Ductile fracture of notched aluminum alloy specimens under elevated temperature part 2-Numerical modelling and fracture criterion

摘要

Paper presents the results of the numerical modelling of axisymmetric specimens with circumferential notches made of aluminum alloy EN-AW 2024 T3 under elevated temperature. A range of notch rood radii (r(K) = 0.5, 2, 4, 8, 30 mm) is considered. The specimens underwent monotonic uniaxial loading at elevated temperature 20, 100, 200 and 300 degrees C. Stress and strain fields in whole specimens were calculated using finite element analysis (FEM). Axisymmetric finite element mesh model built of four-node elements with a bilinear shape function was used in simulations. The aim of these calculations were to determine the location of maximum stress and plastic strain in the specimen depending on the notch radius and the elevated temperature. Significant attention was paid to influence on distributions of stresses and plastic strains under uniaxial loading, elevated temperature and notch radius. It has been shown that the location of maximum stresses and plastic strains depends only on the notch radius where their value depends both on the notch radius and on the temperature. The main aim of these research was to develop new ductile fracture criterion for notched specimens taking into account elevated temperature and uniaxial loading. In this criterion assumed that the fracture initiation occurs when the normal stress on this physical plane reaches the critical value, depending on the isotropic damage state variable to, generated by plastic flow of the material (depending on the temperature).