基于Lou-2013韧性断裂准则5182铝板成形极限研究

Forming Limit Research of 5182 Aluminum Alloy Sheet Based on Lou-2013 Ductile Fracture Criterion

以Lou-2013韧性断裂准则为理论基础研究5182铝合金板材的韧性断裂力学性能,设计圆孔试件、平面应变试件和平面剪切试件的拉伸试验来获取准则中的材料参数。通过该准则确定'断裂应变?应力三轴度'曲线,为ABAQUS软件中的韧性损伤材料模型提供损伤判据,构建5182铝合金板材的韧性损伤仿真模型。利用此模型对上述三个试件的拉伸过程,以及半球形凸模胀形试验过程进行有限元仿真,并通过数据分析绘制基础拉伸试验与半球形凸模胀形仿真相结合的5182铝合金板材成形极限图。试验与仿真表明,所建立的有限元材料模型能够准确地再现三种试件的力程曲线和断裂特征;通过基础拉伸试验与半球形凸模胀形仿真相结合求解出的成形极限图包含两条曲线:损伤成形极限曲线(Damageforminglimitcurve,Damage FLC)和断裂成形极限曲线(Fracture FLC)。与成形极限试验数据对比表明,采用Damage FLC判定板材破裂失稳偏于安全,为实测成形极限数值的下限,而采用Fracture FLC判定则偏于危险。

Based Lou-2013 ductile fracture criterion,the ductile fracture and mechanical property of 5182 aluminum alloy is studied and the tension tests of hole specimen,plain strain specimen and plain shear specimen are designed to obtain the material parameters in the criterion.The'fracture strain-stress triaxiality'curve is determined by the criterion to provide the critical data of the Ductile Damage Material Model in ABAQUS which offers a simulative way to predicate ductile fracture.Based on the Ductile Damage Material Model,a finite element simulation model is created to predicate the ductile fracture of 5182 aluminum alloy.Utilizing the built model,the tension process of the three specimens is simulated and simultaneously the experimental process of bulging test with a hemisphere punch is also simulated which is used to acquire the simulative forming limit curve(FLC).The result of tension test simulation indicates that the built finite element model could accurately simulate the'force-displacement'curve and the fracture situation of the three specimens.The simulative FLC contains two curves—damage forming limit curve(Damage FLC)and fracture forming limit curve(Fracture FLC).Comparing the simulative FLC with experimental data indicates that Damage FLC is safe while Fracture FLC is dangerous when used to predicate fracture of 5182 aluminum alloy sheet.