一种基于DF系列改进的金属薄板韧性断裂准则

An improved ductile fracture criterion for metal sheet based on DF series

为了精确地描述延性金属在不同应力状态下的断裂行为,通过对材料塑性变形时内部微观孔洞的形核、生长和聚合机制的分析,提出了一种改进的基于DF系列的韧性断裂准则,该准则充分考虑了孔洞颈缩合并机制对材料韧性断裂行为的影响,明确了准则中各参数的物理意义。利用此韧性断裂准则构建了AA 2024-T351铝合金和AISI 1045碳钢的等效断裂应变包络面,并将相应应力状态下的断裂应变预测值与此前学者们的试验结果进行了对比,验证了所提出的新准则的有效性。最后,将预测结果与广泛使用的DF2016准则、 Hu准则和穆磊准则的预测结果进行比较,结果表明,相较于其他3种模型,提出的新准则的平均预测误差与最大预测误差最小,预测精度最高,孔洞颈缩合并机制在延性金属断裂过程中发挥了重要作用,应当充分考虑。

To accurately describe the fracture behavior of ductile metal under different stress states,an improved ductile fracture criterion based on the DF series was proposed by analyzing the mechanism of nucleation,growth and polymerization of internal micro-voids for materials during plastic deformation,which fully considered the influence of void necking coalescence mechanism on the ductile fracture behavior of material,and the physical meaning of each parameter was clarified.Then,the equivalent fracture strain envelope surfaces of AA 2024-T351aluminum alloy and AISI 1045 carbon steel were constructed by the proposed ductile fracture criterion,and the predicted fracture strain values under corresponding stress states were compared with the experimental results of previous scholars to verify the effectiveness of the proposed new criterion.Finally,the predicted results are compared with those of the widely used DF2016,Hu and Mu Lei criteria.The results show that compared with the other three kinds of models,the proposed new criterion has the lowest average prediction error and the maximum prediction error,and the prediction accuracy is highest.Thus,the mechanism of void necking coalescence plays an important role in fracture process of ductile metal and should be fully considered.