Simulation of ductile fracture in aluminium alloys with random or strong texture using heuristic extensions of the Gurson model

Abstract

Ductile fracture of two high-strength aluminium alloys in temper T6 is investigated using heuristic extensions of the Gurson model with non-quadratic yield criteria. Simulations of tensile tests on smooth and notched specimens made for each alloy either from cast billets with random texture or from extruded profiles with strong deformation texture are performed and compared with experiments from previous studies. The plastic anisotropy and its influence on the predicted fracture is investigated for the extruded profile materials through simulations in several tensile directions. In the heuristic extensions of the Gurson model, the Hershey–Hosford yield function is used for the materials with random texture and the anisotropic Yld2004-18p yield criterion is used for the materials with strong deformation texture. The two alloys have different fraction of constituent particles, and as a conservative assumption the initial porosity is taken equal to the particle fraction in the simulations. For each combination of alloy and processing condition (in total four combinations), the parameters governing the flow stress of the matrix material and the critical porosity at failure are determined using a single test, while the remaining tests are used for validation. Fracture is simulated by element erosion at the critical porosity. The results show that the heuristic extensions of the Gurson model give predictions of the tensile ductility with a satisfactory accuracy for the two alloys in both processing conditions.