Simultaneous optimization of build orientation and topology for additive manufacturing

Abstract

The paper presents a method to optimize build orientation and topological layout simultaneously in density-based topology optimization for additive manufacturing. Support structures are required in additive manufacturing of parts of complex shape. To eliminate or reduce support structures during the additive processes, we constrain the lower bound of the overhang angle of the optimized design. In this method, the build orientation and the density field used to represent the part are simultaneously optimized to satisfy the overhang angle constraints for part self-support. While these angle constraints are locally defined on every material point over the design domain, they are transformed into two global constraints through the Heaviside projection-based aggregations. The first directional gradient based global constraint controls the overhang angle of the solid/void interface inside the design domain to eliminate the internal supports. The second density-based global constraint controls the angle of the design domain boundary to reduce the external supports. Numerical examples on both 2D and 3D linear elastic problems are presented to demonstrate the validity and efficiency of the proposed formulations in the build orientation optimization and in the overhang angle control.