A micromechanics-based model for micro-toughness estimation from dimple geometry measurements

Abstract

A new model for the estimation of the micro-toughness in ductile fracture is presented. Micro-toughness is defined as the plastic work dissipated per unit fracture surface area in the material separation processes of void growth and coalescence. Stereophotogrammetric measurements of the height and width of dimples on ductile fracture surfaces are used in conjunction with the model to determine the micro-toughness. A finite element model is used to validate the analytical model. With the new model the ratio between the micro-toughness as related to the fracture surface topology and the global fracture toughness ( J-integral) values become physically reasonable. The model is applied to structural steels and a metal matrix composite. Implications to computational fracture mechanics models are discussed.