Résumé
This work concerns the analysis of the formation of multiple adiabatic shear bands in HY-100 steel. We analyze,via analytical criteria and numerical calculations, instability and shear band spacing in simple shear. The Mechanical Threshold Stress (MTS) model is used in our proposed analysis. The MTS model is based on the use of the mechanical threshold stress as an internal state variable, which successfully describes the deformation response of metals at high strain rates. We used the perturbation method to analyze the stability of a homogeneous solution of the governing equations. The smallest value of the average strain for which the perturbed homogeneous solution becomes unstable is called the critical strain or instability strain. In the few existing works in this area, the power law is widely used and leads to analytical solution. The proposed approach based on the use of the MTS model requires numerical solution for the heat equation and the evolution equation of the internal variable. The shear band spacing is computed using Wright and Ockendon’s postulate which suggests that the wavelength of the dominant instability mode with the maximum growth rate at time t0 determines the minimum spacing between shear bands. The effects of material parameters and loading conditions on the shear band spacing are discussed. The results from the MTS model are compared to those of the power law based model.