ANALYSIS OF HUMAN COMFORT ON OSCILLATING FLOOR IN RECUMBENT POSITION

Abstract

Human Body Vibration is a complex phenomenon occurring in day to day life during many activities. Exposure to whole body vibration causes a complex distribution of vibration within the body and unpleasant sensations giving rise to annoyance and discomfort result in impaired performance and health risks. Whole body vibration is influenced by extrinsic variables (express the state or environment of dynamic system such as magnitude, frequency, direction), intrinsic variables (refers to human subject natural behaviors, characteristic condition that is age, weight, gender etc.) and interfaces between human body and the vibration environment. In this research, effect of vibration magnitude and frequency on bench-to-head, bench-to-sternuin, bench-to-thigh and bench-to-calf has been studied under vertical sinusoidal vibration. Six healthy male subjects have participated in experimental work in supine posture of the recumbent subject under three excitation magnitudes (0.5, 0.75 and 1.0 m/s2 r.m.s.) in the frequency range of 2-15Hz. Using the collected data sheets, the biodynamic response is assessed using transfer function i.e. transmissibility. Moreover a four degree of freedom lumped parameter model is developed and solved in MATLAB software. The l-larmony search algorithm is the optimization technique used for determination of biornechanical parameters. The human body consists of large groups of interlinked masses, springs and dampers and therefore can behave as a dynamic system with many degrees of freedom. The experimental study reveals that there are three ranges of resonance frequencies namely at 4-5, 6-8 and 1 0-1 1 Hz for the four parts of the body which are analyzed in this study. Moreover, it is found through experimental and model comparison that the model matched the experimental data, primarily at the major peak of resonance and provides the description of the biodynamic response study of recumbent human subjects in vertical whole body vibration.