Performance Analysis of Suspension Seats under High Magnitude Vibration Excitations: II. Design Parameter Study

Abstract

The influences of suspension design parameters on the performance of three different suspension seats under high magnitude excitations were investigated using the generalized analytical model developed and validated in the first part of this work. The model was initially applied to study the influences of variations in the seated mass and suspension ride height on the response characteristics. Additional laboratory experiments were conducted and the measured data were used to demonstrate the validity of the generalized model under such variations in operating conditions for all three-suspension seats. The influences of variations in design parameters that could affect the performance under high magnitude excitations, namely suspension damping properties (low-velocity compression mode damping, damping asymmetry and high velocity damping) and properties of the elastic end-stops, on the performance measures are presented. Such influences are assessed in terms of seat effective amplitude transmissibility (SEAT), vibration dose value (VDV) ratio, peak accelerationof the seated mass and the peak force developed by the elastic end-stops. The results of the study suggest that suspension dampers with medium to high compression damping, higher rebound damping and higher high-speed damping would be desirable to realize enhanced performance under high magnitude excitations. Elastic end-stops with low stiffness are desirable to reduce the severity of the end-stop impacts.

A comparison of different models of passive seat suspensions

“…The total dynamic cushion force associated with deformation at the human cushion interface is represented by F cu and is given by equation (25).…”

Synthesis of a semi-active suspension seat for attenuation of Whole-Body Vibration and shock

“…The results obtained for the semi-active MR-damping suspension seat reveal that the proposed suspension control could achieve suspension resonance control and vibration isolation. The shock and vibration attenuation performance of a suspension seat also impose conflicting requirements on the suspension damping (Rakheja et al, 2004;Ma et al, 2006). The proposed control algorithm could be further enhanced to limit the suspension travel within the permissible ranges by applying the maximum current i H as the suspension approaches its travel limits.…”

“…Suspension seats for such vehicles are mostly designed with low natural frequency and limited travel, which permit their use in a wide range of road as well as off-road vehicles (Griffin, 1990;Rakheja et al, 2004). Exposure to high intensity vibration and shocks thus yield high magnitude suspension deflection and repetitive impacts against the elastic end-stops.…”

“…It is vital to limit the suspension travel to a reasonable level to provide a stable sitting platform for the drivers to perform the needed tasks in a safe and efficient manner. Some studies have made much effort to explore the conflicts of damping design requirements (Rakheja et al, 2004;Gunston, 2000;Karnopp et al, 1974). A higher suspension damping was desirable for improved attenuation of high intensity vibration and intermittent shock motions, particularly for vehicles with predominantly low frequency vibration.…”

Low Frequency Experimental Analysis of Dry Friction Damping in Cable Isolators

“…A common example of high level vibration is earthquake excitation where normally base isolation techniques are applied [1]. High level excitations are also common in vehicles, where passengers and drivers should be protected from this vibrations, here suspensions for seats are used, especially for large trucks [2,3].…”