In-vivo viscous properties of the heel pad by stress-relaxation experiment based on a spherical indentation

• Published in: Medical engineering & physics Vol. 50; pp. 83 - 88
• Main Authors: Suzuki, Ryo, Ito, Kohta, Lee, Taeyong, Ogihara, Naomichi
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.12.2017
• Subjects: Biomechanical Phenomena; Damping; Finite Element Analysis; Foot; Heel; Humans; Male; Materials Testing; Plantar soft tissue; Stress, Mechanical; Viscosity; Young Adult; Damping; Plantar soft tissue; Finite element analysis; Foot
• ISSN: 1350-4533; 1873-4030; 1873-4030
• DOI: 10.1016/j.medengphy.2017.10.010

•The viscoelastic material properties of the heel pad can be identified in vivo using the spherical indentation.•Established a framework for identifying parameters without conducting repetitive FE analysis.•Effective method for use in the quantification of the material properties of plantar soft tissues. Identifying the viscous properties of the plantar soft tissue is crucial not only for understanding the dynamic interaction of the foot with the ground during locomotion, but also for development of improved footwear products and therapeutic footwear interventions. In the present study, the viscous and hyperelastic material properties of the plantar soft tissue were experimentally identified using a spherical indentation test and an analytical contact model of the spherical indentation test. Force-relaxation curves of the heel pads were obtained from the indentation experiment. The curves were fit to the contact model incorporating a five-element Maxwell model to identify the viscous material parameters. The finite element method with the experimentally identified viscoelastic parameters could successfully reproduce the measured force-relaxation curves, indicating the material parameters were correctly estimated using the proposed method. Although there are some methodological limitations, the proposed framework to identify the viscous material properties may facilitate the development of subject-specific finite element modeling of the foot and other biological materials.