Search Results

A covariance analysis technique is proposed to derive the optimal suspension parameters of an articulated freight vehicle. A performance criteria comprising vehicle ride response, suspension deflections and tire deflections related to dynamic wheel loads, is formulated for the 9 degrees-of-freedom (DOF) in-plane model of the vehicle. The range of suspension parameters to achieve four different design requirements is identified and a parametric study is performed to make initial parameter selection using the covariance analysis. The optimal suspension parameters are then identified from the results of the study. The study concludes that the proposed technique can yield the optimal solution in a convenient and highly efficient manner.

The increased number of heavy trucks on today's highways, along with the extended driving hours, resulted in increased demand for improved driving conditions and prompted concern about the dynamic pavement loads. The dynamic pavement loads are one of the major causes of pavement deterioration. Passive suspensions, while being very reliable and easily implementable, fall short of satisfying the various conflicting design requirements. The overwhelming improvement of ride quality resulting from the use of active suspensions seems to have overshadowed their effect on tire generated pavement damage. An in-plane tractor-semitrailer model is used to evaluate the relative performance of fail-safe active and passive suspensions. Both full state feedback and limited state feedback are used in the design of the active suspension.

The influence of self- and forced-steering axles on the directional dynamics of a tractor-semitrailer is investigated through computer simulations. The dynamic characteristics of a self-steering axle are analytically modeled and integrated to a three-dimensionalnonlinear directional dynamic model of the vehicle. Two forced-sleering algorithms relating !he vehicle speed and response quantities to the angle of the wheels of the steerable axle are formulated. and integrated to the nonlinear directional dynamic model of the vehicle. Computer simulations are performed to determine the directionalresponse characteristics of a tractor-semitrailer with self- and forced-steering axles for low as well as high speed maneuvers. The directional response characteristics of the vehicles with self- and forced-steering axles are discussed in view of the self-steering parameters and forced-steering gains, and compared to those of the vehicle with conventional axles.

The human body is most sensitive to low frequency whole body vibrations. Ride vibrations of off-road vehicles, caused primarily by irregular terrains, predominate in the 0.5 - 5 Hz frequency range. A suspension seat offers the simplest means to improve vehicle ride by reducing ride vibrations transmitted to the driver. A computer model of an off-road vehicle suspension seat was developed which can aid the designer in the selection of optimal suspension parameters. A parametric study was performed to determine the frequency response characteristics of the validated suspension model via computer simulation to investigate the influence of suspension parameters on the vibration transmission performance of suspension seats.

The modelling and analysis of a snowmobile are carried out to study its ride dynamics. The work is carried out in two phases. In phase 1, the various components such as shock-absorbers and suspension linkages are modelled and studied separately,. using both analytical and experimental methods. In the second phase, the mathematical model of the complete snowmobile is created which includes the component models created in phase 1. A computer simulation software was then developed to predict the dynamic behaviour of the vehicle. The kinematic analysis and design of the suspension linkages are carried out using a newly developed general purpose program for planar linkages, called GENKAD. The force-generation characteristics of the suspensions derived from this program are used in a 2-degrees-of-freedom (bounce and pitch) vehicle model to evaluate driver ride comfort. The enveloping action of the ski and track are taken into account by using a terrain pre-processor.