STUDY OF DYNAMIC RESPONSE OF STANDING SUBJECTS UNDER WHOLE BODY VIBRATION

Abstract

In present days of busy life people are using cars, buses and trains for commuting to other places or offices. They are daily exposed to vibrations not only in sitting but also in standing position in busses and trains. However, only a few studies of the transmission of floor vibration to the knees and to the heads of standing subjects have been carried out. Most of the relevant investigations concern the transmission of vertical vibration. There are many more variables that could influence the transmission of vibration in each axis, which needs to be investigated. In this study transmissibility of whole body vibration (WBV) from floor to head and floor to knee for standing posture has been studied in the present work. Six healthy male subjects were exposed to random whole-body vibration having 0.5m1s2 and lm/s2 r.m.s vibration magnitude and frequency ranges from 0.5-20 Hz. Also the effect of two hand support (handle and handrail) on floor to head transmissibility as well as on floor to knee transmissibility was studied. In vertical direction the resonance peak is observed around 4.5 Hz to 5.5 Hz at the head and knee in both postures. The transmissibility in vertical direction when vibration given in lateral direction the resonance peak is observed around 2 Hz to 3 Hz of head in both postures. The resonance peak is observed in vertical direction when vibration given in lateral direction is observed between 7 Hz to 8 Hz. The floor-to-head transmissibility of different subjects in vertical direction is slightly increased while holding the handrail as compared to holding handle