Effects of posture and vibration magnitude on apparent mass and pelvis rotation during exposure to whole-body vertical vibration (in special Issue on the 2nd International Conference on Whole-body Vibration Injuries)


Mansfield, N.J. and Griffin, M.J. (2002) Effects of posture and vibration magnitude on apparent mass and pelvis rotation during exposure to whole-body vertical vibration (in special Issue on the 2nd International Conference on Whole-body Vibration Injuries). Journal of Sound and Vibration, 253, (1), 93-107. (doi:10.1006/jsvi.2001.4251).

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Original Publication URL: http://dx.doi.org/10.1006/jsvi.2001.4251

Description/Abstract

The effect of variations in posture and vibration magnitude on apparent mass and seat-to-pelvis pitch transmissibility have been studied with vertical random vibration over the frequency range 1·0–20 Hz. Each of 12 subjects was exposed to 27 combinations of three vibration magnitudes (0·2, 1·0 and 2·0m/s2 r.m.s.) and nine sitting postures ("upright", "anterior lean", "posterior lean", "kyphotic", "back-on", "pelvis support", "inverted SIT-BAR" (increased pressure beneath ischial tuberosities), "bead cushion" (decreased pressure beneath ischial tuberosities) and "belt" (wearing an elasticated belt)).

Peaks in the apparent masses were observed at about 5 and 10 Hz, and in the seat-to-pelvis pitch transmissibilities at about 12 Hz. In all postures, the resonance frequencies in the apparent mass and transmissibility decreased with increased vibration magnitude, indicating a non-linear softening system. There were only small changes in apparent mass or transmissibility with posture, although peaks were lower for the apparent mass in the "kyphotic" posture and were lower for the transmissibility in the "belt" posture. The changes in apparent mass and transmissibility caused by changes in vibration magnitude were greater than the changes caused by variation in posture.

Item Type: Article
Additional Information: Special Issue edited by Iole Pinto, Massimo Bovenzi (guest editor) and Michael J. Griffin (assistant guest editor)
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Subjects: Q Science > QP Physiology
Q Science > QC Physics
Divisions: University Structure - Pre August 2011 > Institute of Sound and Vibration Research > Human Sciences
ePrint ID: 10617
Date Deposited: 08 Feb 2006
Last Modified: 27 Mar 2014 18:02
URI: http://eprints.soton.ac.uk/id/eprint/10617

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