The aim of the present work was to investigate the stress relaxation phenomena of the heel pad region under different loading conditions. A 31-year-old healthy female was enrolled in this study and her left foot underwent both MRI and experimental compression tests. Experimental results were compared with those obtained from finite element analysis performed on numerical 3D subject-specific heel pad model built on the basis of MRI. The calcaneal fat pad tissue was described with a visco-hyperelastic model, while a fiber-reinforced hyperelastic model was formulated for the skin. The reliability and accuracy of the investigation performed was confirmed by comparing results obtained from experimental data and numerical analysis. Specifically, the mean absolute percentage error was found to be less than 1%. The evaluation of viscous phenomena can be useful for understanding the mechanical response during daily activities.
Compression test; Heel pad mechanics; Constitutive model; Numerical model.