Build orientation optimization for additive manufacturing of functionally graded material objects

Abstract

Additive manufacturing (AM) of functionally graded material (FGM) objects has garnered significant research interest in the last decade. FGM parts printed using a 3D printer are finding innovative usages in numerous applications. To move from research sample and prototypes to commercially viable functional FGM parts, it is necessary to develop an integrated approach for modeling, optimization, and process planning for AM fabricated FGM parts. While solid modeling of FGM objects has been studied in detail, the build orientation optimization and process planning for AM fabricated FGM objects remain largely unaddressed. The build orientation of FGM object can significantly influence overall print quality and cost. In this paper, we introduce a novel approach for build orientation optimization (BOO) of additively fabricated FGM parts. The formulated BOO cost function encapsulates material error and geometric error as primary factors. The geometric error considers volumetric stair-case error and the material error accounts for errors due to the discretization of material composition across the cross-section of the toolpath. A novel multi-scale material error computation approach has been proposed to effectively and efficiently compute the material error. Since the build orientation cost function cannot be explicitly defined, and an expansive parametric sweep is too computationally expensive to implement, a surrogate model-based global optimization was implemented to solve the formulated BOO problem. The proposed optimization framework has been assessed using various test objects to illustrate the overall methodology and demonstrate its effectiveness.