| The performance of fatigue life is very important for the sheet metal structure in Automotive. The thickness of sheet metal is only 0.6mm ~ 3mm, So the structure of the sheet metal is usually made by punching, drawing or cutting processes. is easily happened for the thin sheet metal structure, shape features and the burr. The stress concentration can easily lead to fatigue cracking. Fatigue cracking usually occurs in the edge portions of the sheet metal part, and the stamping burrs exist in the edge portions of the plate. The stamping burrs can easily cause stress concentration, so it’s easy to reduce fatigue life. In order to further accura tely predict the fatigue life of the sheet metal structure, a new method was proposed to calculate the fatigue life. The effect of stamping burrs was considered when calculated the fatigue life of the sheet metal structure. The method of the numerical simulation was used to simulate the stamping burrs when calculated the stress of the plate, and the quantitative effect of the stamping to fatigue life was calculated. So the accuracy of calculation of the fatigue life was improved.Firstly, the basic principle of numerical simulation for the stamping burrs was proposed. The mechanism of the formation of burrs and the impact of the stamping burrs to structural strength and fatigue life was described. Line spring element was used to simulation the stamping burrs. The constitutive equation of Line spring element was derived. In order to gained the impact of the burrs to stress, the basic principles of the calculation of the element stress was be discussed and the l ine spring element was used to finite element to calculate the element strain, stress and stress concentration factor.Secondly, according to the basic principle of numerical simulation of the stamping burrs, the method of considering the effect of the stamping burrs to analysis fatigue life was proposed. The process to adding element of burrs to finite element model was introduced in detail. According to the calculated stress and the fatigue damage accumulation theory, the fatigue life of the sheet metal structure was analyzed.Finally, to verify the new method, this method was used to the Sliding Door’s Stop Mechanism. The structure of the Sliding Door’s Stop Mechanism was optimized by The Genetic Algorithm and the fatigue life of Stop Mechanism was calculated, under considering of the effect of the stamping burrs to stress. A test bed was established and the experiment was conducted to verify the result of structural optimization and computational fatigue life of the Sliding Door’s Stop Mechanism. There were 4 kinds of parts’ condition: optimal structure with burrs, optimal structure without burrs, original structure with burrs and original structure without burs. According to the result of experiment, it was found tha t the stamping burrs have significant influence to stamping parts. The fatigue life of the optimal structure was increased over 90% than the original structure. After using the method of considering the effect of the stamping burrs to fatigue life, s imulation accuracy of the fatigue life is improved by 44%. |
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