Understanding influence of micro pores on strengths of LMDed AlSi10Mg material using a direct method based statistical multiscale framework

For mechanical components composed of AlSi10Mg material and produced by laser melting deposition (LMD), micro pores introduced during the additive manufacturing (AM) process significantly deteriorates the material performance. In order to evaluate how characteristics such as the porosity level, the shape and the spatial distribution of pores influence the ultimate strength and endurance limit of the material, a direct method based statistical framework is presented in this paper. Within this framework, a random sampling strategy is developed to bridge heterogeneities associated with two sub-scales, namely the scale of micro pores and the scale of material constituents. Through statistical analyses of results calculated from many 2.5D and 3D representative volume element (RVE) samples, the study shows that micro pores have more severe impact on endurance limit than on ultimate strength: With an averaged porosity degree of 0.71%, the former case drops for more than 20.0% while the latter case is almost unchanged. Meanwhile, compared to shape, spatial distribution of pores has a more significant influence on the endurance limit. The analysis in this paper shows that the established approach can be a viable means for studying similar AM materials and guiding reliability design of AM structures.