Modeling strength and stress diffusion in hip prostheses with nano-reinforced composites

Nano-scale rigid particles or plates are investigated for their reinforcing properties used as a binding material for holding together many long fiber composites. Very strong and light laminates can be made by layering thin sheets of rigid fibers (e.g. carbon fibers, glass fibers) with epoxy resin, for example, as a filler for spaces between fibers. Saint-Venant's principle is concerned with assessing the effect of anisotropy on the decay of stresses with distance from the boundary of an elastic solid subjected to self-equilibrated end loads. The distance required for this transition is longer for rigid composites than for isotropic materials. The extra distance will allow bio-stress to be diffused to the boundary where end effects occur. This study is based on a biomimetic idea come from the mechanical behavior of biological materials as governed by underlying nanostructure, with the potential for synthesis into engineered materials. Mixing extremely small, rigid, randomly oriented nanoplates or nanotubes into the binding phase between the fibers is found to make the composite more isotropic near the ends and therefore mitigate damage.