Abstract
Shear fracture cannot be predicted with conventional forming limit curves even though it often limits the formability of modern engineering materials. To circumvent the need of a special set of ductile fracture experiments in addition to standard forming experiments, a hybrid experimental–numerical procedure is proposed to identify the three material parameters of the Hosford–Coulomb fracture initiation model from the same experiments that are used to identify the forming limit curve. To increase the reliability of the model identification, a cup drawing experiment is proposed to characterize the fracture response of out-of-plane shear loading. Uniaxial tension, bulge, Nakazima and drawing experiments are performed on specimens extracted from 1 mm thick aluminum 6016-T4 sheets. The anisotropic Yld2000 plasticity model with self-similar Swift-Voce hardening is identified to describe the large deformation response. The loading paths to fracture for stress states ranging from pure shear to equi-biaxial tension are obtained from detailed numerical simulations of all forming experiments. The identified material parameters of the Hosford–Coulomb model reveal that the fracture response of the aluminum 6016-T4 alloy is highly Lode angle dependent. Aside from identifying the anisotropic plasticity, the forming limit curve and the stress-state dependent fracture model, the deep drawing of a complex three-dimensional part with a triangular-shaped die is performed experimentally and simulated to validate the models at the structural level.
Published Version
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