Nonlocal modeling in high-velocity impact failure of 6061-T6 aluminum

摘要

In this paper, we present numerical simulations with local and nonlocalmodels under dynamic loading conditions. We show that for finite element (FE)computations of high-velocity, impact problems with softening material modelswill result in spurious post-bifurcation mesh dependency solutions. Toalleviate numerical instability associated within the post-bifurcation regime,a characteristic length scale was added to the constitutive relations based oncalibration of the series of different notch specimen tests. This work aims toassess the practical relevance of the modified model to yield mesh independentresults in the numerical simulations of high-velocity impact problems. To thisend, we consider the problem of a rigid projectile moving at a range ofvelocities between 89-107 m/s, colliding against a 6061-T6 Aluminum disk. Amaterial model embedded with a characteristic length scale in the mannerproposed by Pijaudier-Cabot and Bazant (1987), but in the context of concretedamage, was utilized to describe the damage response of the disk. The numericalresult shows that the addition of a characteristic length scale to theconstitutive model does eliminate the pathological mesh dependency and showsexcellent agreements between numerical and experimental results. Furthermore,the application of a nonlocal model for higher strain rate behavior shows theability of the model to address intense localized deformations, irreversibleflow, softening, and final failure.