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Vertical vibration of seated subjects: effects of posture, vibration level, and frequency

Vertical vibration of seated subjects: effects of posture, vibration level, and frequency
Vertical vibration of seated subjects: effects of posture, vibration level, and frequency

The transmissibility of 12 seated subjects to sinusoidal vertical vibration was measured at 12 frequencies in the range of 7 to 75 Hz. Transmissibility, the ratio of seat vibration to vertical head vibration measured on a bite bar, was determined at each of 6 levels of vibration (0.2 to 4.0 m/s2 r.m.s.) in 2 body postures. The postures were defined by the body positions that maximised and minimised the sensation of vibration at the subjects' heads. Measurements of the fore and aft (ax), lateral (ay), and pitch motions of the head were measured on 3 subgroups. Posture had a very large effect on the vibration of the head with an approximate 6:1 difference in the mean vertical head vibration of the subjects between the 2 postures in the range 35 to 50 Hz. In both postures the mean transmissibility of the subjects decreased as frequency increased from 7 to 75 Hz and there were statistically significant reductions in transmissibility with increasing levels of vibration. Some results from individuals are presented to illustrate the large differences between subjects. The reactions of the subjects to the vibration are outlined and some implications of the results are discussed.

0095-6562
269-276
Griffin, M. J.
24112494-9774-40cb-91b7-5b4afe3c41b8
Griffin, M. J.
24112494-9774-40cb-91b7-5b4afe3c41b8

Griffin, M. J. (1975) Vertical vibration of seated subjects: effects of posture, vibration level, and frequency. Aviation Space and Environmental Medicine, 46 (3), 269-276.

Record type: Article

Abstract

The transmissibility of 12 seated subjects to sinusoidal vertical vibration was measured at 12 frequencies in the range of 7 to 75 Hz. Transmissibility, the ratio of seat vibration to vertical head vibration measured on a bite bar, was determined at each of 6 levels of vibration (0.2 to 4.0 m/s2 r.m.s.) in 2 body postures. The postures were defined by the body positions that maximised and minimised the sensation of vibration at the subjects' heads. Measurements of the fore and aft (ax), lateral (ay), and pitch motions of the head were measured on 3 subgroups. Posture had a very large effect on the vibration of the head with an approximate 6:1 difference in the mean vertical head vibration of the subjects between the 2 postures in the range 35 to 50 Hz. In both postures the mean transmissibility of the subjects decreased as frequency increased from 7 to 75 Hz and there were statistically significant reductions in transmissibility with increasing levels of vibration. Some results from individuals are presented to illustrate the large differences between subjects. The reactions of the subjects to the vibration are outlined and some implications of the results are discussed.

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More information

Published date: 1 December 1975

Identifiers

Local EPrints ID: 429266
URI: http://eprints.soton.ac.uk/id/eprint/429266
ISSN: 0095-6562
PURE UUID: 60aa493a-4690-412a-be54-0e5499ff9fe6
ORCID for M. J. Griffin: ORCID iD orcid.org/0000-0003-0743-9502

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Date deposited: 25 Mar 2019 17:30
Last modified: 07 Oct 2020 02:48

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