高强度钢板热塑性行为及在车身轻量化中的应用

为深入研究板材热塑性变形机理以及促进热成形工艺在汽车结构件生产制造中的应用,采用理论、试验与仿真相结合的方式,基于高强度钢板热-力-相变耦合本构关系,结合弹塑性非线性大变形分析建立了热塑性成形动力显式有限元列式,开发了高强度钢板热成形数值仿真有限元分析软件,对一款U型试件的热成形过程进行数值模拟,模拟结果与试验一致,且通过拉伸试验获得了成形后零件的力学性能,屈服极限在1 100 MPa以上,强度极限可达1 500 MPa以上. 并通过数值仿真对比一款热成形前保险杠与原始冷成形保险杠的碰撞过程,得出保险杠采用热成形件可减重36.5%,比吸能比原始模型增加16.0%.

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%.