Failure Analysis And Robust Optimization Design Of Typical Compliant Mechanism

In recent years,as compliant mechanisms have been applied to sophisticated areas such as precision measurement,communication,and optics,their demand has gradually increased.In engineering applications,flexible hinges in typical compliant mechanisms are subject to external environmental influences leading to fracture failure,shortening fatigue life,reducing structural reliability,and serious safety issues.In this paper,crack analysis method,finite element method and Paris reverse thrust fatigue method are used to analyze the fracture failure of straight beam type flexible hinge;the stress field strength method and Paris life estimation method are used to form the front and the crack of the straight beam type flexible hinge Fatigue life prediction;using the full factor method and robust optimization design to optimize the parameters of the straight beam type flexible hinge,further optimize its performance,improve the reliability and robustness of the structure,and prevent structural failure.The main research work is as follows:(1)Aiming at the problem that the straight beam type flexible hinge is subjected to alternating stress in engineering application,which leads to fracture failure,a fracture analysis method based on crack analysis method is proposed.Firstly,the finite element method is used to establish the crack model,combined with the Paris inverse stress method and the finite element method,the maximum stress calculation approximate model for the fracture failure of the straight beam type flexible hinge is established.(2)Aiming at the engineering problem that it is difficult to predict the fatigue life of the straight beam type flexible hinge before and after the crack in the compliant mechanism,the stress field strength method and the Paris life estimation method are proposed to predict the fatigue life.Before the crack of the straight beam type flexible hinge,the fatigue life S-N curve is obtained by finite element analysis and simulation,and the mathematical model for calculating the fatigue life is constructed by combining the stress field strength method.After the cracks of the straight beam type flexible hinges,firstly,the crack models with different crack lengths are constructed and the fatigue life SN curves of different crack lengths are obtained by finite element simulation analysis,then the fatigue life of the flexible hinges is established by using the residual life estimation method of Paris model,finally,the linear regression analysis is used to analyze the variance of the fatigue life model before and after the failure of the flexible hinge and the residual analysis to verify the accuracy of the model.(3)Aiming at the problem that the compliant mechanism is affected by many factors in the engineering application,the fracture failure and the reliability and safety of the structure are reduced.The method of optimizing the structural parameters by the full factor method and the robust optimization design method is proposed,the whole factor method is used to obtain the experimental data by creating the experimental design,then,according to ANSYS,the response variable of the experimental design is obtained,and the response variable expansion analysis and the objective function to be optimized are used to establish a response optimization design model,and the response is based on the consensus function method.The problem is regarded as the problem of maximizing the degree of agreement.It is difficult to construct the response optimization design model and the conventional optimization algorithm in the process of structural parameter optimization design.It is difficult to achieve the optimal global parameter problem,and the optimal design scheme under the constraint condition is obtained.The robust optimization design is mainly to further optimize the performance of the structure and improve its reliability and robustness.