Investigation of the interaction phenomena between foot and insole by means of a numerical approach

The biomechanical response of foot with regard to interaction phenomena occurring at interface with insole inserted in the shoe is investigated by using a numerical approach. At this purpose, a complex three-dimensional model of the foot is defined from biomedical images, while insole conformation is acquired by laser scanner technique, leading to the finite element discretization. Foot tissues are characterized by means of specific constitutive visco-hyperelastic anisotropic formulations, recalling previous research activity. The mechanical behavior of insole material is analyzed by means of experimental compression tests that highlight the geometric and material non-linear response, represented by a hyperelastic formulation, while a hyperfoam formulation is assumed for the sole. Numerical analysis considers the mid-stance phase of the gait and allows to interpret the response of overall foot, insole and sole system. The investigation represents a preliminary step of a parametric analysis addressed to support footwear design considering different configurations of components. As matter of example, the influence of variation in insole material properties is reported.