Ductile failure by strain localisation: A computational study of materials and structures subjected to highly non-proportional load histories

Ductile failure by the onset of strain localisation after non-proportional load paths is investigated herein by using the imperfection version of the strain localisation theory. A computational framework assuming a planar, porous imperfection band inside a homogeneous solid was used to investigate ductile failure as caused by void nucleation, growth, and coalescence. The localisation analysis framework was calibrated based on a single uniaxial tension test and finite element simulations thereof. Despite the somewhat frugal calibration, the localisation analyses successfully reproduced experimentally measured macroscopic fracture strains from notched tension tests and notched compression–tension tests. The method was subsequently applied to a structural problem involving large deformations and complex load paths, and the results show great promise for future work. • Imperfection-based strain localisation theory is used to study ductile failure. • A single tension test is used for calibration of the localisation framework. • Failure from both proportional and non-proportional loads is well captured. • The approach is applied to a pipe denting case with reversed loading. • The results correspond well with experimental observations.