Modeling of Superelastic Porous Materials

Although metallic implants are often used in orthopedics to replace damaged bones and worn articulations, their use has a major limitation. Indeed, the significant difference between the high rigidity of bones and conventional metallic materials produces the so-called "stress shielding" phenomenon. Since the load is almost entirely taken by the metallic implant, the neighbouring bone tissue becomes practically unloaded. Bone-resorption is then observed and the risk of a bone fracture or a loss of bone-implant union is increased.

A possible solution to this problem is to use an implant that will have a mechanical behaviour (stiffness, load-displacement curve, etc.) similar to the bone. To achieve this goal, superlastic porous material is considered.  Also, the porous material of the implant favours the osseointegration of the bone tissues inside the implant and increases the bounding condition of the implant to the bone.

The aim of this work is to develop a numerical model being able to simulate the response of superelastic porous material. The model uses equivalent properties to avoid large-scale finite element model of a real porous structure. Therefore, the part being analyzed will be assumed to be made of a bulk material (without pores) having equivalent properties that produces a similar mechanical response. In this work, the model is described and validated by experimental results.