Accession Number:

ADA339287

Title:

Dynamic Behavior of Polycrystalline Tantalum

Descriptive Note:

Final rept. Jun 96-Jun 97

Corporate Author:

ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD

Personal Author(s):

Report Date:

1997-12-01

Pagination or Media Count:

46.0

Abstract:

A description for the strain-rate and temperature-dependent behavior of pure tantalum Ta at large strains is developed. An integral part of the model incorporates the kinematics of crystallographic slip, and thus, the rotation of single crystals within the material, so as to reflect the evolution of anisotropy resulting from applied mechanical deformation. Such deformation is accommodated via bulk dislocation motion and governed by interactions that may or may not be thermally assisted. The model represents each discrete slip system as a single facet in a multisurface plasticity theory, which is well suited to high-rate numerical methods explicit integration schemes. A formulation of this type allows for the complete kinematic decomposition of macroscopic material rotations and the rotations of single crystals due to motion through the lattice. Applications to high-rate deformation in polycrystals is conducted within a finite element implementation by invoking a Taylor criterion for interaction between the macroscopic and the mesoscopic single-crystal length scales. The model behavior is examined in application to high-rate problems with increasingly complex geometries homogeneous uniaxial compression, the impact of a textured cylindrical bar into a rigid anvil, and the explosive deep-drawing of a Ta disk.

Subject Categories:

  • Inorganic Chemistry
  • Crystallography
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE