The Research On The Dynamic Strength Reliability And Its Sensitivity Of The Planar Linkage Mechanism

With the development of science and technology, the material used on mechanisms becomes lighter and the operating speed of mechanism gets faster. This makes the reliability of the mechanisms attract more and more people’s attention. Thus, an effective method is needed to study the reliability of mechanisms, to find the sensitive factors that affect the reliability of mechanisms and to do some improvements accordingly.By means of scientific computing software MATLAB, this paper analyzed the strength reliabilities and sensitivities of slider-crank mechanism with rigid and flexible connecting rod respectively. Meanwhile, on the basis of the analysis, the reliability optimization and robustness design were done. The content is as follows:(1)Under the assumptions of rigid crank and connecting rod, with the basic rod group splitting method, the movement and force of the basic rod group were first analyzed. Based on the above analysis result, the second order moment mean value method, the optimized second order moment method and Monte Carlo method were adopted to calculate the dynamic strength reliability and sensitivity of the rod parts and the whole system. The accuracy of the calculation is verified by these three calculation methods.(2)Supposing the connecting rod is flexible and the crank is rigid, the dynamic model of the entire slider-crank mechanism was created with the modal synthesis method, and 4 order implicit Runge-Kutta method was used for its solution. By means of BP neural network technology, the dynamic strength reliability performance function was construct, and the second order moment mean value method, the optimized second order moment method and Monte Carlo method were adopted to calculate and analyze the reliability and sensitivity at the most dangerous time.(3) The reliability optimization and robust design were applied to the rigid slider-crank mechanism. In the whole process, the minimum reliability should be set as the constraint conditions; With weight processing method, the function with multiple targets was transformed into the one with single target, and the random variable which affected the dynamic strength reliability was optimized, and the optimal point was obtained through optimization. With the obtained optimal design point, the reliability and sensitivity analysis were carried out again, and then the comparison was made with the unoptimized results.From the analysis of this paper, the most unreliable position in the process of working can be obtained, as well as the sensitive factors that can influence the reliability of mechanisms. The results obtained by optimizing the can be of significant help to the organization’s actual design, manufacturing and practical use.