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Influence of seat cushions on vibrations in earth moving vehicles
624
HUMAN
KESPONSE
I‘0
VIBKAT:ON
Topics: Vibration Measurements ( Off-road Vehicles) ; Ride ( Of-road vibration Devices (Seats); Non-vertical Vibration (General).
Vehicles I; Anti-
T. E. Fairley and M. J. Griffin, pp. 533-536. Application of mechanical impedance methods to seat transmissibility. (4 pages, 6 figures. 1 reference) Authors’ Introduction. An understanding of the dynamics of the seat-man system is required if seats are to be designed to optimally reduce the effects of vibration on health, performance and comfort of man. Seat-design cannot be based on the dynamic response of a seat loaded with a rigid mass. International Standard 5982 defines a standard whole-body driving point mechanical impedance of the sitting human body subjected to vertical (z-axis) vibration on a hard flat seat. The Standard suggests that this information could be used in the design of isolation systems such as seats but there is no known application of the Standard for this purpose. Here, mechanical impedance methods are used to measure the dynamics of a conventional soft vehicle seat with a man sitting on it, and it is shown how these methods can be used to predict seat transmissibility. Topics: Anti-vibration Devices (Seats); Seating (General); Body Posture; Biodynamics (Mechanical Impedance). N. C. Hilyard, P. Collier, D. Douglas and G. J. McNulty, pp. 527-531. Influence of seat cushions on vibrations in earth moving vehicles. (5 pages, 6 figures, 3 references) Authors’ Introduction. Vibration amplification by vehicle seat systems has been reported previously. To account for this and establish seat, or cushion, parameters for optimum vibration isolation, it is necessary to have a realistic model for the man-seat system. Although there is evidence to show that these arrangements behave like 2-DOF systems, it appears that the only representations employed previously have been based on l-DOF mass-spring-dashpot models. Here, we describe the initial results of our studies of the modelling of vibration behaviour at the man-cushion interface. The model employed is simplistic and does not account for all the processes operating in these systems. The seats, from JCB “3CX” earth moving vehicles, consisted of injection moulded polypropylene structural foam shells with fabric/flexible PVC covered full depth high resiliency polyurethane cushions. Two load-bearing seat cushions, A (“old”) and B (“new”), having approximate dimensions 45 cm X 50 cm X 11 cm, were investigated. Topics: Anri-vibration Devices (Sears); Seating (General). A. W. Irwin, pp. 921-924. Relative influence of noise and whole body vibration on the response of humans. (4 pages, 3 figures, 2 tables, 2 references) Author’s Introduction. In the assessment of human response to combined effects of noise and vibration these aspects are often investigated separately and independent conclusions drawn. A method for assessment of human response to combined noise and vibration is presented in this paper which also includes guidance on the application of the method to particular situations and provides details of a number of case studies. Topics: Buildings; Combined Stress ( Vibration and Noise) ; Complex Vibration (Impulses). K. Hiramatsu and M. J. Griffin, pp. 917-920. A method for predicting the average stimulus intensity for non-steady vibration based on the summation of subjective magnitude. (4 pages, 5 figures, 1 reference) Authors’ Abstract. This study investigates the applicability of a method of predicting the point of subjective equality (PSE) for non-steady vibration. The method was proposed by one of the authors for predicting the sound pressure level of a steady noise which produces a subjective magnitude equal to that of a non-steady noise. Topics: Subjective Assessment (Magnitude Estimation); Complex Vibration (Impulses).
HUMAN
KESPONSE
I‘0
VIBKAT:ON
Topics: Vibration Measurements ( Off-road Vehicles) ; Ride ( Of-road vibration Devices (Seats); Non-vertical Vibration (General).
Vehicles I; Anti-
T. E. Fairley and M. J. Griffin, pp. 533-536. Application of mechanical impedance methods to seat transmissibility. (4 pages, 6 figures. 1 reference) Authors’ Introduction. An understanding of the dynamics of the seat-man system is required if seats are to be designed to optimally reduce the effects of vibration on health, performance and comfort of man. Seat-design cannot be based on the dynamic response of a seat loaded with a rigid mass. International Standard 5982 defines a standard whole-body driving point mechanical impedance of the sitting human body subjected to vertical (z-axis) vibration on a hard flat seat. The Standard suggests that this information could be used in the design of isolation systems such as seats but there is no known application of the Standard for this purpose. Here, mechanical impedance methods are used to measure the dynamics of a conventional soft vehicle seat with a man sitting on it, and it is shown how these methods can be used to predict seat transmissibility. Topics: Anti-vibration Devices (Seats); Seating (General); Body Posture; Biodynamics (Mechanical Impedance). N. C. Hilyard, P. Collier, D. Douglas and G. J. McNulty, pp. 527-531. Influence of seat cushions on vibrations in earth moving vehicles. (5 pages, 6 figures, 3 references) Authors’ Introduction. Vibration amplification by vehicle seat systems has been reported previously. To account for this and establish seat, or cushion, parameters for optimum vibration isolation, it is necessary to have a realistic model for the man-seat system. Although there is evidence to show that these arrangements behave like 2-DOF systems, it appears that the only representations employed previously have been based on l-DOF mass-spring-dashpot models. Here, we describe the initial results of our studies of the modelling of vibration behaviour at the man-cushion interface. The model employed is simplistic and does not account for all the processes operating in these systems. The seats, from JCB “3CX” earth moving vehicles, consisted of injection moulded polypropylene structural foam shells with fabric/flexible PVC covered full depth high resiliency polyurethane cushions. Two load-bearing seat cushions, A (“old”) and B (“new”), having approximate dimensions 45 cm X 50 cm X 11 cm, were investigated. Topics: Anri-vibration Devices (Sears); Seating (General). A. W. Irwin, pp. 921-924. Relative influence of noise and whole body vibration on the response of humans. (4 pages, 3 figures, 2 tables, 2 references) Author’s Introduction. In the assessment of human response to combined effects of noise and vibration these aspects are often investigated separately and independent conclusions drawn. A method for assessment of human response to combined noise and vibration is presented in this paper which also includes guidance on the application of the method to particular situations and provides details of a number of case studies. Topics: Buildings; Combined Stress ( Vibration and Noise) ; Complex Vibration (Impulses). K. Hiramatsu and M. J. Griffin, pp. 917-920. A method for predicting the average stimulus intensity for non-steady vibration based on the summation of subjective magnitude. (4 pages, 5 figures, 1 reference) Authors’ Abstract. This study investigates the applicability of a method of predicting the point of subjective equality (PSE) for non-steady vibration. The method was proposed by one of the authors for predicting the sound pressure level of a steady noise which produces a subjective magnitude equal to that of a non-steady noise. Topics: Subjective Assessment (Magnitude Estimation); Complex Vibration (Impulses).