VIBRATION MODELLING AND ANALYSIS OF HUMAN BODY IN SITTING POSTURES INCLUDING DAMPING CONSIDERATIONS

Abstract

In this thesis, modeling of damped vibratory system of. human body and its study under sitting postures has been presented. Procedure for the vibratory modeling through anthropomorphic model has been presented. The assumptions underlying the modeling procedure are clearly stated. The mass and stiffness values of the segments are obtained using the anthropometric data and elastic modulil of bones and tissues. The effect of damping has been studied by taking 3 different sets of damping ratio values of the segment from the reported range give in the literature (29). The validation of our procedure Is done by developing the model for a 50th percentile U.S. male and comparison of its some of the natural frequencies with the experimental data of U.S. male available in the literature. In the present work two models of 16 d.o.f. corresponding to two sitting posture are considered. Frequency response of the different segments has been obtained by Matrix; Inversion method.'Vo study the effect of damping,the response of head has been obtained for 3 different sets of damping ratios.. On tht basis of this works, vibratory models of Individuals can be framed which can predict the actual frequency response with resonable accuracy. Therefore, this thesis seems to have achieved its objective with a fair success. But since human body iS a (iv) complicated biomechanical system, there is further wide scope of refinement in future to take various consideration Into account. An initial effort was made to develop a theoretical concept of modal damping ratio, which might be a very useful term in predicting the behaviour of the multidegree damped vibratory systems( ours was a 16 d. cif. damped vibratory system) Although no concrete conclusion could be made in the present thesis,at least importance of this terms was realised through all these strenous efforts.