Modelling considerations in finite element analyses of ankle foot orthoses

Abstract

An asymmetric Ankle Foot Orthosis (AFO) H model was generated from leg surface data and a number of design parameters through a versatile graphics routine. The effect of modeling parameters, geometry, loading and constraints on the AFO mechanical behavior was assessed through finite element analyses. Moderate thickness non-uniformity was predicted to have a small effect on AFO stiffness although the extent of this effect may also depend on the trimline position. Variation of the heel constraints was found to have a significant effect on both the maximum stress and the moment required to produce a given rotation about the ankle axis. The magnitude and distribution of stresses in critical regions, as well as the ankle moment, were all found to depend on the distribution of imposed deformation. The results of the parametric studies point towards some possible strategies for design optimization. © 2012 WIT Press.