Effect of particulate/matrix debonding on the formation of adiabatic shear bands

We use the cohesive zone failure model to simulate debonding and failure in high strain-rate plane strain deformations of a heat conducting particulate composite comprised of initially circular metallic particulates immersed in a metallic matrix, with the goal of delineating the effect of these failures on the initiation and propagation of adiabatic shear bands (ASBs). Failure is assumed to ensue at an interface between two elements when a predefined combination of the normal and the tangential tractions on that interface reaches a critical value. We postulate that the critical value of the traction in the cohesive zone failure model decreases affinely with an increase in the temperature. Both particulate and matrix materials are assumed to be isotropic, heat conducting, and to obey the von Mises yield criterion with the flow stress depending upon the effective strain, the effective strain rate, and the temperature according to the Johnson–Cook relation. The coupled transient thermomechanical problem is analyzed by the finite element method by using 3-node triangular elements and the finite calculus technique to prevent volumetric locking. It is found that the critical strength of the bond between the particulate and the matrix significantly influences the loss of strength of the entire specimen. The time of initiation of an ASB is influenced by the time when debonding ensues which depends upon the values of the critical traction and the mode-mixity parameter in the cohesive zone failure criterion. & 2009 Elsevier Ltd. All rights reserved.