A Test Method for the Prediction of Seat Transmissibility

Fairley, Thomas E.; Griffin, Michael J.

doi:10.4271/860046

Cited by 38 publications

(22 citation statements)

References 2 publications

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“…The foam was assumed to be a pure complex stiffness element, with its mass mseat added to the mass of the plate mplate for mass cancellation. It follows that [3]:…”

Section: Table 2 About Herementioning

confidence: 99%

“…The vertical transmissibility of a seat can be determined without human subjects by: (i) using anthropodynamic dummies [2]; (ii) predicting the transmissibility from the measured seat dynamic stiffness and the measured apparent mass of the human body [3]; (iii) using mathematical models of the dynamic response of the seat and the human body [4]. Predictions of vertical seat transmissibility show differences from the transmissibility measured with human subjects, suggesting there are limitations to the models or the associated assumptions.…”

Section: Introductionmentioning

confidence: 99%

“…The dynamic stiffness of a seat is measured using rigid indenters of specific size and shape [4] [8], or derived from curve fitting of transmissibility data [5], with little study of the effect of contact area, contact shape, vibration magnitude and vibration spectral content. The dynamic stiffness of foam also varies with changes in the weight it supports [3] [4], and it is not clear how vibration magnitude, subject weight, and contact area combine to determine the dynamic stiffness of seating foam [5][8] [9] [10].…”

Section: Introductionmentioning

confidence: 99%

“…Consequently, the vertical transmissibilities of seats are nonlinear, with the resonance frequencies reducing as the vibration magnitude increases [3] [5]. While the effect of vibration magnitude [14] and spectral content [15] on human apparent mass has been studied, it is not yet possible to predict how the apparent mass of the human body varies with the vibration input.…”

Section: Introductionmentioning

confidence: 99%

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Nonlinearity in the vertical transmissibility of seating: the role of the human body apparent mass and seat dynamic stiffness

Tufano

Griffin

2013

Vehicle System Dynamics

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The efficiency of a seat in reducing vibration depends on the characteristics of the vibration, the dynamic characteristics of the seat, and the dynamic characteristics of the person sitting on the seat. However, it is not known whether seat cushions influence the dynamic response of the human body, whether the human body influences the dynamic response of seat cushions, or the relative importance of human body nonlinearity and seat nonlinearity in causing nonlinearity in measures of seat transmissibility. This study was designed to investigate the nonlinearity of coupled seat and human body systems and compare the apparent mass of the human body supported on rigid and foam seats. A frequency domain model was used to identify the dynamic parameters of seat foams and investigate their dependence on subject sitting weight and hip breadth. With 15 subjects, the force and acceleration at the seat base and acceleration at the subject interface were measured during The measurements are presented in terms of the subject apparent mass on the rigid and foam seat surfaces, and the transmissibility and dynamic stiffness of each of the foam cushions.Both the human body and the foams showed nonlinear softening behaviour, which resulted in nonlinear cushion transmissibility. The apparent masses of subjects sitting on the rigid seat and on foam cushions were similar, but with an apparent increase in damping when sitting on the foams. The foam dynamic stiffness showed complex correlations with characteristics of the human body, which differed between foams. The nonlinearities in cushion transmissibilities, expressed in terms of changes in resonance frequencies and moduli, were more dependent on human body nonlinearity than on cushion nonlinearity.Keywords: seat transmissibility; nonlinearity; apparent mass; polyurethane foam; dynamic stiffness Published as: Nonlinearity in the vertical transmissibility of seating: The role of the human body apparent mass and seat dynamic stiffness

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“…The foam was assumed to be a pure complex stiffness element, with its mass mseat added to the mass of the plate mplate for mass cancellation. It follows that [3]:…”

Section: Table 2 About Herementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Nonlinearity in the vertical transmissibility of seating: the role of the human body apparent mass and seat dynamic stiffness

Tufano

Griffin

2013

Vehicle System Dynamics

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“…Fairley and Griffin [20] reported that the apparent mass of the body measured in a rigid seat and in a car seat were similar at low frequencies but differed between 12 and 18 Hz. Differences in seat pan inclination (e.g.…”

Section: Limitations Of Modellingmentioning

confidence: 99%

The transmission of vertical vibration through seats: Influence of the characteristics of the human body

Toward

Griffin

2011

Journal of Sound and Vibration

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The transmission of vibration through a seat depends on the impedance of the seat and the apparent mass of the seat occupant. This study was designed to determine how factors affecting the apparent mass of the body (age, gender, physical characteristics, backrest contact, and magnitude of vibration) affect seat transmissibility. The transmission of vertical vibration through a car seat was measured with 80 adults (41 males and 39 females aged 18 to 65) at frequencies between 0.6 and 20 Hz with two backrest conditions (no backrest and backrest), and with three magnitudes of random vibration (0.5, 1.0, and 1.5 ms -2 r.m.s.). Linear regression models were used to study the effects of subject physical characteristics (age, gender, and anthropometry) and features of their apparent mass (resonance frequency, apparent mass at resonance and at 12 Hz) on the measured seat transmissibility. The strongest predictor of both the frequency of the principal resonance in seat transmissibility and the seat transmissibility at resonance was subject age, with other factors having only marginal effects. The transmissibility of the seat at 12 Hz depended on subject age, body mass index, and gender. Although subject weight was strongly associated with apparent mass, weight was not strongly associated with seat transmissibility. The resonance frequency of the seat decreased with increases in the magnitude of the vibration excitation and increased when subjects made contact with the backrest. Inter-subject variability in the resonance frequency and transmissibility at resonance was less with greater vibration excitation, but was largely unaffected by backrest contact. A lumped parameter seat-person model showed that changes in seat transmissibility with age can be predicted from changes in apparent mass with age, and that the dynamic stiffness of the seat appeared to increase with increased loading so as to compensate for increases in subject apparent mass associated with increased sitting weight.Author Keywords: seat transmissibility; biodynamics; seats; whole-body vibration; inter-subject variability; posture; age; weight; gender Published as: The transmission of vertical vibration through seats: influence of the characteristics of the human body. Toward, M. G. R. & Griffin, M. J. 19 Dec 2011 In : Journal of Sound and Vibration. 330, 26, p. 6526-6543. 3 Highlights > Transmissibility of a car seat measured with 80 subjects (of both genders, aged 18 to 65 years), with and without backrest. > Subject age was the strongest predictor of seat transmissibility -increased age was associated with increased resonance frequency and increased seat transmissibility at resonance. > Subject weight was not strongly associated with seat transmissibility. > Seat resonance frequency decreased with increased vibration magnitude and increased when using the backrest.

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Evaluating the Vibration Isolation of Soft Seat Cushions Using an Active Anthropodynamic Dummy

Lewis¹,

Griffin²

2002

Journal of Sound and Vibration

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A Test Method for the Prediction of Seat Transmissibility

Cited by 38 publications

References 2 publications

Nonlinearity in the vertical transmissibility of seating: the role of the human body apparent mass and seat dynamic stiffness

Nonlinearity in the vertical transmissibility of seating: the role of the human body apparent mass and seat dynamic stiffness

The transmission of vertical vibration through seats: Influence of the characteristics of the human body

Evaluating the Vibration Isolation of Soft Seat Cushions Using an Active Anthropodynamic Dummy

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