(西北工業(yè)大學(xué) 航空學(xué)院，西安 710072)
摘 要: 通過將改進(jìn)的X-W延性金屬斷裂模型結(jié)合修正的von-Mises準(zhǔn)則嵌入ABAQUS/explicit用戶材料子程序VUMAT的方式，對(duì)一系列鋁合金2A12-T4試件的漸進(jìn)斷裂過程進(jìn)行數(shù)值模擬，該模型以連續(xù)損傷力學(xué)為基礎(chǔ)，并考慮靜水壓力和Lode角對(duì)損傷變量的作用。為了預(yù)測(cè)該模型的有效性并預(yù)測(cè)金屬的延性斷裂，對(duì)鋁合金2A12-T4光滑圓棒、帶缺口的棒材和緊湊拉伸試件(CT試件)進(jìn)行單向拉伸試驗(yàn)及數(shù)值模擬。同時(shí)對(duì)比分析幾何非線性和屈服準(zhǔn)則的影響在數(shù)值仿真計(jì)算中的差異。結(jié)果表明，該斷裂模型結(jié)合修正的von-Mises屈服準(zhǔn)則可很好地預(yù)測(cè)2A12-T4試件漸進(jìn)破壞試驗(yàn)的載荷-位移曲線及各試件的宏觀斷裂形貌。其中，“隧道”效應(yīng)能夠很好地解釋CT試件處于平面應(yīng)變狀態(tài)的中心層和平面應(yīng)力狀態(tài)的表面層的抗斷裂能力的差異。
關(guān)鍵字: 鋁合金；緊湊拉伸試件；斷裂；幾何非線性；有限變形
（School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072, China）
Abstract:A modified X-W ductile fracture model with modified von-Mises yield criterion based on the continuum damage mechanics which combined the effect of pressure and Lode angle on damage variable was implemented into ABAQUS/explicit through the user subroutine VUMAT to simulate the progressive failure of specimens of aluminum alloy 2A12-T4. In order to verify the modified fracture model and predict the progressive failure behavior of the ductile metals, a series of experiments of aluminum alloy 2A12-T4 specimens including smooth and notched round bars and compact tension (CT) specimen as well as corresponding numerical performances were conducted. Meanwhile, different numerical simulations with or without geometric non-linearity and different yield criteria were studied by comparing the difference. The numerical results show that the fracture model with modified von-Mises yield criterion can accurately and effectively predict the experimental results of 2A12-T4 specimens including load-displacement curves and macroscopic fracture morphology. Among them, the “tunnel” effect appearing in CT specimen can directly explain the difference of the fracture resistance between in plane stress layer and in plane strain layer.
Key words: aluminum alloy; compact tension specimen; fracture; geometric non-linearity; finite deformation
