Effect of backrest on the discomfort caused by pitch oscillation in the frequency range 0.5 to 5 Hz

Abstract

There are standardised methods of predicting the vibration discomfort of a seated person caused by translational and rotational vibration at the seat pan, the backrest, and the support for the feet. However, the predictions are based on various assumptions that have not been fully investigated. This study was designed to determine how the discomfort caused by pitch oscillation depends on seating conditions (with and without a backrest). For a rigid seat with and without a rigid flat backrest, 15 subjects judged the discomfort caused by pitch oscillation over the frequency range 0.5 to 5 Hz at magnitudes in the range 0.05 to 5.0 rad.s-2 r.m.s. The rate of growth of discomfort varied between frequencies and depended on whether the backrest was present, so the relative discomfort between frequencies and the effect of the backrest on discomfort depended on the magnitude of vibration. Although the appropriate frequency weighting depends on the magnitude of vibration, at frequencies less than about 1 Hz, the discomfort caused by pitch oscillation is similar with and without a backrest, whereas at frequencies greater than about 1 Hz a backrest will tend to increase the discomfort caused by pitch oscillation.

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Identifiers

ORCID for James Arnold: orcid.org/0000-0003-1987-515X

ORCID for Michael Griffin: orcid.org/0000-0003-0743-9502

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