Investigation of foot biomechanics for barefoot running footwear using finite element method
Date of Issue2016-05-27
School of Mechanical and Aerospace Engineering
At present, most of the research carried out on barefoot running were concentrated on the experimental investigations especially in kinematic and kinetic studies on barefoot running and shod running. Generally, it is not always possible to investigate the stress distribution and concentration on the foot through experimentation with human subjects. In recent years, numerical methods such as finite element (FE) method has been used increasingly and successfully in many biomechanical investigations due to its ability to model structures with irregular geometry and complex material properties with complicated boundary and loading conditions for both static and dynamic analysis. Thus, in this study, FE method was used to investigate the foot biomechanics. In this thesis, a detailed three dimensional (3D) FE model of human foot and ankle was developed based on Magnetic Resonance Images (MRI) and validated through comparing the current predicted plantar pressure distribution with the data collected from experiments and previously published experimental data and FE predicted results. The FE model was then used to successfully investigate the stress distribution and concentration during inversion landing and eversion landing and barefoot running using forefoot strike (FFS) pattern. Finally, a coupled FE model of foot and barefoot running footwear have been constructed to minimize the impact and have better pressure distribution. The stress distribution in the forefoot regions have also been concurrently investigated. During foot landing, the forefoot region is one of the critical parts of the foot that are susceptible to injuries. Metatarsal injury is one of the most common foot injuries in sports related to landing conditions. Through the simulation results, the stresses under inversion and eversion landing conditions were found to be much higher than that those under normal landing. The peak von Mises stress during inversion landing, which occurred in the lateral metatarsals especially the fifth metatarsal. During eversion landing, the stresses in the medial metatarsals increased, and the stresses in the lateral metatarsals decreased. These simulation results are in close agreement with the clinical investigation on metatarsal injuries previously reported. Also, the predictions will contribute to a better understanding of the internal stresses and the mechanical responses to facilitate the injury prevention. Barefoot running encourages FFS pattern. Different strike patterns during running can have effects on the forces acting on the Achilles tendon, the loading rate, the magnitude of impact peak, which may be the potential factors that can cause injuries in foot and lower extremity. Through the simulation results of landing during barefoot running using FFS pattern; the peak von Mises stress occurred in the region of Achilles tendon, and the stress values increased with the increasing load applied to the support plate. The metatarsals in the forefoot region also sustained higher von Mises stresses compared with other bone components especially the third and fifth metatarsals. The simulation results showed good agreements with previous literatures suggesting that the FE model is effective in predicting the internal stress and it also leads to better understanding the biomechanical response during barefoot running. To date, FE models of foot and ankle have been developed to investigate the stress distribution in biomechanics. However, little work has been reported on running studies using coupled FE model of the foot and ankle with barefoot running footwear. The FE analysis found that the coupled model of the foot and ankle and the barefoot running footwear had more even pressure distribution and lower peak plantar pressure than those in the model of the foot and ankle. The results indicated that the peak von Mises stress in the five metatarsals experienced an increasing trend with the increasing load applied to the model. Furthermore, current coupled model of the foot and ankle and the barefoot running footwear could be simulated with high load to about 2.5 times of the body weight and even extend to 2000N. Considering the present state of the design and manufacture of current barefoot running footwear, this FE prediction has the potential to contribute to the biomechanical field without the need to involve a large number of laborious experimental investigations.
DRNTU::Engineering::Mechanical engineering::Mechanics and dynamics