(1. 湖南大學(xué) 汽車車身先進設(shè)計制造國家重點實驗室，長沙 410082；
2. 杭州吉利汽車研究院有限公司 NVH及材料工程部，杭州 311228)
摘 要: 針對汽車用6xxx鋁合金薄壁件，采用準(zhǔn)靜態(tài)拉伸實驗獲得材料的真實應(yīng)力—應(yīng)變曲線，通過線性回歸擬合的方法得到6061和6063材料的Johnson-Cook本構(gòu)參數(shù)A、B、n值分別為90 MPa、422.58 MPa、0.5234和60 MPa、323.57 MPa、0.428。為了準(zhǔn)確地預(yù)測鋁合金變形過程中的開裂行為，將Crockroft-Latham韌性斷裂準(zhǔn)則引入到數(shù)值模擬中，計算出6061和6063鋁合金材料的韌性斷裂常數(shù)分別為334.09 MPa和309.79 MPa。對鋁合金缺口試樣拉伸實驗和汽車鋁合金薄壁件壓縮實驗進行數(shù)值模擬和實驗驗證，發(fā)現(xiàn)試樣的力和位移曲線以及斷裂位置與仿真預(yù)測結(jié)果吻合度較高，該方法能夠方便、準(zhǔn)確地預(yù)測兩種鋁合金材料薄壁件的開裂行為。在實際的工程應(yīng)用中，該方法成為判斷材料的斷裂失效的一種有效的方法。
關(guān)鍵字: 鋁合金；薄壁件；韌性斷裂；數(shù)值模擬
（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
