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The apparent mass of the seated human body: Vertical vibration

The apparent mass of the seated human body: Vertical vibration
The apparent mass of the seated human body: Vertical vibration

Apparent mass frequency response functions of the seated human body have been measured with random vibration in the vertical direction at frequencies up to 20 Hz. A group of eight subjects was used to investigate some factors (footrest, backrest, posture, muscle tension, vibration magnitude) that may affect the apparent mass of a person; a group of 60 subjects (24 men, 24 women and 12 children) was used to investigate variability between people. Relative movement between the feet and the seat was found to affect the apparent mass at frequencies below resonance, particularly near zero-frequency. The resonance frequency generally increased with the use of a backrest, an erect posture and, in particular, increased muscle tension; but there was considerable intersubject variability in the changes. The magnitude of the vibration had a consistent effect: the resonance frequency decreased from about 6 to 4 Hz when the magnitude of the vibration was increased from 0.25 to 2.0 ms-2 r.m.s. The apparent masses of all the subjects were remarkably similar when normalized with respect to sitting weight, However, there were statistically significant correlations between apparent mass and some body characteristics (such as weight and age).

0021-9290
81-94
Fairley, Thomas E.
ee8b26bf-e15f-4c56-bfe0-263c2924c685
Griffin, Michael J.
24112494-9774-40cb-91b7-5b4afe3c41b8
Fairley, Thomas E.
ee8b26bf-e15f-4c56-bfe0-263c2924c685
Griffin, Michael J.
24112494-9774-40cb-91b7-5b4afe3c41b8

Fairley, Thomas E. and Griffin, Michael J. (1989) The apparent mass of the seated human body: Vertical vibration. Journal of Biomechanics, 22 (2), 81-94. (doi:10.1016/0021-9290(89)90031-6).

Record type: Article

Abstract

Apparent mass frequency response functions of the seated human body have been measured with random vibration in the vertical direction at frequencies up to 20 Hz. A group of eight subjects was used to investigate some factors (footrest, backrest, posture, muscle tension, vibration magnitude) that may affect the apparent mass of a person; a group of 60 subjects (24 men, 24 women and 12 children) was used to investigate variability between people. Relative movement between the feet and the seat was found to affect the apparent mass at frequencies below resonance, particularly near zero-frequency. The resonance frequency generally increased with the use of a backrest, an erect posture and, in particular, increased muscle tension; but there was considerable intersubject variability in the changes. The magnitude of the vibration had a consistent effect: the resonance frequency decreased from about 6 to 4 Hz when the magnitude of the vibration was increased from 0.25 to 2.0 ms-2 r.m.s. The apparent masses of all the subjects were remarkably similar when normalized with respect to sitting weight, However, there were statistically significant correlations between apparent mass and some body characteristics (such as weight and age).

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More information

Published date: 1989
Organisations: Human Factors Research Unit

Identifiers

Local EPrints ID: 408559
URI: http://eprints.soton.ac.uk/id/eprint/408559
ISSN: 0021-9290
PURE UUID: a93ae247-afd8-449b-af47-c17a4a9b825f
ORCID for Michael J. Griffin: ORCID iD orcid.org/0000-0003-0743-9502

Catalogue record

Date deposited: 23 May 2017 04:03
Last modified: 07 Oct 2020 02:47

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