Fatigue Life Analysis And Program Load Spectrum Compilation Of Forklift Truck Frame Based On Virtual Iteration

With the rapid development of logistics and transportation,forklift trucks are playing an increasingly important role in all kinds of goods transportation.Forklift truck has both driving conditions and operating conditions.The frame needs to undertake both the random load caused by road excitation and the load transmitted by the door frame during operation.The fatigue and durability of forklift truck frame assembly is faced with great challenge because of its complex force.Aiming at the durability problem of a forklift truck in the process of product development and trial production,a method of fatigue life analysis and evaluation for the forklift truck frame is proposed in this paper.The acceleration signal on the frame of the forklift was measured and used as the target signal during load iteration in the vehicle test ground.The dynamic model of the entire forklift truck is established,and the complex load excitation effect transmitted to the frame is confirmed by the virtual iteration method,and the load spectrum borne by the frame is obtained.Based on the finite element model of the forklift frame structure,the load spectrum obtained by virtual iteration and the related material characteristic curves in LMS.Virtual.Lab,the fatigue damage of the forklift frame under different cyclic conditions was analyzed.The fatigue life results and the stress time history of the dangerous points were obtained.Based on the stress spectrum of the danger point in the fatigue life analysis of forklift truck,a set of programming load spectrum for accelerated life test of forklift truck frame is proposed.The stress spectrum of the dangerous point was counted by rain flow,and the statistical distribution characteristics of load amplitude and mean value were analyzed and evaluated.The probability density function of load mean value was estimated by non-parametric kernel density estimation method.Then,according to the Conover method,the two-dimensional load spectrum of the stress at the dangerous point of the forklift frame is compiled,and the one-dimensional load spectrum is further compiled.Then,the virtual test bench was designed and built.According to the relationship between the load of the virtual test bench and the stress of the fatigue damage danger point of the frame,the stress load spectrum was transformed into the program load spectrum of the virtual test bench.Compared with the fatigue simulation results of the road test load spectrum,the position of danger points and the size of damage generated by the load spectrum simulation of the accelerated life test program compiled are consistent with the road spectrum,and the test time is effectively shortened.The research results in this paper provide reference for forklift truck frame load spectrum collection,fatigue analysis and accelerated life test design.