Topology optimization for material extrusion-based additive manufacturing processes with weak bead bonding

Topology optimization (TO) is a powerful design tool that has been used to design lightweight high-performing structures. Additive manufacturing (AM) is a favoured fabrication method for TO designs because of its high precision and flexibility to realize complex optimized structures. This paper describes a new TO approach that can account for fabrication characteristics and constraints of extrusion-based AM. The fabrication process is mimicked as the design is generated by enforcing a fixed radius feature size in design outputs, and introducing a secondary material between adjacent beads. Lowering the stiffness of this additional material allows for consideration of the weak bead bonds in extrusion-printed materials and promotes continuity of design features. The user can control the radius of the discrete feature size and the relative stiffness of the weak bond. The algorithm is demonstrated on benchmark TO problems in 2D. The design results contain both a description of the physical layout of the structure and a design variable distribution that can be used as a trace for the raster path. The design results are found to respond to user specifications on bead size and relative bond weakening. Continuity of the raster path increases as the stiffness of the bead bonding decreases.

Automated summary

This paper presents a new topology optimization approach that considers the fabrication characteristics and constraints of extrusion-based additive manufacturing (AM). Through mimicking the fabrication process and introducing a fixed radius feature size, the design results promote the continuity of design features and account for weak bead bonds. The algorithm is demonstrated on benchmark problems and the design results respond to user specifications on bead size and relative bond weakening.