A novel approach for enhancing the fatigue lifetime of the components processed by additive manufacturing technologies

Abstract

Purpose This study aims to introduce a novel approach in form of a comprehensive software suite to help understanding and optimizing the build orientation toward maximizing the fatigue lifetime of complex geometries. The objective is to find an optimized build orientation under a given in-service loading state, which brings on smoother surfaces in stressed regions, mitigated roughness-induced stress concentration and deferred crack initiation stage. The solution addresses scenarios that no post-build surface treatment can be applied. Design/methodology/approach To account for the surface topography, the staircase induced surface roughness is registered as a function of build angle using the white light interferometry characterization, based on which the stress concentration factor (kt) is calculated. Thereafter, the developed module in “Fatlab toolbox” is used to find the optimum build angle, considering the integrated surface orientations and stress analysis under a given loading condition. Findings Surface topography creates local stress concentrations upon loading, directly influencing the fatigue lifetime. It is a well-established fact that the conditions of the staircase geometry and surface roughness affect the magnitude of the stress concentration upon loading, which is influenced by the build orientation of the component. The proposed solution suggests the best build orientation that mitigates staircase-related surface roughness. Originality/value The suggested numerical approach assists the designers with positioning of the part on the build plate to minimize the build orientation-induced surface roughness and improve the as-built fatigue lifetime of the component.