| Abstract: | In this article we study the influence of double strain gradient, reflecting microstructural inhomogeneities, on the instability regime of a thermoviscoplastic material caused by biaxial loading. A perturbation analysis proposed earlier by Dudzinski and Molinari 1991] is used. The gesults show the influence of the microstructural coefficient on the rate of growth of the instability for various values of strain hardening, strain rate sensitivity, and straining path. The role of optimal orientation is presented, and the cases of isothermal and anisothermal deformation are analysed. Our results are also compared with those predicted by the aforementioned analysis. Finally, a comparison of uniaxial and biaxial situations concerning the role of the microstructural parameter is presented. |
