DP980钢的动态力学性能及本构模型构建

 随着汽车轻量化事业的不断推进,先进高强DP钢得到了快速的发展和应用。而汽车碰撞过程安全性的模拟仿真,对DP钢提出了动态力学性能数据的迫切需求。利用万能拉伸试验机和高速拉伸试验机系统研究了高强度DP980钢不同应变速率下的力学性能,构建并修正了基于JC模型的动态本构数学模型,并进行了模型计算结果与试验数据的对比分析。试验结果表明,10-4～10-2 s-1的静态应变速率范围内,DP980钢的屈服强度和抗拉强度变化不大,分别在660~675和1 030~1 050 MPa的范围内波动;而均匀伸长率和断裂伸长率则分别为11%和16%。10-1～103 s-1的高应变速率范围内,屈服强度和抗拉强度均随拉伸速率的升高单调增加,应变速率由10-1提高到103 s-1时,屈服强度由690提高到810 MPa,抗拉强度由1 050提高到1 200 MPa;而断裂伸长率呈现先增高后降低的趋势,在500 s-1时达到峰值25%,呈现出明显的应变速率敏感性。基于JC模型修正的动态本构模型,应变速率为101和 102 s-1下的试验结果和模型计算结果具有较高的一致性。动态力学性能数据是影响汽车碰撞过程模拟仿真结果可靠性的关键因素。所研究的实际钢厂DP980钢的动态力学性能演变规律及所构建的动态JC本构模型,可更方便地为汽车厂提供更为准确的力学性能数据支撑,缩短试验时间,降低试验成本,提高汽车碰撞过程模拟仿真结果可靠度。

Dynamic mechanical properties and constitutive model of DP980 steel

With the continuous development of automobile lightweight industry, advanced high strength DP steel has been rapidly developed and applied. The simulation of vehicle collision process safety puts forward an urgent demand for dynamic mechanical property data of DP steel. The tension mechanical properties under different strain rates of DP980 steel were investigated using universal tensile testing machine and high-speed tensile testing machine in this paper. The dynamic constitution mathematical model based on JC model was established. The model calculation results were compared with the experimental data. The results indicate that the yield strength and tension strength are relatively stable under the strain rates of 10-4-10-2 s-1, which fluctuates in the range of 660-675 and 1 030-1 050 MPa respectively, while increases with the increasing of strain rates under the strains rates of 10-1-103 s-1. When the strain rate increases from 10-1 to 103 s-1,the yield strength increases from 690 to 810 MPa,while the tension strength increases from 1 050 to 1 200 MPa. The uniform elongation and breaking elongation are 11% and 16% respectively under the strain rates of 10-4-10-1 s-1. The elongation increases first and then decreases with the increasing of strain rates under high strain rates, and reaches the peak value of 25% under the strain rate of 500 s-1. DP980 steel has obvious strain rate sensitivity. The simulation results under the strain rates of 101 and 102 s-1based on the dynamic constitutive model have great agreement with the experimental results. Dynamic mechanical property data is the key factor affecting the reliability of vehicle collision simulation results. The dynamic mechanical property evolution law of DP980 steel and the corresponding dynamic JC constitutive model studied in this paper can more conveniently provide accurate data support for automobile plants, shorten the experimental time, reduce the experimental cost, and improve the reliability of simulation results of automobile collision process.