Analysis of post-buckling process and collapse of FCC single crystal plate under uniaxial compression based on proposed criterion of micro-crack nucleation deduced by shock wave theory

A new model for ductile fracture initiation is proposed based on a new concept, whereby ductile fracture initiation is caused by a jump in the wave velocity along the intersection line between two different stationary discontinuity bands characterized by the vanishing velocity of an acceleration wave. In the present paper, using the theory of ultrasonic wave velocity under plastic deformation proposed by the author, the micro-crack nucleation caused by a jump in the velocity along the intersection line between two discontinuity bands is verified theoretically by shock wave theory and analyzed numerically. Namely, diffuse necking, localized necking, and micro-crack nucleation diagrams, as well as the orientations of micro-cracks, are analyzed and discussed. Moreover, in order to consider the crystal orientation dependence of the ductile fracture progress, algorithms of the proposed criteria are incorporated into the finite element crystal plasticity model. The post-buckling process and collapse of FCC single crystal plates with different crystal orientations under uniaxial compression are then analyzed in detail and the dependence of the plastic buckling process on the crystal orientation is examined.