A comparison of micro, meso and macroscale FEM analysis of ductile fracture in a CT specimen (mode I)

Several methods are available to understand the process of crack initiation and propagation in ductile materials. In an attempt to achieve an overall understanding, some of these techniques were studied using a large deformation based finite element method (FEM). In the current investigation, typical crack tip blunting prior to ductile fracture behavior of a standard (CT) specimen under mode I loading condition was simulated using FEM. An attempt was made to understand the ductile fracture by numerically determining the ductile fracture toughness at three length scales: macroscopic scale (load–displacement method), mesoscopic scale (path-integral method) and microscopic scale (stretch zone width method). In addition, the characteristic distance (lc), commonly defined as the distance between the crack tip and the void responsible for eventual coalescence with the crack tip, was also studied. Although approximate, lc assumes a special significance since it links the fracture toughness to the microscopic mechanism considered responsible for ductile fracture.