Dynamic response of human foot subjected to mechanical vibration

Abstract

newline Prolonged exposure to mechanical vibration has been associated with many musculoskeletal, vascular, and sensorineural disorders of the foot from simple plantar fasciitis and achilles tendonitis to complex ones as Tarsal Tunnel Syndrome (TTS) and vibration white feet/toes. Foot-Transmitted Vibrations (FTV) are exposed to the occupants using vibrating equipment s or standing on vibrating platforms especially those working in underground mines. Prolonged exposure to Foot-Transmitted Vibrations (FTV) can lead to syndromes like vibration white feet/toes may result in tingling sensation, blanching of the toes and even numbness in the feet and toes. The present study was aimed to develop a multi-layered two-dimensional, plane strain finite element model from the actual cross-section of the human foot to study the stresses and strains developed in the skin and soft tissues. The foot is assumed to be in contact with a steel plate, mimicking the interaction between the foot and the work platform. The skin and the subcutaneous tissue are considered as hyper elastic and visco-elastic. The effects of loading in the form of displacements and the frequency of sinusoidal vibration on a time-dependent stress/strain distribution at various depths in the subcutaneous tissue of the foot are investigated. The displacements like 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 mm were applied in two-dimensional (2D) human foot model and the analysis was accomplished over 200 incremental steps using quasi-static analysis. Experimental analysis was conducted to evaluate the foot-transmitted vibrations using vibration test by considering the input frequency range of 5-160 Hz and muscle activity analysis was performed using electromyography (EMG) for a frequency range of 10-50 Hz. Vibration accelerations were recorded for each subject at location 1 (fifth metatarsal and calcaneus area) and location 2 (proximal phalange and navicular). Muscle activity analysis was performed during the mid-stance position and 10° inclined positions of the foot consideri