The effect of pore geometry on the mechanical properties of cast aluminium

Abstract

This thesis delves into the influence of pore geometry on the mechanical characteristics of High Pressure Die Cast (HPDC) aluminum. Additionally, it explores the feasibility of developing a material model capable of capturing the mechanical behavior for various types of porosity. Utilizing X-ray computed tomography Aided Engineering (XAE), pores were integrated into a virtual model, accurately mirroring those observed in the test coupons. These virtual replicas, in conjunction with Representative Volume Element (RVE) models, were employed alongside Finite Element Methods (FEM) to simulate the effects of porosity, including variations in pore shape, volume, and distribution. Significant findings indicate that larger pores and those situated near boundaries substantially diminish both material strength and ductility. An attempt was made to optimize the material model to encompass all findings from the test coupons. However, due to considerable disparities in failure strain among certain coupons, it was concluded that a single material model was inadequate for precise results. Consequently, two distinct material models were devised to address varying porosity volume fractions. The results demonstrate the potential for predicting failure in relation to porosity, with optimized models exhibiting a relatively accurate prediction of similar pore structures, with a maximum relative error of 6 % and 7 %, respectively.