第三代超高强钢QP1180硬化与失效行为研究

Study on Hardening and Failure Behavior of the 3rd Generation Ultra-High Strength Steel QP1180

超高强钢材料是当前汽车上应用最广泛的轻量化材料,精确预测其在整车碰撞过程中的失效风险是目前行业内面临的主要挑战。以第三代超高强钢QP1180为研究对象,采用修正的幂函数硬化模型(MPL模型)来描述变n值类材料的硬化行为,并采用液压胀形方法来验证不同硬化模型外推准确性。设计了5种不同应力状态加载工况,通过DIC测量方法获得了QP1180材料在试验加载工况下断裂极限应变,基于试验数据完成了MMC断裂极限准则参数拟合,通过优化方法完成GISSMO损伤模型参数识别,并进一步设计了帽型梁特征件三点弯曲试验来验证失效特性表征结果。结果表明,MPL硬化模型直接外推预测精度明显优于Swift与H-S模型,更适用于QP1180材料;在复杂非线性应变路径下,GISSMO损伤模型可以较好预测材料的失效行为。

Ultra-high-strength steel(UHSS) are currently the most widely used lightweight materials in automobiles,and failure risk prediction during vehicle collisions is the main challenge currently facing the industry.Modified power law(MPL) hardening model is proposed to describe the hardening behavior of variable n-value materials,and hydraulic bulging test is used to verify the extrapolation results of different hardening models.Five loading case are designed in order to get fracture limit strain under different stress state,and the MMC fracture criterion parameters is fitted based on the experimental data.Optimization method is used to identify parameters of the GISSMO damage model,and the three-point bending test of hat profile is further designed to verify the characterization results of the hardening and failure characteristics.The results show that direct extrapolation result of the MPL hardening model is better than that of the Swift and H-S hardening models,and is more suitable for QP1180 material.The calibrated GISSMO damage model can well predict the failure behavior of the material under complicated nonlinear load path.