Design, fabrication, and testing of optimized flexible cylinders

This article presents the design, fabrication, and testing of multimaterial articulating cylinders with optimized periodic substructures. Genetic Optimization (NSGA-II) is used to obtain promising archetypes, which are rapidly post-processed, additively manufactured, and tested for bending and torsional rigidity. Objectives are set as structural stiffness in torsion and bending, subject to stress and maximum radial displacement constraints. A multimaterial printer allows for two material (stiff and compliant) design. Pareto Optimal structures are down selected and post processed into manufacturable designs, which are then printed. Bending and torsional rigidities are obtained via a series of static load tests, in which a known load is applied and a bending or twisting angle is measured. Design archetypes are compared via load-rotation curves. Performance in both loading environments is related back to the characteristic substructure.