Identification of the Material Hardening and Failure of an Aluminum Alloy Sheet via a Simple Shear Test

Abstract

Numerical simulation of the ductile failure of sheet metals usually requires a hardening response to large strains and a reliable failure criterion. This work investigates the material hardening and shear failure of AA6061-T6 sheet using a newly designed shear specimen. A series of numerical simulations are conducted to investigate the stress and strain states in some critical regions of the specimen, and an optimized geometry is obtained that delays the localized deformation on the edges of the specimen. The newly designed shear specimen is tested using a universal testing machine and the Digital Image Correlation (DIC) technique is adopted to monitor the strain field. The von Mises equivalent strain in the test section reaches 0.79 before the specimen fractures. For comparison, two simple shear tests of AA6061-T6 sheet based on two representative shear specimen designs from the literature are conducted using the same experimental setup. The two shear specimens fail at the strain level between 0.5 and 0.6, lower than the failure strain of 0.79 obtained in ours. This comparison shows the better performance of our newly designed shear specimen in the identification of the shear failure strain of this sheet. The shear stress-strain response of our specimen is also used to establish the material hardening response up to a maximum equivalent strain of 0.56, much higher than the limit strain of 0.09 from the uniaxial tension test, which demonstrates the advantage of using appropriately designed shear specimen in the material hardening identification of sheet metals.