Induced anisotropy in the fracturing behavior of 3D printed parts analyzed by the size effect method

Abstract

This paper analyzes via the size effect method, the induced anisotropy in the fracturing behavior of 3D printed parts made using Acrylonitrile Butadiene Styrene (commonly abbreviated as ABS). The aspects of fracturing behavior considered include the strength, fracture toughness, the nonlinear fracture process zone (FPZ) size, and the degree of quasibrittleness. 3D printed ABS specimens of various sizes and various relative orientations of the pre-crack and the 3D printed layers are considered. The fracture properties are measured via fracture tests on single edge notch bending specimens. The measurements are seen to conform to the well-known size effect laws for strength and fracture toughness. It is demonstrated that the 3D printed parts exhibit considerable anisotropy in their fracturing behavior, which would not occur in the monolithic counterparts. This occurs not only for the strength and fracture toughness, but also the FPZ size and therefore the degree of quasibrittleness. The anisotropy stems from the crack path direction relative to the stacking direction of macrolayers and microlayers within a layer. The results show that these effects must be given due consideration when developing reliable designs for additively manufactured parts.