7075-T651铝合金靶板剪切冲塞的试验和数值模拟研究

为揭示在断裂准则中引入Lode角的必要性，在一级轻气炮上开展了刚性平头弹侵彻7075-T651铝合金靶板试验,获得了靶板的断裂行为和弹道极限；通过圆棒试样拉伸试验和平板试样剪切试验，标定了Johnson-Cook(JC)本构模型和断裂准则参数和一种Lode角相关的断裂准则；运用ABAQUS软件，分别采用Lode角相关和无关断裂准则对试验进行了三维数值模拟,并对Lode角的影响进行了分析。结果表明：在刚性平头弹撞击下，7075-T651铝合金靶板发生剪切冲塞破坏；7075-T651铝合金的断裂与Lode参数相关，剪切带中初始失效材料的应力三轴度低于0且Lode角接近0，用圆棒拉伸试验标定的JC断裂准则高估了断裂应变；采用JC断裂准则预报的断裂行为与试验有较大差别，得到的弹道极限比试验值高大约42%；采用Lode角相关断裂准则得到的弹道极限与试验结果吻合较好。
Abstract：To reveal the necessity to introduce Lode angle into a fracture criterion, tests on a one-stage light gas gun were conducted for rigid flat-headed projectiles penetrating 7075-T651 aluminum alloy targets to obtain the targets’ fracture behavior and ballistic limit.Through round bar tensile tests and flat plate shear ones, Johnson-Cook (JC) constitution model, fracture criterion parameters and a Lode angle-dependent fracture criterion were calibrated.Adopting ABAQUS finite element software, 3-D numerical simulations were done for the tests using Lode angle-dependent fracture criterion and Lode angle-independent one, respectively.The results showed that 7075-T651 aluminum alloy targets penetrated by rigid flat-headed projectiles have shear plugging damages; 7075-T651 aluminum alloy targets’ fracture is correlated to Lode parameters, in shear band, the initial failure material’s stress tri-axiality is below 0 and Lode angle is close to 0, JC fracture criterion calibrated with round bar tensile tests over-estimates the targets’ fracture strain; fracture behavior of the targets predicted with JC fracture criterion is quite different from that in tests, the ballistic limit simulated is 42% higher than the test value; while the ballistic limit simulated using Lode angle-dependent fracture criterion agrees well with the test value.