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Computational and Mathematical Methods in Medicine
Volume 2014, Article ID 530242, 8 pages
Research Article

Constitutive Modeling of Time-Dependent Response of Human Plantar Aponeurosis

1Department of Industrial Engineering, University of Padova, Via G. Marzolo 8, 35131 Padova, Italy
2Centre of Mechanics of Biological Materials, University of Padova, Via G. Marzolo 9, 35131 Padova, Italy
3Department of Molecular Medicine, University of Padova, Via A. Gabelli 63, 35131 Padova, Italy

Received 23 October 2013; Accepted 10 January 2014; Published 20 February 2014

Academic Editor: Thierry Busso

Copyright © 2014 P. G. Pavan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The attention is focused on the viscoelastic behavior of human plantar aponeurosis tissue. At this purpose, stress relaxation tests were developed on samples taken from the plantar aponeurosis of frozen adult donors with age ranging from 67 to 78 years, imposing three levels of strain in the physiological range (4%, 6%, and 8%) and observing stress decay for 240 s. A viscohyperelastic fiber-reinforced constitutive model with transverse isotropy was assumed to describe the time-dependent behavior of the aponeurotic tissue. This model is consistent with the structural conformation of the tissue where collagen fibers are mainly aligned with the proximal-distal direction. Constitutive model fitting to experimental data was made by implementing a stochastic-deterministic procedure. The stress relaxation was found close to 40%, independently of the level of strain applied. The agreement between experimental data and numerical results confirms the suitability of the constitutive model to describe the viscoelastic behaviour of the plantar aponeurosis.