Static compression and fatigue behavior of heat-treated selective laser melted titanium alloy (Ti6Al4V) gyroid cylinders

Sydney Hitchon; William Anderson; Jaques S Milner; Gregory Hong; Todor Ivanov; Ryan Willing; David Holdsworth

doi:10.1016/j.jmbbm.2023.106076

Static compression and fatigue behavior of heat-treated selective laser melted titanium alloy (Ti6Al4V) gyroid cylinders

J Mech Behav Biomed Mater. 2023 Oct:146:106076. doi: 10.1016/j.jmbbm.2023.106076. Epub 2023 Aug 14.

Authors

Sydney Hitchon¹, William Anderson¹, Jaques S Milner², Gregory Hong³, Todor Ivanov², Ryan Willing⁴, David Holdsworth³

Affiliations

¹ School of Biomedical Engineering, Western University, London, Ontario, Canada; Bone and Joint Institute, Western University, London, Ontario, Canada.
² Robarts Research Institute, Western University, London, Ontario, Canada.
³ Bone and Joint Institute, Western University, London, Ontario, Canada; Robarts Research Institute, Western University, London, Ontario, Canada; Department of Medical Biophysics, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada.
⁴ School of Biomedical Engineering, Western University, London, Ontario, Canada; Bone and Joint Institute, Western University, London, Ontario, Canada; Department of Mechanical and Materials Engineering, Western University, London, Ontario, Canada. Electronic address: rwilling@uwo.ca.

PMID: 37598509
DOI: 10.1016/j.jmbbm.2023.106076

Abstract

Porous additively-manufactured structures could have a niche in orthopaedic implants, due to their potential to reduce stiffness (stress-shielding), improve bony ingrowth, and potential to house reservoirs of drug-eluting non-structural biomaterials. Computer aided design and finite element (FE) modelling plays an important role in the design of porous structured biomedical implants; however it is important to validate both their static and fatigue behaviours using experimental testing. This study compared the mechanical behaviors of titanium cylindrical gyroid structures of varying porosities using physical testing of additively manufactured prototypes and FE models. There was agreement in the measured and predicted relationships between porosity and apparent modulus of elasticity. As porosity increased (and wall thickness decreased), the structures failed at a lower number of cycles when loaded at the same percentage of their yield strengths. Calibration of the fatigue strength coefficient from a previously published value of 1586.5 MPa-1225 MPa greatly improved the fatigue life prediction accuracy for all the gyroid structures. Nevertheless, differences of up to 54% in the predicted versus experimental fatigue lives remained, which could be attributed to difficulties with how the precise time and location of failure is defined in the simulations, and/or minor differences in nominal and actual porosities. Although further calibration and validation should be explored, this study demonstrates that static and fatigue FE-modelling techniques could be used to aid in the design of porous prosthetics.

Keywords: Fatigue; Finite element modelling; Gyroids; Model validation; Selective laser melting.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Alloys
Hot Temperature*
Lasers
Materials Testing
Titanium*

Substances

titanium alloy (TiAl6V4)
Titanium
Alloys