The apparent mass of the seated human body in the fore-and-aft and lateral directions

Fairley, Thomas E.; Griffin, Michael J.

doi:10.1016/0022-460x(90)90890-c

Cited by 90 publications

(98 citation statements)

References 2 publications

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“…The findings seem partially consistent with the hypothesis of Shoenberger and Harris (1971) that the greatest exponents will occur at the whole-body resonance frequency; they determined exponents for vertical vibration at 3.5, 5, 7, 9, 11, 15, and 20 Hz and found that the exponent at 5 Hz (1.04) was significantly greater than that at 7, 15 and 20 Hz. The primary resonance frequencies for fore-and-aft, lateral and vertical whole-body vibration (without backrest) are in the region of 2.5, 2.0, and 4.0 Hz, respectively [24,25], which more-or-less coincide with the maximum exponent for fore-andaft vibration (at 2 Hz) and the maximum exponent for vertical vibration (at 4 Hz) in the present study. In the lateral direction, the study of Fairley and Griffin [25] had subjects with feet close together whereas in the present study the feet were further apart -this may have increased the resonance frequency of the body in the lateral direction in the present study and so a maximum exponent for lateral vibration in the 4 to 6 Hz range may also be associated (in some undefined way) with the biodynamic responses of the body during vibration.…”

Section: Fig 5 About Heresupporting

confidence: 67%

“…In the fore-and-aft and lateral directions there are resonances at about 1.5 and 3 Hz [25]. The present results show greatest subjective response to vertical vibration around 5 to 10 Hz and greatest sensitivity to horizontal vibration around 2 Hz,suggesting that the increased discomfort around these frequencies was associated with resonance of the body.…”

Section: Fig 8 About Heresupporting

confidence: 48%

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Magnitude-dependence of equivalent comfort contours for fore-and-aft, lateral and vertical whole-body vibration

Morioka¹,

Griffin²

2006

Journal of Sound and Vibration

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Section: Fig 5 About Heresupporting

confidence: 67%

Section: Fig 8 About Heresupporting

confidence: 48%

Magnitude-dependence of equivalent comfort contours for fore-and-aft, lateral and vertical whole-body vibration

Morioka¹,

Griffin²

2006

Journal of Sound and Vibration

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“…kr and cr), indicating that the first peak in the fore-andaft apparent mass is produced by a rotational vibration mode (Figures 9 and 10). This is consistent with previous studies, which reported that the first peak in the fore-and-aft apparent mass is produced by sway of the body when exposed to fore-and-aft vibration while sitting without a backrest [10,24]. This behaviour can be explained easily if one visualises the upper body on the seat as an inverted pendulum on a cart.…”

Section: Sensitivity Analysissupporting

confidence: 92%

“…the body) undergoes a sway motion. When a backrest was used, it provided a support for the body and the sway motion disappeared, as reported in [11,24]. The high variability in the parameters of the rotational degrees-of-freedom, kr and cr (Tables 1 and 2), could be attributed to the differences in the masses and dimensions of the subjects.…”

Section: Sensitivity Analysismentioning

confidence: 73%

“…Previous studies have reported an effect of sitting posture and seating condition on the fore-and-aft apparent mass (e.g. [10,11,24]) and on the vibration transmitted through the seat to the driver and passengers [25]. Using a footrest or a backrest or changing the posture, for example from slouched to erect, may change the response owing to a possible change in body mass distribution, a change in the stiffness and/or a change in the damping, which could lead to different sets of model parameters with different postures or seating conditions.…”

Section: Sensitivity Analysismentioning

confidence: 99%

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A mathematical model of the apparent mass of the human body under fore-and-aft whole-body vibration

Nawayseh¹

2022

Int. J. Automot. Mech. Eng.

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Studies of biodynamic responses to vibration have mainly focused on vertical vibration, despite the presence of high fore-and-aft and lateral vibration in some vibration environments. Consequently, models of the biodynamic responses to vibration in directions other than vertical are rare. This paper presents a model of the apparent mass of the human body during fore-and-aft vibration. The model is a two-degrees-of-freedom lumped parameter linear model with translational and rotational capabilities. The parameters of the model were optimised using experimentally measured apparent mass. The model gave a close fit to the measured apparent masses of 12 subjects. The parameters of the rotational degrees-of-freedom showed high variability, reflecting the high variability found in the measured data for the 12 subjects. Sensitivity analysis showed that the first peak of the apparent mass is produced by rotational motion while the second peak is caused by translational motion. This study showed that the fore-andaft apparent mass of the human body can be represented by a two-degrees-of-freedom system with rotational and translational capabilities. The proposed model can be integrated with a mathematical model of a seat to predict the transmissibility of the seat. Alternatively, the model parameters can be used to build a mechanical dummy that can be used experimentally for seat testing applications instead of using a human subject.

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Real‐time vibration monitoring and analysis of agricultural tractor drivers using an IoT‐based system

Singh

Nawayseh

Samuel

et al. 2023

Journal of Field Robotics

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Agricultural tractor drivers experience a high amplitude of vibration, especially during soil tillage operations. In the past, most research studied vibration exposure with more focus on the vertical (z) axis than on the fore‐and‐aft (x) and lateral (y) axes. This study examines how rotary soil tillage affects the vibration acceleration and frequency, and the power spectral densities (PSDs) at the seat pan and head along three translational axes in a real‐field multiaxis vibration context. Moreover, this study aimed to identify the characteristics of the seat‐to‐head transmissibility (STHT) response to identifying the most salient resonant frequencies along the x‐, y‐, and z‐axes. Nine (9) male tractor drivers operated the tractor with a mounted rotary tiller throughout the soil tillage process. In the event of a COVID‐19 pandemic, and to respect social distancing, this study developed an Internet of Things (IoT) module with the potential to integrate with existing data loggers for online data transmission and to make the experimentation process more effective by removing potential sources of experimenter errors. The raw acceleration data retrieved at the seat pan and the head were utilized to obtain daily exposure (A(8)), PSDs, and STHT along the x‐, y‐, and z‐axes. The vibration energy was found to be dominant along the z‐axis than the x‐ and y‐axes. A(8) response among tractor drivers exceeds the exposure action value explicitly stated by Directive 2002/44/EU. PSDs along the x‐, y‐, and z‐axes depicted the low‐frequency vibration induced by rotary soil tillage operation. The STHT response exhibited a higher degree of transmissibility along the y‐ and z‐axes when compared with that along the x‐axis. The frequency range of 4–7 Hz may plausibly be associated with cognitive impairment in tractor drivers during rotary soil tillage.

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The apparent mass of the seated human body in the fore-and-aft and lateral directions

Cited by 90 publications

References 2 publications

Magnitude-dependence of equivalent comfort contours for fore-and-aft, lateral and vertical whole-body vibration

Magnitude-dependence of equivalent comfort contours for fore-and-aft, lateral and vertical whole-body vibration

A mathematical model of the apparent mass of the human body under fore-and-aft whole-body vibration

Real‐time vibration monitoring and analysis of agricultural tractor drivers using an IoT‐based system

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