DUCTILE FRACTURE CHARACTERIZATION OF ALUMINUM ALLOY 2024-T351 USING DAMAGE PLASTICITY THEORY

This paper presents the calibration procedure for aluminum alloy 2024-T351 using a recently developed damage plasticity theory. The damage plasticity theory consists of a full three dimensional damage evolution law where the pressure sensitivity and the Lode angle dependence are included in a fracture envelope and the equivalent plastic strain is used as a time-like variable to determine the damage rate. Because of the coupled nature of the plastic strain and the damage, material parameters are calibrated from a parallel study of numerical simulations and experimental measurements. A set of 10 tests that cover a wide range stress states for both the hydrostatic pressure and the Lode angle are conducted in order to capture the fracture envelope in the interested stress range. The experimental setups include un-notched and notched round bars with three different notch radii, a doubly grooved flat plate and compressed cylinders of three different heights at two friction conditions. The detailed numerical and experimental procedure of calibration is demonstrated by using four of these tests. The accuracy of the calibrated material parameters is further assessed by the remainder of tests. Notch sensitivity in tensile round bars and the friction conditions in upsetting tests are discussed in detail. Good agreement in the tested load conditions is achieved for both the fracture patterns and the load-displacement curves.