Computationally investigating the mechanical properties and failure initiation of the ultra-ductile metallic layer of a fibre metal laminate

Abstract

Research in materials is fundamental for meeting environmental regulations which aim to reduce energy consumption in transport applications. This thesis investigates the mechanical properties and deformation mechanisms of fibre metal laminates in research papers, the project computationally investigates the mechanical properties and failure initiation of the metallic layer (aluminium) of a fibre metal laminate due to being the most susceptible to mechanical failure, the models used for this investigation are the Johnson and Cook plasticity model, Johnson and Cook failure initiation model and the failure propagation model in ductile metals. The study investigates the failure initiation by conducting computational quasi-static tensile tests beyond failure using convergent meshes on a wide selection of flat plate specimens with various notch radius to observe the evolution of equivalent plastic strain and stress triaxiality. The mechanical properties are explored by plotting the stress-strain response from elastic deformation until failure. From the investigated geometries, the results have shown the stress triaxiality is only non- uniaxial (𝜎∗ ≠ 0.33) for a flat plate specimen with two central circular notches as a range of stress triaxiality was recorded for the central circular notches models between 0.36 to 0.55. The failure prediction study has suggested the aluminium layer fails from an equivalent plastic strain of 0.024 for the uniaxial models but can be as high as 0.029 for the flat plate with the smallest central circular notches due to recording the greatest stress triaxiality (0.55). The stress-strain simulation recorded a 3.76% difference in the computational elastic modulus (64.6 GPa) from the theoretical alloy (67.1 GPa) value and the state of damage occurred at the same angle and location as similar experimental tests.