(1. 湖南大学 汽车车身先进设计制造国家重点实验室，长沙 410082；
2. 杭州吉利汽车研究院有限公司 NVH及材料工程部，杭州 311228)
摘 要: 针对汽车用6xxx铝合金薄壁件，采用准静态拉伸实验获得材料的真实应力—应变曲线，通过线性回归拟合的方法得到6061和6063材料的Johnson-Cook本构参数A、B、n值分别为90 MPa、422.58 MPa、0.5234和60 MPa、323.57 MPa、0.428。为了准确地预测铝合金变形过程中的开裂行为，将Crockroft-Latham韧性断裂准则引入到数值模拟中，计算出6061和6063铝合金材料的韧性断裂常数分别为334.09 MPa和309.79 MPa。对铝合金缺口试样拉伸实验和汽车铝合金薄壁件压缩实验进行数值模拟和实验验证，发现试样的力和位移曲线以及断裂位置与仿真预测结果吻合度较高，该方法能够方便、准确地预测两种铝合金材料薄壁件的开裂行为。在实际的工程应用中，该方法成为判断材料的断裂失效的一种有效的方法。
关键字: 铝合金；薄壁件；韧性断裂；数值模拟
（1. State Key Laboratory Design and Manufacture for Vehicle Body, Hunan University, Changsha 410082, China;
2. NVH and Material Engineering Department, Hangzhou Geely Automobile Research Institute Co.Ltd.,
Hangzhou 311228, China）
Abstract:The true stress—strain curve of automobile 6xxx aluminum alloy thin-walled components was obtained by tensile tests. Johnson-Cook constitution parameters of aluminum alloys 6061 and 6063 were analyzed by means of linear regression analysis method, the values of A, B, n of each alloy are 90 MPa, 422.58 MPa, 0.5234 and 60 MPa, 323.57 MPa, 0.428, respectively. In order to estimate the fracture behavior of aluminum alloy during the deformation, Crockroft- Latham ductile damage criterion was incorporated into the numerical simulation. The calculated ductile fracture parameters of 6061 and 6063 aluminum alloys are 334.09 MPa and 309.79 MPa. Simulation approach was employed to predict the fracture of notched sample tensile tests and compression tests of thin-walled aluminum components. The numerical results, such as load-displacement curves and fracture position, are in good agreement with experimental measurements. This method, which provides a valid way to forecast the fracture of material in engineering application, can be used to predict fracture behavior of thin-walled aluminum alloy with satisfactory convenience and accuracy.
Key words: aluminum alloy; thin-walled component; ductile fracture; numerical simulation
