Dynamics Analysis Of An Articulated Frame Steer Vehicle With Torsio-Elastic Suspension

Articulated frame steer vehicles,widely employed in the forestry,agriculture and mining sectors.These vehicles are usually designed without suspension and operate on the rough terrains,are known to transmit high magnitude whole-body vibrations(WBV),which expose drivers to potentially hazardous levels of low back pain.Owing to their high mass center,relatively soft tires and large load variations,such vehicles always exhibit lower roll stability limits.And ASVs also exhibit lower directional stability thresholds,that will lead to the jack-knife and snaking tendency at a relatively high speed,which attributed to the special steering mechanism.This paper develops a three dimensional ASV model,optimize the torsio-elastic suspension to achieve a better compromise between ride and roll/yaw stability.Firstly,developd a off-road vehicle model,incorporating kineto-dynamic model of a torsio-elastic suspension,the model neglect the contributions due to articulation joint forces,and modeled the front and rear unit as a lumped mass.The random terrain elevations are also formulated which considering the low frequency coherence of the left and right terrain tracks.The model validity is demonstrated using the field-measured responses of a rear-suspended forestry vehicle.The optimal parameters of the three suspension configurations are identified by minimizing the vector sum of frequency-weighted rms accelerations a_v and frequency-weighted rotational vibration.Relative ride performance potentials of different axle suspensions are subsequently invertigated for the vehicle in terms of unweighted and frequency-weighted rms accelerations at the driver seat.The results show that the torsio-elastic suspension could efficiently attenuate the vehicle vibrations,and the fully-suspended vehicle yield most effective vibration attenuation,the suspension applied to axle of the vehicle unit supporting driver cabin is more effective in limiting driver vibration.The loading effect analysis illustrate that the torsio-elastic suspension is relatively insensitive to cariations in vehicle load.Then,an articulated frame steer mining truck is modeled in ADAMS based on a35-ton articulated frame steer mining truck.The vehicle model is integrated the torsio-elastic suspension at front-and rear-axle.The kinematic and dynamic of hydraulic steering system is formulated and modeled at the Matlab/Simulink,then Co-simulation between the ADAMS and Simulink for roll and yaw stability analysis.The validation of the ADAMS vehicle model was relayed on the vibration responses under the straight line maneuver,and hydraulic steering system validation was based on the response under the steady-turning and path-change maneuvers of vehicle.According to the roll and yaw stability measurement of articulated steer vehicles,the roll and yaw stability of unsuspended and suspended vehicle at unloaded and loaded condition is also analyzed,respectively.Finally,analyse the influence of the suspension and hydraulic steering system parameters to roll and yaw directional stability of ASV.The results illustrate that the roll and yaw stability of ASV is extreme sensitive of torsional stiffness of suspension.The initial pressure is greter influence the roll stability of the ASV,and the yaw stability of ASV is mostly affected by bulk modulus.