A numerical approach for designing functionally stiff triply-periodic-minimal-surface structures

Abstract

Biomedical implants require stiffnesses matching those of the surrounding bone to avoid stress shielding. Triply-periodic-minimal-surface (TPMS) structures have shown promising characteristics in preventing stress shielding; however, they are limited in allowing for anisotropic stiffness properties that are typically inherent in bone. This paper presents an approach to simplifying a TPMS structure so that common geometries can be used to approximate it. The wall thickness is varied until the desired functional and directional stiffnesses are determined through finite element modelling. Validation of the finite element models is provided through the compression testing of laser powder bed fusion (LPBF) produced specimens. The displacement response to compression testing is presented along with the final structure, which closely matches the stiffness of bone. This approach has the potential to increase implant longevity and improve the lives of implant recipients.