and the reliability analysis model of multiple failure modes is established on the basis of extracting the key structural parameters of the micro-motion amplification mechanism.The failure mode correlation coefficient matrix is obtained,and the introduction of the correlation coefficient matrix allows the system reliability to fully consider the degree of correlation between failure modes.The reliability analysis and sensitivity analysis of multiple failure modes are carried out,and the importance ranking of each random variable is given,which is conducive to determining the targeted method for reliability optimization of the compliance mechanism.The accuracy of the method is demonstrated by comparing the experimental results with Monte Carlo method and without considering the correlation of failure modes.(3)Aiming at the low reliability of the system and the easy fluctuation of uncertain factors,the reliability optimization design of multiple failure modes of the compliance mechanism is carried out.The reliability robust optimization model of the compliance mechanism is constructed,and the conversion relationship between it and the reliability optimization model constrained by reliability index and the reliability optimization model constrained by probability function measure is given,and an improvement method is proposed.Taking the reliability of multiple failure modes as constraints,the displacement amplification ratio and natural frequency of the compliance mechanism as the objective function,and introducing sensitivity additions,the performance and overall reliability of the compliance mechanism are effectively improved under the reliability requirements of each failure mode,and the resistance of the compliance mechanism to the influence of variable fluctuations is improved,so that the robustness of the compliance mechanism is further improved.