Lightweight design of car body mechanism based on fatigue life

In order to reduce the fatigue life of the car body caused by the dead weight of the car body, a lightweight design of the car body mechanism based on the fatigue life is proposed. The modal analysis of the car body is carried out by establishing the finite element model of the car body. According to the generated modal neutral file, a rigid-flexible coupling multi-body dynamic model is established, which enables the comprehensive and in-depth analysis of the fatigue life of the car body. According to the analysis results, the topological optimization theory is adopted, and the constraint conditions are established based on the static stiffness characteristics of the car body. Specific design schemes are put forward from two aspects of bending stiffness and torsional stiffness, and these two variables are limited to obtain the optimal value of the car body structure and realize the lightweight of the car body. The test results show that the proposed method can reduce the weight of car body structure, and the variation range of torsional stiffness and bending stiffness is within 5%, which can improve the fatigue life of car body. It shows that the proposed method has certain reference value for lightweight design of side body.