Non-Local Damage Model to Predict the Effect of Pre-Strain on Ductile Fracture in Aluminum Alloy 5052

Abstract

Metallic components may develop plastic deformation before in-service loading (pre-strain) due to manufacturing process and/or unexpected loading. This pre-strain not only affects the yield strength of the material but also influences its fracture properties. The work presented here employed laser drilled model materials to better understand the effect of pre-strain on ductile fracture in aluminum alloy 5052. The micron-size laser drilled holes mimic voids forming during ductile fracture. These laser holes are introduced after the material has been pulled in tension to various amounts of pre-strain. The effect of pre-strain on void growth and linkage leading to fracture is studied. A non-local damage is used in a finite element model to predict linkage between voids. This non-local damage has only two adjustable parameters, namely the local failure strain in uniaxial tension and the characteristic length L which intervenes in the non-local averaging scheme. The precise arrangement of the laser holes can be exactly reproduced in the finite element model which allows the model to be validated with the experimental results.