6061-T651铝合金动态力学性能及J-C本构模型的修正

为合理描述6061-T651铝合金的应力流动行为,利用万能材料试验机和霍普金森压杆,分别进行准静态、高温和高应变率下的材料力学性能测试,获得材料在不同条件下的应力应变曲线。基于试验结果,修正Johnson-Cook本构模型得到MJC(Modified Johnson-Cook)模型,并标定MJC模型各项参数。为校验MJC模型及参数的有效性,利用一级气炮发射直径为5.95mm的圆柱弹体冲击刚性靶的Taylor杆试验以及直径为12.68mm的刚性弹撞击厚度为2mm靶板的试验。最后,采用ABAQUS/Explicit有限元软件建立Taylor杆和弹靶冲击试验的三维模型,基于MJC本构模型进行Taylor杆冲击、以及结合MMC(ModifiedMohr-Coulomb)断裂准则进行弹靶冲击的数值模拟计算。研究结果表明,修正的MJC本构模型能够有效地描述6061-T651铝合金材料在大应变、高应变率和高温下材料的应力流动行为和变形行为。

Dynamic Mechanical Properties and Modification of J-C Constitutive Model of 6061-T651 Aluminum Alloy

In order to describe the stress-flow behavior of 6061-T651 aluminum alloy reasonably, the mechanical property of 6061-T651 aluminum alloy under quasi-static, high temperature and high strain rate are tested by universal material testing machine and Hopkinson pressure bar respectively, and the stress-strain curves of 6061-T651 aluminum alloy under different conditions are obtained. Based on the experimental results, the Johnson-Cook constitutive model is modified to obtain the Modified Johnson-Cook(MJC) model, and the parameters of the MJC model are calibrated. In order to verify the validity of MJC model and parameters, Taylor bar test is carried out for cylinder projectile with a diameter of 5.95 mm to impact rigid target, and for rigid projectile with a diameter of 12.68 mm to impact a thickness of 2 mm target plate by a one-stage gas gun. Finally, the three-dimensional impact model of Taylor rod, projectile and target are established by ABAQUS/Explicit finite element software. Based on MJC constitutive model, Taylor bar impact and Modified Mohr-Coulomb(MMC) fracture criterion are used for numerical simulation of projectile and target impact. The results show that the modified MJC constitutive model can effectively describe the stress flow behavior and deformation behavior of 6061-T651 aluminum alloy under large strain, high strain rate and high temperature.