EVALUATION OF THE PARAMETERS OF A CONSTITUTIVE MODEL FOR BCC METALS BASED ON THERMAL-ACTIVATION

The aim of this paper consists in modelling the mechanical behaviour o f tantalum as an example for b.c.c. metals. The range of strain rates is between 10(-4) et 10(3) s(-1). A formalism proposed by J.R. Klepacz ko [1] and based on physical relations has been adopted. A methodology based on experiments and analysis is presented, which enables to dete rmine the parameters. Tests at constant strain rates and jump tests ar e simulated showing a good agreement with the experiments. A discussio n on deformation mechanisms gives a theoretical validation of the mode l's coefficients.