Biomechanical Effects of the Cellular Insole Structure Design on the Foot Heel during Heel Strike – A Dynamic Finite Element Analysis

• Main Authors: Yen-Ting Lin, 林嬿婷
• Other Authors: 鄧復旦
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/x549fb

碩士 === 國立臺北科技大學 === 機械工程系機電整合碩士班 === 106 === The main causes of heel pain and plantar ulcer are excessive plantar pressure and high plantar soft tissue stress. Although traditional methods are used to reduce the excessive pressure by changing the geometry and material of insoles, however, emerging 3D printing technology can be used for making shoe pad with various internal structures.There are many well-known sport shoe manufacturers are currently using this 3D printing technology to manufacture honeycomb soles, but few research was dedicated to explore the impact of honeycomb shoe soles on the foot, therefore, the purpose of this study was to use dynamic finite element analysis to simulate the initial heel strike movement, and to evaluate the biomechanical effects of different cellular structural insole designs on the heel tissues. In this study, structural units were constructed in three different geometries, and the porosity was established in different combinations, a total of 6 structures consisting of different cellular structures. They are defined as: 53.76%(Square-II), 58.08% (Cylinder-II), 60.89%(Hex-II), 65.27% (Cylinder-I), 68.04%(Square-I), 70.36%(Hex-I) respectively, and we used the three-dimensional finite element model of the heel, including calcaneus, soft tissue, macrochamber and microchamber, combining with the kinematics of the calcaneus to simulate the initial heel movement during heel strike, and to evaluate the biomechanical effects of different cellular structural insole designs on the heel. The results of this study showed that the effects of cellular structure on the plantar pressure and soft tissue stress and strain were not identical, the most effective group for plantar pressure redution is Cylinder-I, its pressure reduction ratio is 12.15% when compared with the pressure in barefoot condition, and the highest rate of stress and strain reduction in soft tissue is Hex-I, its stress and strain reduction ratios compared with barefoot for macro-chamber regions were 11.86% and 11.85%, and those ratios compared with barefoot for micro-chambers were 21.77% and 20.61% respectively, this phenomenon is the same as the conclusion proposed by Ibrahim’s research in 2013. The cellular structure of the shoe pad can reduce the compression stiffness of the insoles, the plantar pressure, and the strain and stress peak values of the soft tissue effectively. The analysis and experimental process of this study can be used as a preliminary assessment of the biomechanical effects of cellular insole designs on the heel, and provide a reference for designing suitable cellular structure in the subsequent whole shoe design.