Study On Fatigue Test Method Of Rubber Bushing Based On Load Spectrum

The rubber bushing is made of rubber material and metal vulcanization.It has been widely used in the automotive suspension system and various kinds of support,because of its advantages such as vibration isolation,noise reduction,absorption of shock,high frequency vibration and manufacturing tolerances.Rubber bushing often works under complex alternating loads in the condition of the vehicle.It is prone to fatigue failure.Because the rubber is a highly nonlinear viscoelastic material,it is difficult to accurately predict the fatigue life through the theoretical method and the finite element analysis.Because of the changing of the structure of the rubber bushing,it is difficult to measure the stress of the rubber in the actual working condition of the vehicle,which makes it difficult to standardize the design of the fatigue test condition.So,it is lack of a complete set of standard test methods for rubber components in our home.In this paper,on the basis of the domestic and foreign development present situation in rubber bushing fatigue life theory,force analysis of big bushing in the front suspension lower arm is carried out.And I establish the mechanical model,bench fatigue test method and fatigue failure criterion.The random road spectrum acquired by vehicle during fatigue test in the fatigue performance test field is pre processed and decomposed.The random spectrum of big bushing is obtained.According to the damage condition of the big bushing,the rain flow counting method and the pseudo damage principle are used to transform the multi-stage load spectrum in bench fatigue test of the rubber bushing,and the test conditions of the bench test are determined.The finite element analysis method can be used to compare the service life of the bushing in road spectrum and test spectrum,and analys feasibility and accuracy.Selecting test sample of big bushing adopts multilevel load spectrum for bench test.This method compares the results of vehicle fatigue test and bench test according to the fatigue failure critetion.This method can be used to verify the feasibility and reliability of road spectrum transformation.The bench test of rubber bushing shows that the pre-pressure,excitation amplitude and excitation frequency in test conditions can be adjusted according to working conditions of the vehicle,which makes the bench test and the vehicle fatigue test have the same damage of bushing.