Evaluation of modelling parameters for AA2014-T6 in simulating dynamic fracture event

Abstract

The material behavior of the aluminum alloy AA2014-T6 under different strain rates and temperatures must be examined in order to simulate their responses under extreme loading conditions like dynamic fracture and impact. In the present study, several uniaxial tensile experiments, including quasi-static, dynamic, and triaxiality, were carried out at different temperatures to evaluate the material constants for the Johnson cook constitutive and failure models of AA2014-T6. It was observed that material flow stress exhibited positive strain rate sensitivity at high strain rates and negative sensitivity when temperature increased from 25 to 250 °C. From the triaxiality experiments, it was also observed that the plastic flow increased while the ductility of the material decreased with increasing stress triaxiality. The dynamic fracture behavior of a pre-cracked 3-point bend specimen of AA2014-T6 was studied at different loading rates. Applied load and load point displacement (LPD) were measured using strain gauges. In addition, crack mouth opening displacement (CMOD) and crack initiation time were calculated using the 3D digital image correlation technique. It was found that the loading rates highly influence the dynamic fracture initiation and propagation toughness of the material. A 3D finite element simulation of dynamic 3-point bend experiments was performed in ABAQUS using the J-C damage evaluation criteria, and incident stress obtained from the dynamic experiments was used as an input load to minimize the error. In accordance, with the actual experiments conducted, the material geometry, boundary conditions, and contact circumstances were considered. The authors found good agreement between both the experimental and numerical results.