Finite element analysis (using ANSYS) of curvature-correction of in-grown human toe-nail with corrective elastic strips pasted on to the nail surface

Abstract

Ingrown toenail is a common foot problem particularly among the elderly. One of the ways to correct the ingrown toenail is to paste an elastic strip on the curved ingrown toenail so that the strip applies restoring (corrective) forces on the nail. These corrective forces tend to reduce the curvature of the ingrown toenail. This Final Year Project (FYP) focuses on the mechanical effectiveness of corrective elastic strips for the treatment of ingrown toenails. The effectiveness is studied using Finite Element Analysis (FEA) carried out in ANSYS Mechanical APDL. A 2D finite element model is used to analyse the distribution of von-Mises stress in the elastic strip and contact pressure on the toenail.

Parameters such as the thickness and material Young’s Modulus of the elastic strip are varied to understand their influence on the contact pressure and stress distribution within the toenail surface. The major observation from the FYP is that the thickness and stiffness of the strips are the two major factors that affect pressure and stress distribution significantly. The finite analysis involves modelling contact between the elastic strip and toenail. The performance of the contact model depends on several adjustable parameters such as ‘allowable tensile contact pressure’, ‘penetration tolerance’, ‘contact algorithm’ and ‘pinball region’ which are difficult to decide. An objective of this FYP is to explore and develop an optimized modelling procedures by varying these parameters.

The findings of this FYP suggest that as the thickness of the elastic strip increases, the maximum stress in the elastic strip and the maximum pressure on the toenail increase. A similar effect is observed as the material Young’s Modulus increases.