含点蚀损伤7075-T6铝合金拉伸性能数值模拟

NUMERICAL SIMULATION OF THE TENSILE BEHAVIOR OF Al 7075-T6 ALLOY WITH CORROSION PITS

在环境腐蚀的作用下,高强度铝合金的宏观拉伸性能,尤其是断裂延性会出现明显下降,严重危害结构的安全。文中在细观力学分析的基础上,引入细观损伤变量——孔隙率等效点蚀坑对材料性能的影响。根据未腐蚀材料拉伸试验数据,回归给出改进的孔隙率演化模型中的参数值。使用改进的Gurson屈服准则,对经过不同时间预腐蚀的7075-T6铝合金的延性断裂性能进行数值模拟。数值结果与试验结果吻合,证明文中方法的正确性和有效性。

Corrosion which occurs at local scale has been found to result in a dramatic macroscopic tensile ductility loss of the 7075 Aluminum alloy. The aim of the present paper is to investigate the plastic property and ultinmate strength characteristics of high strength Aluminum alloy with corrosion pits. The tensile behavior of corroded 7075-T6 specimens has been simulated on the basis of mieromechanics analysis by taking into account the degree of corrosion pit by weight loss rate. The mathematic description of the void volume fraction evolution is modified and the parameters in the modified model were obtained according to the tensile test results of uncorroded material. Ductile fracture behavior of the specimens with different corrosion time was analyzed by using the modified Gurson model. The results of numerical simulation agree well with experimental data. The insights developed from the present study will be very useful for damage tolerant desian of Aluminum allov structures with Pit COrrosion damage.