Apparent mass of the human body in the vertical direction: effect of seat backrest

Toward, M.G.R. (2003) Apparent mass of the human body in the vertical direction: effect of seat backrest. In, 38th United Kingdom Conference on Human Responses to Vibration, Gosport, UK, 17 - 19 Sep 2003. UK, Institute of Naval Medicine, 171-178.


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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 back rest, 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).

Item Type: Conference or Workshop Item (Paper)
Related URLs:
Subjects: T Technology > T Technology (General)
Q Science > QM Human anatomy
Q Science > QC Physics
Divisions : University Structure - Pre August 2011 > Institute of Sound and Vibration Research > Human Sciences
ePrint ID: 10717
Accepted Date and Publication Date:
Date Deposited: 09 Feb 2006
Last Modified: 31 Mar 2016 11:20

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