Predicting discomfort from whole-body vertical vibration when sitting with an inclined backrest

Basri, Bazil; Griffin, Michael J.

doi:10.1016/j.apergo.2012.10.006

Cited by 51 publications

(29 citation statements)

References 31 publications

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“…In a later study, at the higher magnitudes and at frequencies greater than 1.0 Hz, there was some discomfort in the head as well as in the central parts of the body (Basri and Griffin 2013). As frequencies increased, the head became a less important location for discomfort in favour of the upper back and the lower back.…”

Section: Body Locations Showing Greatest Discomfortmentioning

confidence: 76%

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Equivalent comfort contours for fore-and-aft, lateral, and vertical whole-body vibration in the frequency range 1.0 to 10 Hz

Arnold

Griffin

2018

Ergonomics

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Standards assume vibration discomfort depends on the frequency and direction of whole-body vibration, with the same weightings for frequency and direction at all magnitudes. This study determined equivalent comfort contours from 1.0 to 10 Hz in each of three directions (fore-and-aft, lateral, vertical) at magnitudes in the range 0.1 to 3.5 ms À2 r.m.s. Twenty-four subjects sat on a rigid flat seat with and without a beanbag, altering the pressure distribution on the seat but not the transmission of vibration. The rate of growth of vibration discomfort with increasing magnitude of vibration differed between the directions of vibration and varied with the frequency of vibration. The frequency-dependence and direction-dependence of discomfort, therefore, depended on the magnitude of vibration. The beanbag did not affect the frequency-dependence or directiondependence of vibration discomfort. It is concluded that different weightings for the frequency and direction of vibration are required for low and high magnitude vibration. Practitioner summary: When evaluating whole-body vibration to predict vibration discomfort, the weightings appropriate to different frequencies and different directions of vibration should depend on the magnitude of vibration. This is overlooked in all current methods of evaluating the severity of whole-body vibration.

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Section: Body Locations Showing Greatest Discomfortmentioning

confidence: 76%

“…Jang and Griffin 2000), the inclination of backrests (e.g. Basri and Griffin 2013), effects of low frequency rotation (e.g. Beard and Griffin 2013), and the effects of mechanical shocks (e.g.…”

Section: Introductionmentioning

confidence: 99%

Equivalent comfort contours for fore-and-aft, lateral, and vertical whole-body vibration in the frequency range 1.0 to 10 Hz

Arnold

Griffin

2018

Ergonomics

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“…In this study the subjects sat in comfortable upright postures without touching a backrest and they wore a loose lap belt. Sitting posture and contact with a backrest can alter the frequency-dependence of discomfort caused by vertical vibration (Basri and Griffin, 2013) and it might be expected that with greater magnitude shocks the tightness of a belt may alter discomfort. These factors need to be taken into account when applying the findings of the study FIGURE 9 ABOUT HERE…”

Section: Comparing Equivalent Comfort Contours For Vibration and Shocmentioning

confidence: 99%

Frequency-dependence of discomfort caused by vibration and mechanical shocks

2018

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The frequency content of a mechanical shock is not confined to its fundamental frequency, so it was hypothesised that the frequency-dependence of discomfort caused by shocks with defined fundamental frequencies will differ from the frequency-dependence of sinusoidal vibration. Subjects experienced vertical vibration and vertical shocks with fundamental frequencies from 0.5 to 16 Hz and magnitudes from ±0.7 to ±9.5 ms. The rate of growth of discomfort with increasing magnitude of motion decreased with increasing frequency of both motions, so the frequency-dependence of discomfort varied with the magnitudes of both motions and no single frequency weighting will be ideal for all magnitudes. At the frequencies of sinusoidal vibration producing greatest discomfort (4-16 Hz), shocks produced less discomfort than vibration with same peak acceleration or unweighted vibration dose value. Frequency-weighted vibration dose values provided the best predictions of the discomfort caused by different frequencies and magnitudes of vibration and shock. Practitioner Summary: Human responses to vibration and shock vary according to the frequency content of the motion. The ideal frequency weighting depends on the magnitude of the motion. Standardised frequency-weighted vibration dose values estimate discomfort caused by vibration and shock but for motions containing very low frequencies the filtering is not optimum.

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“…However, seats usually have inclined backrests and it has been reported that the W c weighting overestimates the discomfort caused by x-axis vibration of inclined backrests at low frequencies and underestimates at frequencies greater than 8 Hz (Kato and Hanai, 1998;Basri and Griffin, 2011). Furthermore, with increasing inclination of a backrest there is greater support for the upper-body and the relative importance of vertical seat pan vibration is reduced (Basri and Griffin, 2012;2013). It is not known how well a SEAT value based on currently standardised weightings will predict the overall vibration discomfort when sitting in a compliant seat with an inclined backrest.…”

Section: Introductionmentioning

confidence: 99%

The application of SEAT values for predicting how compliant seats with backrests influence vibration discomfort

Basri

Griffin

2014

Applied Ergonomics

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The extent to which a seat can provide useful attenuation of vehicle vibration depends on three factors: the characteristics of the vehicle motion, the vibration transmissibility of the seat, and the sensitivity of the body to vibration. The 'seat effective amplitude transmissibility' (i.e., SEAT value) reflects how these three factors vary with the frequency and the direction of vibration so as to predict the vibration isolation efficiency of a seat. The SEAT value is mostly used to select seat cushions or seat suspensions based on the transmission of vertical vibration to the principal supporting surface of a seat. This study investigated the accuracy of SEAT values in predicting how seats with backrests influence the discomfort caused by multiple-input vibration. Twelve male subjects participated in a four-part experiment to determine equivalent comfort contours, the relative discomfort, the location of discomfort, and seat transmissibility with three foam seats and a rigid reference

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Predicting discomfort from whole-body vertical vibration when sitting with an inclined backrest

Cited by 51 publications

References 31 publications

Equivalent comfort contours for fore-and-aft, lateral, and vertical whole-body vibration in the frequency range 1.0 to 10 Hz

Equivalent comfort contours for fore-and-aft, lateral, and vertical whole-body vibration in the frequency range 1.0 to 10 Hz

Frequency-dependence of discomfort caused by vibration and mechanical shocks

The application of SEAT values for predicting how compliant seats with backrests influence vibration discomfort

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