Current research work in the Biomaterials Research Program includes:
In-vitro studies of fretting corrosion in modular hip joint implants:
We develop and perform in-vitro experiments to simulate operational conditions of implant materials in the body. Using a novel fretting corrosion testing machine that was designed and built specifically for testing head-neck taper junctions, complex force and moment profiles as a result of physiological loading can be applied to implant materials in a corrosive environment. Various parameters influencing the fretting corrosion behaviour can be studied. Examples include type of material, geometry and mechanical loading. We have also designed and made a testing unit for assembling modular hip implants to study the mechanical strength of the taper junction assembled with different impact force magnitudes and directions.
Retrieval studies and fretting corrosion damage characterisation in total hip replacement:
We perform detailed quantitative topographical and chemical characterisation of fretting wear and corrosion damage to the implant material, particularly in taper junction of retrieved implants. Clinical information including patient age/gender/weight, original diagnosis and reasons for revision, implantation time, and implant properties including materials and geometry/sizes are investigated. The implant components are characterised using advanced materials characterisation techniques such as SEM/EDS, XRD, XPS and surface profilometry to identify corrosion compounds and interactions between fretting wear and corrosion damage. We also develop new techniques for quantifying the intensity of surface damage to the material of retrieved implants objectively.
Computational modelling of fretting corrosion in metallic implants:
The severity of damage caused by fretting wear is dependent on the mechanical environment, in terms of the loads and frictional moments acting on the femoral component, as well as the local contact pressure and micro-motion. We use finite element (FE) method to analyse material removal at the contacting surfaces of the taper junction. Our advanced simulations include real geometry of the implant components with a non-linear frictional contact and elastic-plastic properties of the mating materials.
Microstructure and mechanical properties of additively manufactured titanium alloy Ti-6Al-4V for biomedical implants:
We study the microstructure and mechanical behaviour of titanium alloy fabricated by additive manufacturing techniques (selective laser melting and electron beam melting). Also, we investigate the effect of porosity on the stiffness and strength of titanium alloy.