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    B1500HS热成型钢焊点失效行为的数值模拟

    Numerical Simulation of Failure Behavior of B1500HS Hot-Stamped Steel Spot Weld

    • 摘要: 对B1500HS热成型钢进行电阻点焊试验,设计涵盖拉伸、剪切、弯曲、扭转及其耦合工况的试验矩阵并进行焊点失效试验,研究了不同工况下的焊点失效行为;建立了同时考虑焊核与热影响区失效的焊点分区有限元模型,提出了描述焊核失效面的耦合损伤失效本构模型,通过试验结果与模拟结果对标,确定了模型参数并验证了模型模拟焊点失效行为的准确性。结果表明:B1500HS热成型钢焊点在试验矩阵工况下呈现焊核失效与热影响区失效2种失效模式。所建模型在试验矩阵工况下模拟得到的焊点失效位置与试验结果一致,峰值载荷、断裂位移与试验结果的平均相对误差分别为4.0%和5.0%,满足整车碰撞仿真精度需求(小于15%),说明提出的焊点分区建模方法与焊核耦合损伤失效本构模型能够有效预测B1500HS热成型钢焊点碰撞失效过程中的力学行为。

       

      Abstract: Resistance spot welding tests were conducted on B1500HS hot-stamped steel. A test matrix encompassing tensile, shear, bending, torsional, and coupled loading conditions was designed, and failure tests of the spot welds were performed. The failure behaviors of spot welds was studied under different loading conditions. A partitioned finite element model of the spot welds was established, which simultaneously considered the failure of both the weld nugget and the heat-affected zone. A coupled damage-failure constitutive model was proposed to describe the failure surface of the weld nugget. The model parameters were determined and the accuracy of the model in simulating spot weld failure behavior was verified through the correlation of test and simulation results. The results show that the B1500HS hot-stamped steel spot welds exhibited two failure modes under the test matrix conditions, including the weld nugget failure and the heat-affected zone failure. The failure locations of the spot welds simulated by the established model under the test matrix conditions were consistent with the test results. The average relative errors for the peak load and fracture displacement between the simulation and test results were 4.0% and 5.0%, respectively, meeting the accuracy requirement for full-vehicle crash simulation (less than 15%). This demonstrated that the proposed partitioned modeling approach for spot welds and the coupled damage-failure constitutive model for the weld nugget could effectively predict the mechanical behavior of B1500HS hot-stamped steel spot welds during crash failure processes.

       

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