Tensile properties of multi-material interfaces in 3D printed parts

Abstract

Due to continuing progress in multi-material additive manufacturing, the design space for multifunctional and functionally graded materials and structures is significantly increased. To take full advantage of this capability, a solid understanding of the interface properties is critical, as it can significantly affect the overall mechanical behavior. This paper investigates the tensile strength of multi-material interfaces fabricated via material jetting. Tensile test specimens comprising two different materials, ranging from a rigid-brittle material to a compliant-rubbery one, are experimentally tested at room temperature. Strong dependencies on the material combination and the print orientation, i.e. the orientation of the specimens with respect to the movement of the print head, are found. Interfaces between rigid and compliant materials are mostly found to be as strong as the compliant material itself, whereas interfaces between two rigid materials show strength values reduced by up to 50% for particular print orientations. The findings enable designers to design more reliable multi-material structures while avoiding adverse material combinations and part orientations. Keywords: Multi-material additive manufacturing, Material interfaces, Functionally graded materials, Material jetting, Material testing