Finite element investigations of the fluid-solid behaviour in a bio-inspired poroelastic bearing

Poroelastic materials are commonly found in biological systems, such as articulating cartilage, and the ability to predict their biphasic behaviour is a key step in the understanding of joint health and the development of biomimetic devices. Here, a fully coupled three dimensional finite element study is presented to demonstrate the permeability dependent load carrying capacity of fluid pressure in a time-varying poroelastic system. A bio-inspired material model is demonstrated with relaxation simulations which first show results for a cartilage-like sample and then for a variation of permeability from 10⁻¹⁹m² to 10⁻¹³m².The relaxation rate is non-linear but the total relaxation time scales linearly with permeability. That material model is then demonstrated in the context of a mechanical bearing operating in lubricated contact with an impermeable wall. The results show that for a given set of operating conditions the permeability modifies how the fluid and solid phases accommodate applied loads. High fluid load support varies through the thickness and width of the bearing. It is particularly high around regions where the interstitial flow is restricted by external factors such as contact interfaces. The model offers a novel method to predict local pressures and stresses within a poroelastic material.