An Analysis of the Effects of Finite Fluid-Suspension Pad Length on the Dynamics of a Vehicle on an Irregular Guideway

摘要

An analysis is presented which describes the heave motion of a fluid-suspended vehicle moving over a guideway in which the irregularity wavelengths may be shorter than the suspension pad length. The analytical model is applied and exact solutions obtained for the cases of plenum and peripheral jet suspensions traversing sinusoidal and pure step irregularities. The technique is shown to be applicable to general irregularity profiles and numerical procedures for the general case are briefly discussed. It is found that compared to predictions based on zero suspension pad length (uniform guideway-suspension clearance) peak acceleration and relative displacements are generally reduced by the effects of finite pad length. Thus a conservative estimate of performance will usually be obtained if pad length effects are ignored. For most vehicle configurations and speeds, however, the attenuation due to finite pad length will be insignificant near the point of maximum vehicle response (near the natural frequency). Vehicle step responses are smoothed and a slight time delay appears compared with behavior predicted from the zero pad length theory. This work suggests that design criteria based on deterministic irregularities and peak dynamic response of the vehicle system can reasonably neglect the effects of finite suspension pad length. Further work is needed to evaluate these effects for statistically described irregularities. (Author)