Limits of Application of Human Body Dynamics in Assessing Vibration Comfort of Seats

Politis, H.; Rakheja, Subhash; Juras, Dainius; Boileau, P.-É.; Boutin, Jérôme

doi:10.4271/2003-01-0953

Cited by 9 publications

(5 citation statements)

References 8 publications

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“…The laboratory assessments of seats have been performed, in particular, using rigid loads and human subjects and it has been established that the dynamic response of a suspension seat could be greatly influenced by the human body dynamics (Boileau and Rakheja, 1990;Tchernychouk et al, 2000). A recent study has shown that contributions of the human body dynamics are significant under high intensity and high frequency excitations, particularly for seats with high natural frequency, such as those employed in fork-lift trucks and automobiles (Politis et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Assessments of two dynamic manikins for laboratory testing of seats under whole-body vibration

Nélisse

Patra

Rakheja

et al. 2008

International Journal of Industrial Ergonomics

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Section: Introductionmentioning

confidence: 99%

Assessments of two dynamic manikins for laboratory testing of seats under whole-body vibration

Nélisse

Patra

Rakheja

et al. 2008

International Journal of Industrial Ergonomics

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“…ISO-5982 [14] has defined the range of biodynamic responses of the seated body exposed to vertical WBV under a limited range of experimental conditions, considered representative of vehicle driving, although in the absence of a back support. The defined ranges of APMS and STHT magnitude and phase have served as the basis for developing mechanical-equivalent biodynamic models of the seated body and anthropodynamic manikins for assessing vibration isolation effectiveness of vehicle seats [5][6][7]. The ranges of biodynamic responses in terms of DPMI magnitude and phase have also been defined by the German Institute for Standardization, which are also considered applicable for sitting without a back support and vertical vibration exposure [23].…”

Section: Comparison Of Responses With the Standardized Rangesmentioning

confidence: 99%

“…It has been widely suggested that biodynamic responses and models of the seated human body under representative postural and vibration conditions could help define methods for assessing potentials WBV exposure risks [4]. Furthermore, the biodynamic models are vital for design and tuning of primary and secondary vehicle suspensions, particularly the suspension at the seat, since the seated body contributes greatly to the overall vibration attenuation performance of a seat [5]. The biodynamic models would also help realize anthropodynamic manikins for efficient evaluations of suspension seats [6,7].…”

Section: Introductionmentioning

confidence: 99%

Influence of Back Support on the Sagittal Plane Biodynamic Response of Seated Human under Vertical Vibration

Yang

Rakheja²

2014

AMM

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The dynamic responses of the seated body exposed to vertical vibration are investigated at the two driving-points, formed by the upper body-backrest and buttock-pan interfaces in terms of force-motion relationships. The dynamic interactions of the seated body are characterized in the laboratory in terms of apparent masses at the two driving-points under white noise and track-measured random vertical vibration in the 0.5-40 Hz frequency range. The experiments were performed with 24 adult subjects seated on an idealized rigid seat, representing an automotive seat geometry. The vertical and fore-aft forces at the body-pan and body-backrest interfaces were measured to determine the apparent mass responses at the two driving-points. The results clearly revealed significant dynamic interactions of the upper body with the back support. The results also showed considerable influences of the vibration magnitude, body mass and the subjects’ hands position on the measured biodynamic responses.

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“…Based on previous works (Boileau, 1995;Gunston, 2002;Rebelle, 2000;Rakheja et al, 1994), a two-DOF mechanical system is considered in this study, assuming rigid mass representation of the human occupant, as shown in Figure 1. This assumption is considered valid in view of the results of a recent study which has shown that the contributions due to the seated occupant biodynamics are relatively small for low natural frequency as opposed to high natural frequency suspension seats when subjected to broad-band excitations of different magnitudes (Politis et al, 2003). Under low frequency excitations, this observation is also supported by the biodynamic responses of the seated occupant, which suggest that the body behaves similar to a rigid mass under excitations below 2 Hz (Coermann, 1962).…”

Section: Development Of Suspension Seat Model 21 Generic Modelmentioning

confidence: 99%

Performance Analysis of Suspension Seats under High Magnitude Vibration Excitations: Part 1: Model Development and Validation

Rakheja

Boileau

Wang

et al. 2003

Journal of Low Frequency Noise, Vibration and Active Control

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Performance analyses of suspension seats subject to high magnitude excitations require particular modeling considerations associated with impacts against the motion limiting elastic buffers, possible loss of contact between the seat and the occupant, and component characterization over a wide range of inputs. In this study, three different suspension seats are considered to formulate a generalized model that would be applicable under low to high magnitude excitations. The static and dynamic characteristics are evaluated in the laboratory under a wide range of excitations and seat preloads. General model structures are proposed to characterize the components of the selected suspension seats as functions of the preload and nature of excitation. A general model for the suspension seats is formulated upon integration of the component models and consideration of the potential body-hop motions. The validity of the proposed model is examined under a number of excitations representing continuous random vibration environment of different vehicles, such as urban buses and class-1 construction machinery (EM1), and transient sprung mass oscillations in the vicinity of the suspension seat natural frequency. The validity of the model is further examined for all three seats subject to amplified excitations of the urban buses and the construction machinery. The results of the study suggest that the proposed model can be effectively applied to assess the suspension performance under high magnitude excitations that induce repetitive impacts with motion limiting buffers. The influences of various design parameters on the shock and vibration isolation performance of the selected suspension seats are presented in the second part of this work. INTRODUCTIONThe vibration transmission performance of low natural frequency suspension seats, widely employed in off-road and heavy road vehicles varies with the frequency and the magnitude of the vibration excitation (Wu, 1998). Under relatively high levels of continuous vibration that cause the suspension movement within its permissible travel without contacting the motion limiting stops (buffers), the suspension seat may yield either attenuation or amplification of vibration depending upon the nature (frequency and magnitude) of vibration. Current laboratory seat performance assessment methods focus on this particular aspect of seat suspension performance (ISO 10326-1,1992; ISO 7096,2000; ISO 5007,1990).Further increase in the excitation magnitude may cause the suspension to exceed its permissible travel and result in recurring impacts against the buffers. The performance assessment of suspension seats in this category, whether conducted via experimental or analytical means, poses many challenges. A laboratory test procedure

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Limits of Application of Human Body Dynamics in Assessing Vibration Comfort of Seats

Cited by 9 publications

References 8 publications

Assessments of two dynamic manikins for laboratory testing of seats under whole-body vibration

Assessments of two dynamic manikins for laboratory testing of seats under whole-body vibration

Influence of Back Support on the Sagittal Plane Biodynamic Response of Seated Human under Vertical Vibration

Performance Analysis of Suspension Seats under High Magnitude Vibration Excitations: Part 1: Model Development and Validation

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