Ductile crack propagation path depending on material properties: Experimental results and discussions based on numerical simulations

To ensure the structural integrity of advanced thin sheet metals in engineering applications, it is necessary to understand their ductile crack propagation behaviour. In this work, we clarified the governing factors for ductile crack propagation paths in sheet metals by the comprehensive investigation with experimental and numerical approaches. Using two types of sheet metals, a steel and an aluminium alloy, experiments with Arcan tests were performed, and the difference in the crack paths were observed and analysed. The strategy for simulating ductile fracture proposed by the authors was successfully validated with the experimental Arcan test results, and it was applied to a parametric study based on the numerical simulations for clarifying the governing factors for ductile crack propagation paths in sheet metals. The two factors, strain hardening ability and ductility diagram parameter, were confirmed to be dominant in controlling the ductile crack propagation. The findings in the parametric study explain the difference of the crack paths as observed in the experimental Arcan tests for the two materials, thus elucidating the inverse design philosophy that facilitates material design to achieve desired performance metrics in enhancing the integrity of engineering structures.