Abstract
At room temperature, the tantalum is shown to exhibit a high and typical strain rate sensitivity.Various experimental tests including uniaxial tensile tests for the three in-plane directions,relaxation and cyclic shear tests have been conducted at room temperature in order to study the mechanical behavior of tantalum. Based on this experimental data, an elastoviscoplastic modelis developped including the initial viscoplastic anisotropy as well as the isotropic ductile damage effect. Using the framework of the thermodynamics with state variables, an appropriate state and dissipation potentials are proposed to account for, the initial viscoplastic flow anisotropy, the mixed non linear isotropic and kinematic hardenings and the isotropic ductile damage effects. Specific developments are made to introduce different isotropic type hardenings thanks to the coupling between accumulative plastic strain and the viscous or kinematic stresses. The proposed model, implemented into ABAQUS/EXPLICIT via the user subroutine Vumat, is used to simulate different experimental tests in order to determine the accurate values of the overall material parameters. The special treatment of the plane stress is addressed and allows inherently to describe anisotropic behavior. Finally, some simple 2D and 3D simulations of deep drawing tests are carried out to validate the accuracy of the proposed model.