Structural optimization of space frame connections fabricated through additive manufacturing

Abstract

The incorporation of additive manufacturing into the architectural and structural engineering realms mainly focused on producing physical models of conventional designs that do not showcase the benefits of using this fabrication approach. Furthermore, the design of space frame structures is centred on simple geometric forms where the members are linked using standard joints with unrefined geometries, giving them their industrial aesthetic. Applying additive manufacturing to the design workflow has the potential to create custom joints with optimized structural performance and reduced fabrication lead times. This dissertation explored the application potential of topology optimization in the design and fabrication of structural nodes for space frame structures using additive manufacturing. Topology optimization was performed on a typical node of a double layer grid structure, under single and multiple load cases. The effect of various parameters that are specified in the optimization task were also investigated. Minimum member size constraints of up to 15 mm enhanced the stiffness of the optimized node by allowing the formation of slender secondary members that acted as supports to the primary load path. Post-processing consisting of smoothing and rationalisation was found to enhance the structural performance of the optimized nodes, reducing maximum stresses by up to 47 %. The mechanical performance of the topology optimized nodes was compared to parametrically designed nodes based on mesh subdivision as well as conventional node designs. The node which was simultaneously optimized to all load cases showed the most consistent structural performance, exhibiting lower stresses than both the conventional spherical nodes and the parametric nodes. Physical prototyping of the topology optimized nodes was also investigated, showcasing the applicability of additive manufacturing in the construction industry, enhancing both the structural and aesthetic qualities of space frame structures.