| Summary: | 碩士 === 中原大學 === 醫學工程研究所 === 89 === The purpose of this study was to develop a three-dimensional finite element model of a normal left foot which comprising most joints of the foot. The validity of this model was verified by comparing analysis results with experimentally measured joint contact pressures, plantar normal pressures and plantar shear stresses.
The geometry of the left foot was acquired from a 24 year male without any foot pathology by computed tomography scan. The outer contours of the bone and soft tissue were determined by an automatic contouring program, and used to generate the solid models by a CAD program (SolidWorks 99). The 4-node tetrahedral models were created and analyzed using a CAE program (Mentat 2000 and MARC 2000). The material properties were assumed to be linear elastic. A quasi-static loading scheme was employed. All nodes on the upper cross-sectional area of the shank were constrained, and a rigid plane under the foot or footwear was moving towards the foot by using 12 displacement increment control from 0 to 12 mm at 1 mm interval. The reaction forces on the constrained nodes were recovered at each increment.
The joint contact pressures obtained from the finite element analysis were found to be much lower than the experimentally measured results. This is due to the fact that the larger contact areas assumed in the finite element model. The plantar normal pressures and plantar shear stresses were compared with experimentally measured results from literature and similar trends and pressure ranges were found. When wearing flat insole or total contact insole, the plantar pressure at the heel region can be reduced 61.39% and 90.71%, respectively.
The current study proposed a validated three-dimensional foot model which can be modified to simulate other foot conditions in the future. This foot model can be useful in observing stress distributions inside the foot, and in designing footwear, and the investigation of other biomechanical behavior of the foot subjected to different ambulatory movements.
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