Abstract:
This paper describes a vehicle dynamics model that captures the transient
characteristics of a passive Hydraulically Interconnected Suspension (HIS) system. The
vehicle is modeled as a lumped mass system with half-car and full-car configurations.
Detailed fluid dynamics models are developed to represent the fluid nonlinearities and
interactions between various hydraulic elements of the HIS. The developed models include
pipelines, accumulators, nonlinear damper characteristics, and dynamics of actuating pistons
and valves. Numerical integration of the second-order differential equations is carried out to
evaluate the transient characteristics of the coupled mechanical and hydraulic systems.
Vehicle performance and ride comfort are assessed from the time history of vertical
displacements and accelerations when the vehicle moves over a bump profile. Simulation
results show that the simplified half-car configuration captures the essential dynamics of the
HIS system, however, it overestimates the vehicle displacements, accelerations and hydraulic
pressure fluctuations. The developed simulation tools provide insight into various hydraulic
design parameters and directions for design improvements relevant to HIS systems.
