Frequency Reliability Analysis And Optimization Of Connecting Rod Of A Single Cylinder Engine

Connecting rod is one of the key components in the motion mechanism.During the working process of the engine,the connecting rod is affected by various complex periodic changes of load,thermal stress and vibration.These effects make the connecting rod fail to work during the process.The engine will also fail to work because of the failure of the connecting rod.Therefore,it is very important to conduct the reliability analysis and optimization of the connecting rod components on the basis of the dynamic analysis of the crank and connecting rod mechanism.This article combines system dynamics,finite element analysis,reliability theory and other related basic theory disciplines.The finite element analysis software,multi-platform integrated optimization design software and MATLAB software are used to conduct the Dynamic analysis,Finite element analysis and Modal analysis of single cylinder engine connecting rod of ZongShen NC450 Engine.An integrated interactive simulation experiment is designed to obtain the modal frequency response under the input of random design variables.While the Frequency Reliability Analysis and Optimization of Connecting rod is also completed,and the method of frequency reliability analysis and optimization is summarized.The specific research contents of this paper are as follows:(1)According to the motion model and mechanics model,the kinematics and dynamics knowledge are used to get the parameter change diagram of the related components during the working process of crank and connecting rod mechanism by MATLAB.The force curve of the the big head and the small head of the connecting rod and the displacement and load constraint of the finite element analysis of the connecting rod are determined.(2)The finite element analysis model of connecting rod is established by using ANSYS software.Through the static strength analysis of the connecting rod,the stress cloud under the maximum tensile and compressive working conditions is obtained.The dangerous nodes with stress concentration in the working process are determined,and the stress extreme value under two working conditions is also obtained.Then,the static strength check of the connecting rod is completed.(3)Using ANSYS software,the analysis of the restraint mode of the connecting rod is completed.The simulation experiment is designed by multi platform integrated optimization software ISIGHT and ANSYS.The response value of the lowest ordernatural frequency of the connecting rod under random design variables input are solved.In the design of DOE experiment,the main effect analysis and Pareto diagram analysis are carried out on the sample pairs,and the design variables which are more sensitive to the response are selected.(4)MATLAB is used to compile the BP neural network program,and the nonlinear neural network regression analysis is carried out for the selected samples.According to the weights and thresholds satisfying the design accuracy,the frequency performance function of the connecting rod is fitted.With First-order second moment method,the frequency reliability of the connecting rod is analyzed.(5)Taking the reliability and the lowest natural frequency as the target,the idea of the RBF neural network surrogate model ASA algorithm(adaptive simulated annealing algorithm)are applied to optimize the reliability and design variables of the connecting rod.After optimization,the lowest frequency of the connecting rod is increased by32.6%,which reduces the possibility of the connecting rod falling into the resonance frequency area when working,and the corresponding reliability index has increased by5.2%.