Design of an Additively Manufactured Torsion Bushing with a Gyroid Core Topology

This study examines the torsional behavior of an additively manufactured bushing featuring a unique topology, which includes a flexible gyroid core and rigid inner and outer sleeves. The bushing is designed and fabricated using two materials: thermoplastic polyurethane (TPU) and polylactic acid (PLA), which are interpenetrated in successive layers throughout the bushing’s thickness. First, tensile mechanical tests are conducted on both materials with different infill patterns. The 45/135 infill proves to be the most suitable, providing good stiffness, strength, ductility, and data reproducibility. Additionally, the effectiveness of the interlocking created between the two materials through the printing process is evaluated by testing different overlap lengths. With an overlap of 2 mm, the extrusion process remains unaffected, minimizing voids and defects while ensuring strong interlayer bonding. Next, the designed bushing is subjected to torsional loading under both single and repetitive angular rotations, and its response is measured in terms of torque. The aim of this study is to evaluate the suitability of TPU and PLA materials for developing a design intended for dynamic mechanical environments, serving as a proof of concept. The quasi-static results indicate the presence of local damages and a viscoelastic response of the bushing during twisting, while also demonstrating its strong ability to withstand significant angles of rotation. Quasi-static results indicate local damage and the bushing’s viscoelastic response during twisting, as well as its ability to withstand significant angles of rotation.