A post-topology optimization process for overhang elimination in additive manufacturing: design workflow and experimental investigation

Although structural design complexities do not potentially pose challenges to many additive manufacturing technologies, several manufacturing constraints should be considered in the design process. One critical constraint is a structure's unsupported or overhanging features. If these features are not reduced or eliminated, they can cause a decline in part surface quality, inhibit print success, or increase production time and cost due to support printing and removal. To eliminate these features, a new post-topology optimization strategy is proposed. The design problem is first topologically optimized, then boundary identification and overhang detection are carried out. Next, additional support-free struts subject to a specified thickness and angle are introduced to support previously detected infeasible features. This addition can increase the structure's volume; therefore, an optional volume correction stage is introduced to obtain a new but lower volume fraction which will be used in the final topology optimization, boundary identification, and overhang elimination stages. Experimental and numerical load-displacement relationships are established for varying overhang angle thresholds and minimum feature sizes.