An Investigation on the stress and strain in medical hyper elastic insole in diabetic person during gait by finite element method

Document Type : Original article

Authors

1 1. MSc Manufacturing Mechanical Engineering, Department of Mechanic, Faculty of Engineering, Islamic Azad University, NajafAbad, Iran

2 2. Assistant professor, Department of Mechanic, Faculty of Engineering, Islamic Azad University, Najaf Abad, Iran

3 3. Assistant professor, Department of Biomedical Engineering, Faculty of Engineering, University of Isfahan, Isfahan, Iran

4 4. Assistant Professor, Department of Mechanic, Faculty of Engineering, Islamic Azad University, Najaf Abad, Iran

Abstract

Background and Aim: Uncontrolled diabetes can lead to diabetic foot ulcers and if it is not treated can lead to amputation. With suitable plantar pressure distribution, by changing material and arrangement of constituent layers for multi-layer insoles, the foot ulcers can be prevented or improved. In this study, single-layer and three-layer insoles made by Silicone Gel, Plastazote Foam, Polyfoam and Ethyl Vinyl Acetate foam have been compared.
Materials and Method: the materials behavior determined using a uniaxial pressure test. Then a custom-made insole was prepared and by a digitizer device, a scatter file obtained from machined sample. This file was imported in Catia software and the volumes and surfaces has been created by using a three dimensional nonlinear FEM model, for 4 single-layer and 18 combinations of three-layer insoles during dynamic test. For verification of FE results, experimental test has been done by using Pedar system.
Results: The results showed that among single-layer insoles, the Silicon Gel and Plastazote and between three-layer insoles arranging Plastazote, Silicone Gel and Ethyl Vinyl Acetate (from top to bottom) were recognized as the best combination.
Conclusions: Three-layer insole stress concentration and strain can reduce 31% Von Mises constrain stress and 30% strain with respect to one layer insole. Experimental tests using Pedar system verified this result. In dynamic mode using Pedar system, Silicon Gel one layer insole and three-layer PLZ-SG-EVA decrease plantar pressure by 30% and 54% respectively in comparison with bare foot. The method used in this research can show suitable performance of these materials when used as insole. Also this research can be helpful for analyzing insoles using finite element method.
Keyword: Hyper elastic Material, Medical Insole Diabetic, 3D Model, Pedar System

Keywords

References

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The Scientific Journal of Rehabilitation Medicine
Volume 4, Issue 3 - Serial Number 3
September and October 2015
Pages 126-137

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History

  • Receive Date: 18 July 2014
  • Revise Date: 04 February 2015
  • Accept Date: 08 May 2015
  • First Publish Date: 23 September 2015

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