Fatigue Damage Analysis Of Pickup Truck Leaf Springs Based On Road Load Spectrum Of The Proving Ground

Leaf spring is a kind of elastic element widely used in automobiles,and its fatigue life is very important to the driving safety and reliability of the whole vehicle.Currently,researchers mainly study the fatigue life of leaf springs through national standard bench test and enhanced road test in the proving grounds.Few scholars have adopted the method of combining enhanced road vehicle test and CAE simulation to determine the fatigue life of leaf springs,and the difference and relevance of fatigue life results under national standard test and proving ground conditions are rarely concerned.Under this circumstance,this paper takes the leaf spring of a certain type of pickup truck as the research object,and analyzes the fatigue life of the leaf spring under the test field strengthened road and under the national standard bench test.According to the enhanced road acquisition specifications in the proving ground,the distribution of vehicle sensors and the signal acquisition plan are formulated,and the enhanced road signal acquisition test of a pickup truck of a proving ground is carried out.The original test signals are obtained and the data validity analysis and signal preprocessing are carried out.Reorganize the working conditions of the load spectrum to provide basic data for the subsequent fatigue damage analysis of the leaf spring.The finite element model of the leaf spring is constructed.Three modeling methods including the discrete beam method,the medium plane method and the flexible body method are selected to create the leaf spring multi-body dynamic model,and the leaf spring stiffness characteristic test is carried out to verify the accuracy of the leaf spring finite element model and the multi-body dynamics model;the multi-body dynamics model of the whole vehicle containing different leaf spring multi-body models is built,and the suspension K&C characteristic test and simulation are carried out to verify the accuracy of the whole vehicle model.Three multi-body models of leaf springs are used for virtual iteration.The simulation data of monitoring points are obtained and compared with the test signals.It is shown that the simulation data obtained by virtual iteration of the discrete model and the medium plane model can meet the accuracy requirements,while the flexible body model does not suitable for virtual iteration.Comparing the time-domain curve and pseudo-damage of the load spectrum obtained by virtual iteration using the discrete model and the medium plane model shows that the value of the load spectrum extracted by the medium plane model is slightly larger than that of the discrete beam model,but comprehensively considers the difficulty of modeling and the efficiency of simulation and other factors,this paper finally chooses to use the discrete beam model for virtual iteration,and uses the load spectrum extracted by virtual iteration using this model to carry out the fatigue life analysis of the leaf springBased on the nominal stress approach,the fatigue damage of the leaf spring under the fatigue endurance test of the test field and the national standard bench test is obtained,and the two damage results are compared.The results show that the fatigue damage of the leaf spring under the enhanced road conditions in the proving ground is greater than the fatigue damage of the leaf spring under the national standard bench conditions,and the maximum damage occurs at different locations.Therefore,the fatigue damage of the leaf spring should be predicted based on the fatigue durability test standard in the proving ground.The correlation coefficient of leaf spring damage is defined,in order to use the fatigue damage simulated by the national standard bench test to be equivalent to the fatigue damage under the test field strengthening road conditions,and provide reference value for researchers to predict the leaf spring fatigue in the early stage of leaf spring design.