Simulation, experiment and application of the damage analysis in the sheet plate forming based on modified Lemaitre model

Abstract

In this study, the accuracy of the test and simulation was verified and applied to the process of forming lightweight components of automobiles. First, the cupping test of 5052 aluminum alloy was carried and the reliability of the modified Lemaitre damage model was further analyzed by numerical simulation. The reliability of the corrected Lemaitre damage model is verified by comparing the Erichsen cupping index (IE), stress-strain damage distribution and the relative position of macroscopic cracks between the test and the simulated IE, and the fracture morphology of the cupping test under different loading speeds is analyzed by scanning electron microscopy (SEM), the results show that during the numerical simulation of the cupping protrusion of the aluminum alloy sheet, the maximum equivalent stress and equivalent plastic strain of the sheet metal appear near the contact area between the sheet and the top of the punch, which is distributed in a circular shape, and the shape of the specimen fracture simulated by the modified Lemaitre damage model is close to the shape of the test fracture, which belongs to the dimple-shaped fracture, and the large and deep dimples are distributed in the middle of the dense small dimples, showing the characteristics of ductile fracture. The IE value predicted by the simulation is small, and the error of the test is small. Then, the modified Lemaitre model was applied to the process of forming the automobile engine cover plate to predict its rupture position.