Influences of porosity shapes and sizes on stress and strain fields in the Casted Aluminum using Finite Element Modelling

Porosity is a common issue in Aluminum casting. The contemporary casting technologies have succeeded to some extent in predicting and controlling the casting defects. It is still impossible to eliminate various defects such as porosity, voids, and inclusions. It is also difficult to predict the exact shape and size of defect. Consequently, a key challenge in designing casted components is to validate durability by predicting accurate stress, strain, and strength by considering casting defects. In the present work, a set of static elastic-plastic finite element analyses (FEA) performed to obtain the stress and strain fields distribution near the voids/pores, and their resultant impact on tensile strength of Aluminum under tensile testing is studied. Using FEA, the stress and strain fields are determined for simple tensile test samples/specimens without and with voids/discontinuities modeled under a uniform displacement applied at a far field. The stress concentration is evaluated as a function of void/pore’s shape and size. From the virtual tensile test, it is found that both porosity shape and size affect the stress and strain fields; however, influence of porosity shape dominates over the porosity size. For the same applied uniform displacement level, the stress concentration around the void increases with an enlargement of pore size, and the highest local stress and strain appears near the voids/pores. This study also evaluates the relative effect of average void size, and porosity shape. It is found that the magnitude and sensitivity of stress concentration are hierarchically controlled by porosity shapes, sizes, and with its density.