Influence of geometrical notches and form optimization on the mechanical properties of additively manufactured lattice structures

Abstract

Over the past decades, additive manufacturing technology has replaced the conventional methods of production of lattice structures such as investment casting, expanded metal sheet and metallic wire assembly. However, this technology still requires more development in order to enable the application of lattice structures in lightweight load bearing structures. The main challenge lies in the structural integrity of additively manufactured lattice structures which holds back exploiting their lightweight potential. While recent research focuses on the influence of process parameters on the mechanical behaviour of lattice structures, less attention is given to geometrical notches issued from sharp edges induced by the structural design. This contribution handles the effect of geometrically induced notches in truss lattice structures. The static mechanical properties of truss-like unit cells are compared to, on the one hand, the common design solution which consists in implementing a fillet radius and, on the other hand, two notch stress optimization methods inspired from existing methods for two-dimensional notches. The comparison encompasses the analytical development of the aforementioned methods as well as their numerical verification and experimental validation for additively manufactured lattices made of AlSi10Mg. Resulting recommendations on design guidelines for improved mechanical properties of truss lattice structures are then discussed.