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.
Keywords:Vehicle dynamics, suspension system, hydraulic interconnection, ride performance, numerical simulation