Modelling And Parameter Sensitivity Analyses For The Vehicle Fitted With Hydraulically Interconnected Suspension System

The Hydraulically Interconnected Suspension(HIS)has received increasing attention in both the academic field and the engineering field in the past decade.In practice,the roll-plane HIS system has been employed by some of Nissan's premium vehicles to improve the vehicles' ride performance and meanwhile the handling performance.In the academic field,the previous researches about the parameter sensitivity analysis for HIS system have been conducted.However,the previous researches are limited to its relatively narrow range and insufficient depth.As a result,there are still not methodically theoretical references for the tuning of the HIS system's parameters.To counter the aforementioned problems,the dissertation combined with practical problems,further develops and perfects the researches of parameter sensitivity analysis for the roll-plane HIS system.A 9 degrees of freedom(9-DOF)vehicle model is built and verified by comparing its simulation results with the simulation results of the vehicle model in CarSim.The dissertation demonstrates the influence of the layout form on the characteristics of the HIS system resisting the roll motion by showing the flow state of the fluid inside the system in various motion-modes.The HIS model for a full-car is built based on the modular modeling method.The reasonability of the setups of HIS parameters is validated by the nearly identical matches between the HIS vehicle's and the standard vehicle's simulation results.The dissertation investigates the influence of the stiffness parameters including fluid cylinders' cross-sectional area,accumulator's volume and accumulator's static pressure on steady-state cornering.The influence path is classified by two sets of simulations of dismissing roll steer effect and considering roll steer effect,respectively.In regard to the investigation into the damping parameters,the objects of study are classified into 5 groups including accumulator valves,front pipe valves,rear pipe valves,front fluid cylinder valves and rear fluid cylinder valves.To reasonably comparing the influence of different objects of study,the concept of equivalent variation of pressure loss coefficient is proposed and set as the benchmark of comparisons.Based on the simulation results,the influence of pressure loss coefficients of various damping valves on ride performance,roll performance,cross-country ability and yaw performance is compared and analysed.In summary,the dissertation further develops and perfects the parameter sensitivity analysis for the roll-plane HIS system on the basis of previous researches.It is the first time that the attention is focused on the comprehensive influence of damping of the HIS system which is methodically studied.The dissertation is highly valuable for academic study as well as engineering application.