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Nonlinear dual-axis biodynamic response of the semi-supine human body during vertical whole-body vibration

Huang, Y. and Griffin, M.J. (2008) Nonlinear dual-axis biodynamic response of the semi-supine human body during vertical whole-body vibration Journal of Sound and Vibration, 312, (1-2), pp. 296-315. (doi:10.1016/j.jsv.2007.10.046).

Record type: Article

Abstract

Nonlinear biodynamic responses are evident in many studies of the apparent masses of sitting and standing subjects in static postures that require muscle activity for postural control. In the present study, 12 male subjects adopted a relaxed semi-supine posture assumed to involve less muscle activity than during static sitting and standing. The supine subjects were exposed to two types of vertical vibration (in the x-axis of the semi-supine body): (i) continuous random vibration (0.25–20 Hz) at five magnitudes (0.125, 0.25, 0.5, 0.75, and 1.0 m s?2 rms); (ii) intermittent random vibration (0.25–20 Hz) alternately at 0.25 and 1.0 m s?2 rms. With continuous random vibration, the dominant primary resonance frequency in the median normalised apparent mass decreased from 10.35 to 7.32 Hz as the vibration magnitude increased from 0.125 to 1.0 m s?2 rms. This nonlinear response was apparent in both the vertical (x-axis) apparent mass and in the horizontal (z-axis) cross-axis apparent mass. As the vibration magnitude increased from 0.25 to 1.0 m s?2 rms, the median resonance frequency of the apparent mass with intermittent random vibration decreased from 9.28 to 8.06 Hz whereas, over the same range of magnitudes with continuous random vibration, the resonance frequency decreased from 9.62 to 7.81 Hz. The median change in the resonance frequency (between 0.25 and 1.0 m s?2 rms) was 1.37 Hz with the intermittent random vibration and 1.71 with the continuous random vibration. With the intermittent vibration, the resonance frequency was higher at the high magnitude and lower at the low magnitude than with continuous vibration of the same magnitudes. The response was typical of thixotropy that may be a primary cause of the nonlinear biodynamic responses to whole-body vibration.

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More information

Published date: 22 April 2008
Organisations: Human Sciences Group

Identifiers

Local EPrints ID: 58589
URI: http://eprints.soton.ac.uk/id/eprint/58589
ISSN: 0022-460X
PURE UUID: 24abe9f5-5465-4302-9001-b6c9976df89e
ORCID for M.J. Griffin: ORCID iD orcid.org/0000-0003-0743-9502

Catalogue record

Date deposited: 19 Aug 2008
Last modified: 17 Jul 2017 14:26

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Contributors

Author: Y. Huang
Author: M.J. Griffin ORCID iD

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