Finite Element Model Updating Applied to a Lower Limb Prosthesis Through the Optimisation of Its Mechanical Properties

In the context of elite sports for lower limb amputees, the use of advanced materials and pioneering designs has enhanced athletes’ performance by improving the energy storage and return capability of prosthesis feet. The knowledge of the behaviour of these components is crucial to meet athletes’ requirements and needs. Given their inherent anisotropic nature, the modelling of these components entails fine-tuning several parameters, i.e., Young moduli, Poisson ratios and shear moduli along three directions. This research aims to develop an automated algorithm, implemented in Matlab, for the automated fitting of the material properties. An experimental modal analysis in free-free conditions has been conducted on the blade prosthetic to extract natural frequencies and mode shapes. Subsequently, in the optimisation code, modal simulations are performed on a finite element model, using Nastran. The optimisation procedure is based on the comparison to the experimental data previously evaluated. The optimisation outcomes, in terms of material properties, enable the development of a numerical model capable of predicting the experimental dynamic behaviour up to 400 Hz.