Modeling And Dynamic Analysis Of A Novel Integrated Hydro-pneumatic Suspension Strut

Suspension,as one of the most important sub-system in a modern vehicle,plays an essential role in ride & handling and safety.Damper is the core of a suspension system,and its working performance directly determines the properties of the suspension system.In general,the damper can be classified to the hydro-pneumatic suspension,air suspension,spring,rubber and so on.Hydro-pneumatic suspension is able to adapt to different loading condition,and easily adjusted based on different and complicated working condition with compacted design.Therefore,it can improve the ride comfortable ability and road handling ability,effectively.A novel integrated hydro-pneumatic suspension will be proposed in this dissertation based on the concept of integrated hydro-pneumatic suspension,proposed by Rakheja.In this research,the mathematical model of the single air chamber strut will be established based on the experimental data,and then the design scheme of the proposed twin-chamber strut will be proposed.Comparing with the traditional Hydro-pneumatic suspension design,the core issue of the proposed scheme is: under the same charging pressure(satisfying the loading requirements),the elastic coefficient of the strut still depends directly on the area difference between both sides of the main piston in the cylinder,but the effect area to push the inert gas chamber only depends on the thickness of the inner cylinder.This can provide more gentle(soft)non-linear stiffness characteristics,and achieve the specific strut characteristics by adjusting different initial charge pressure.The organization of this dissertation is following:1.Based on the existing numerical model of single-chamber hydro-pneumatic suspension,a proto-type will be designed and manufactured.The dynamic characteristics of the hydro-pneumatic suspension will be tested through the MTS system,and the experimental data will be collected through the NI data acquisition system.Based on the analysis of the experimental data,the model type and model parameter of the theoretical model will be determined.The effectiveness of the established model will verify through the experimental data.2.The theoretical model of the proposed twin-gas chamber hydro-pneumatic suspension model will be established based on its working principle(the law of the conservation mass,flow conservation law and the polytrophic process of gas,etc.)with the consideration of the oil compressibility.The effectiveness of the proposed model will be verified based on the established Virtual Prototype(VP)model by MSC/ADAMS.Good agreement can be found through the simulation data.3.The dynamic properties comparison between the single-chamber hydro-pneumatic suspension design and the twin-chamber one will be presented in the last part of this dissertation.It can be concluded that both single-chamber and twin-chamber structures have obvious non-linear stiffness characteristics,furthermore,the twin-chamber structure has more effectual carrying capacity under the same initial inflation pressure.