Modeling Materila Failure in High Strain-Rate Problems

Virginia Polytechnic Institute And State University, Blacksburg VA

Investigators

Abstract

Modeling Material Failure in High Strain Rate Problems R. C. Batra Virginia Polytechnic Institute and State University An hyperbolic heat equation along with the equations expressing the balance of mass, linear momentum and moment of momentum for thermoviscoplastic materials will be used to delineate the initiation and propagation of adiabatic shear bands (ASBs) during high strain rate deformations of such materials. An ASB is a narrow region of intense plastic deformation that usually precedes the ductile failure of most metals and some polymers deformed at high strain rates. The heat generated due to plastic deformations of the material, heat conduction and thermal stresses induced will be accounted for. The finite element mesh will be refined adaptively and the time increment used to integrate the coupled nonlinear ordinary differential equations obtained by the Galerkin approximation of the governing equations will be adjusted adaptively so as to compute the stable solution within the prescribed accuracy. The energy dissipation rate within the shear banded material, rate of energy conducted out of the edges of the band, and the energy used to raise the temperature of the shear banded material will be computed during the development of the shear band. Its speed will be ascertained by locating its edges at different times. By modeling an ASB as a singular surface, we will determine its speed of propagation and compare it with that computed above numerically. It should be noted that an ASB is not a wave in the classical sense and it propagates edgewise rather than normal to its surface. This speed will be related to the state of deformation of the material within and adjacent to the edge of the ASB.