Ductile fracture criteria in prediction of slant fracture

Abstract

The ductile fracture of metallic materials is consequence of damage accumulation after straining accompanied by large plastic deformations. It is significantly dependent on the microstructure of particular material and micromechanical defects as vacancies or second phase particles. The nucleation, growth and coalescence of voids is the fracture mechanism which applies in high values of stress triaxiality. The shear mechanism appears in the region of negative stress triaxialities. Finally, the combination of both fracture mechanisms occurs in cases of moderate stress triaxialities. The crack or fracture surface in specimens or real components is often tilted approximately 45 degrees to applied load. This slant fracture is driven by shear mechanism and occurs in the plane of maximum shear stress. It was shown that coupled ductile fracture criteria are convenient for the prediction of slant fracture infinite element simulations. There is conducted analysis of slant fracture prediction ability of two chosen coupled and uncoupled criteria in the present paper. Those criteria were calibrated and applied to two different metallic materials. The prediction is validated on those calibration fracture tests at which the slant fracture was observed.