A topology strategy to reduce stress shielding of additively manufactured porous metallic biomaterials

Abstract

At present, the design of bone scaffolds cannot well balance the combination of suitable porosity and proper mechanical property, leading to difficultly facilitate bone tissue regeneration and avoid the stress shielding phenomenon simultaneously. In this work, a topology strategy of designing double-cone struts to reduce stress shielding of diamond-like porous metallic biomaterials while maintaining unvaried porosity was proposed. A representative volume element (RVE) method was developed to predict the elastic properties of lattice structures. For experimental verification, uniform diamond (UD) and double-cone diamond (DCD) structures were designed and fabricated by selective laser melting (SLM). Quasi-static compression experiments were conducted to obtain their mechanical responses. The elastic modulus and yield strength of DCD structures were significantly lower than those of UD lattices by 15.48% to 41.46% and by 17.41% to 46.42%, respectively, which were beneficial to match the mechanical properties with the host bone and avoid stress shielding. Composite structures of mimicking human bone were further designed. Their function of eliminating stress shielding was demonstrated by simulations and experiments, indicating that this double-cone topology strategy would possess full-potential in the field of orthopedic implants.