Thermoplastic Behavior and Application in the Auto Body Light-Weight Manufacture of High Strength Steel

The hot forming process mechanism of high strength steel and its applications in automobile manufacture were comprehensively studied through experimental test, numerical simulation, and theoretical analysis. According to the thermal-mechanical-transformation coupled constitutive model and nonlinear large deformation analysis, a thermoplastic dynamic explicit finite element formulation was established and the sheet metal forming numerical simulation module, king mesh analysis system (KMAS), was compiled and implemented. The use of the KMAS to simulate and analyze the thermoplastic behaviors of high strength steel of the autobody found that the simulated results of the U-shaped blank were in a good agreement with the experimental results; the yield strength and the ultimate tensile strength of final parts were up to about 1 100 MPa and 1 500 MPa, respectively. The use of the KMAS to analyze and compare the vehicle crashing found that compared with the cold formed front bumper, the hot formed one could reduce the weight by 36.5%, while its specific energy absorption could increase by 16.0%.