Study On Durability Of Vehicle Body Based On Dynamic Load

Durability is the most basic and important index of automobile durability,safety and NVH.It is one of the signs of automobile quality.It is also an important content of automobile performance development.Vehicle body is an important subsystem of the whole vehicle.As a focus of vehicle research,vehicle durability has been widely concerned by the industry.The complexity of body structure and its actual load conditions brings challenges to predict body fatigue quickly and effectively.As the key bearing structure of vehicle,the durability of vehicle body is an important index to ensure the reliability and durability of vehicle.There are three main factors affecting the durability of the body structure.The first caused by the amplitude of the load,which directly affects the stress at the loading point.The second caused by the phase of the load,which leads to torsional bending of the body.The third caused by the frequency of the load.When the natural frequency of the body structure is close to the frequency of the external load,the product will be produced Vibrational fatigue.In the durability analysis of automobile body structure,the main method to obtain the stress change is static linear stress superposition,get the stress change,and then carry out fatigue analysis.Fatigue analysis based on static linear stress superposition method can not predict the vibration response of the body itself.When the natural frequency of the body structure is close to the external load frequency,vibration fatigue will occur.The design of body structure by static strength method tends to make the structure tend to infinite life,and the safety factor is too large,which is not conducive to the lightweight of vehicles.In this paper a SUV car was selected to build a body model.Then the dynamic stress was be calculated by using the dynamic load analysis of the body joints,and the stress changes are obtained by using the static superposition method and the modal superposition method respectively.Then the fatigue life of the weak area of the body structure was be predicted by using the stress change process,and the fatigue life is predicted in the design.Risk structure was be optimized.