Finite element simulation of mode I dynamic, ductile fracture initiation

Abstract

In this work, two dimensional (plane strain) finite element analysis of a ductile three-point bend fracture specimen subjected to mode I quasistatic and dynamic (impact-like) loading is conducted. The Gurson constitutive model that accounts for the ductile failure mechanisms of micro-void nucleation, growth and coalescence is employed within the framework of a finite deformation plasticity theory. The interaction between the notch tip and a pre-nucleated hole ahead of it is modelled. Several dynamic analyses are performed considering rate-independent and rate-dependent material behaviour and with different impact speeds. The development of ductile failure is studied by monitoring the growth of the hole and the accumulation of the micro-void damage in the ligament between the hole and the notch tip. It is observed from the above analyses that though the effect of inertia on dynamic, ductile fracture initiation is moderate, strain rate sensitivity has a strong effect on many aspects of this phenomenon.