Damage accumulation and ductile fracture modeling of notched specimens under biaxial loading at room temperature

This paper presents the results of ductile fracture tests conducted on axisymmetric specimens with notch made from EN AW 2024 T351 aluminum alloy. Tests were conducted for five notch radius and seven cases of biaxial, proportional loading with tensile force and torsional moment. A model of damage accumulation and fracture based on variables of stress strain state and damage on a physical plane is proposed. The fracture criterion assumes that crack initiation will occur when a certain combination of normal and shear stress on the physical plane (elliptical criterion in the tensile stress zone and Coulomb criterion in the shear stress zone) reaches a critical value dependent on the value of the damage state variable on this plane. The damage accumulation law was formulated incrementally, and the increment of the damage state variable was made dependent on the increment of plastic deformations and stress values on the physical plane. This model was successfully verified by experimental tests and numerical simulations, which are presented in papers by Derpenski and Seweryn (2016a,b).