Topology Optimization of Infill Structures for Additive Manufacturing Considering Structural Strength

Abstract

A topology optimization approach is proposed to design lightweight and high-strength porous infill structures for additive manufacturing. The maximum stress approximated by the p-norm function is minimized to enhance the structural strength. A local volume constraint is utilized to generate porous infill pattern. A continuation strategy on the upper bound of the local volume fraction is proposed to improve the stability of the optimization process and avoid the sharp rising of stress. An overhang constraint is utilized to make sure that the optimized infill structures are self-supporting and can support the given shell. Besides, two-field-based topology optimization formulations are used to ensure that the optimized infill structures satisfy the minimum length scale for additive manufacturing. The numerical results show that the optimized infill structures can significantly improve the structural strength compared with the optimized design of compliance minimization problem at the same weight. A compliance constraint is further imposed in the optimization model and the relation between stiffness and strength of the infill structures is also discussed.

Keywords

• infill structures strength
• topology optimization
• additive manufacturing
• <i>p</i>-norm stress