Scratching aluminium alloys – Modelling and experimental assessment of damage as function of the strain rate

Abstract

State-of-the-art forming applications, machining, and wear processes generally involve large deformations under high speeds which are often limited to surface near zones. Hence, knowledge about a material's behaviour under such conditions is essential to understand wear or deformation. In this work, two techniques are combined to study the behaviour of two aluminium alloys in the high deformation regime: numerical simulations of a fundamental wear event (scratching) of the surface parametrized with data from high-speed compression test; and experimental scratch tests for comparison. Uniaxial compression tests until 200/s were used to identify the material parameters and revealed a high strain-rate dependence of AA1050, while it was negligible for AA7075. The strain rate behaviour was implemented in the numerical simulations using a viscoplastic constitutive model according to Johnson-Cook during high velocity scratch. The numerical simulations allow to get insight in the stress-distributions during scratching at high velocities. The low velocity scratch regime was covered via experimental scratch tests. The combination of scratch experiments and numerical simulations is a promising tool for capturing the behaviour and get detailed insight into material deformation at velocities not covered by conventional scratch testers.