铝合金在两种应力状态下损伤的有限元模拟

通过对铝合金（6063）进行缺口拉伸及纯剪切试验，研究了铝合金在这两种应力状态下的损伤没断裂机制。研究结果表明：缺口拉伸试验中，缺口根部产生相对较高的三轴应力，随着应力的不断升高，微孔洞的体积分数不断增大。当达到材料的临界孔洞体积分数时，试样断裂；纯剪切试验中，在材料内部几乎没有产生微孔洞而产生了剪切带。显微裂纹首先在剪切带中产生，随着裂纹的进一步扩展，最终导致试样断裂；用改进的Gurson模型和Johnson-cook模型分别模拟缺口拉伸和纯剪切试验，横拟的工程应力-应变曲城与试验的工程应力，应变曲线符台得很好。另外根据有限元模拟和试验数据还得出了6063（T6）铝合金缺口试样中微孔洞损伤的经验演化方程。

FEM Simulation of Aluminum Alloy Damage under Two Kinds of Stress State

The fracture mechanism and damage mechanism of aluminum alloy(6063) were investigated by notched tensile test and pure shear test.The results of study is as follows: During the tensile test,the notch root produces relative high triaxial stress state.With the constant increasing of the stress,the volume of the microvoid in notch root is increasing constantly.When it reaches the critical micro-void volume fraction,the specimen fractures;during the pure shear test,there is almost no microvoid but shear band within the specimen.The cracks are firstly produced in the shear band and then result in specimen fracture with the microcracks extension and coalescence.The modified Gurson model and Johnson-cook model were used to simulate the notch tensile and shear tests respectively,simulation engineering stress-strain curve fit measured engineering stress-strain curve very well.In addition,the empirical damage evolution in the notch specimen was obtained from the experimental data and FEM simulations.