Ductile Fracture in Plane Stress

Abstract

A micromechanics-based ductile fracture initiation theory is developed for high-throughput assessment of ductile failure in plane stress. A key concept is that of inhomogeneous yielding such that microscopic failure occurs in bands with the driving force being a combination of band-resolved normal and shear tractions. The new criterion is similar to the much popularized Mohr—Coulomb model, but the sensitivity of fracture initiation to the third stress invariant constitutes an emergent outcome of the formulation. Salient features of a fracture locus in plane stress are parametrically analyzed. In particular, it is shown that a finite shear ductility cannot be rationalized based on an isotropic theory that proceeds from first principles. Thus, the isotropic formulation is supplemented with an anisotropic model accounting for void rotation and shape change in order to complete the prediction of a fracture locus and compare with experiments. A wide body of experimental data from the literature is explored and a simple procedure for calibrating the theory is outlined. Comparisons with experiments are discussed in some detail.

Study of the slant fracture in solid and hollow cylinders: Experimental analysis and numerical prediction

“…This damage-by-cavitation model shows some limitations regarding the over-prediction of the microvoids evolution at final material rupture. As a result, several extensions have been made either based on the improvement of the results at low porosities or the modification of its yield function in order to describe the effects of rate loading, material instabilities, and final rupture by voids coalescence [10][11][12][13][14]. Numerous isotropic and anisotropic damage models have been proposed by many authors to improve numerical predictions or to consider other physical mechanisms [14][15][16][17][18][19][20].…”

“…As a result, several extensions have been made either based on the improvement of the results at low porosities or the modification of its yield function in order to describe the effects of rate loading, material instabilities, and final rupture by voids coalescence [10][11][12][13][14]. Numerous isotropic and anisotropic damage models have been proposed by many authors to improve numerical predictions or to consider other physical mechanisms [14][15][16][17][18][19][20]. It is obvious that a constant void volume fraction is not sufficient in describing the fracture.…”