Research On Multi-objective Optimization Design Of Magnetorheological Damper And Simulation Of Semi-active Suspension

With the rapid development of highway and increment of vehicle velocity, thecomfort and security of automobiles have drawn more and more attention. Suspensionof vehicle, the key component which has an important influence on performance ofvehicle, plays a critical role in improving ride comfort and stability of vehicle in realtime. During past two decades, because of its rapid response, wide bandwidth, lowconsumption of energy and simple structure, the semi-active suspension usedmagneto-rheological(MR) damper has been conducted extensively by scholars andengineers. The main research contents include design methodologies and mechanicsmodeling for MR damper, modeling of suspension system and its control. However,there are few literatures involved in the influence of geometric nonlinearity induced bythe variation of spatial distances of suspension on modeling and dynamic analysis ofsuspension system and its control. Therefore, by taking a car with Macphersonsuspensions and MR dampers as the research object, MR dampers were designed bymulti-objective optimization and fabricated. An accurate control model of MR damperis also established. Meanwhile, the influence of geometric nonlinearity on modeling anddynamics for both passive and semi-active suspension systems is analyzed via thetheory of rigid multi-body dynamics and numerical simulations. The main contributionsof the dissertation include the following.(1) A novel design of MR damper for Macpherson suspension is proposed in thefoundation of summary and analysis of the present automobile damper. On the basis ofmodified Bingham plastic model (BPM), the equations of the damping force and thedynamic range are formulated for the proposed MR damper. A multi-objectiveintegrated optimal platform using modeFRONTIER is constructed to find the paretooptimal front of the design problem of the MR damper. The optimal platform isintegrated on the Matlab and ANSYS softwares. The genetic algorithm is applied toimprove the solutions and linear dependency and response surface analysis are appliedto determine piston geometric quantities.(2) MR damper is fabricated in terms of the design and the piston geometricquantities. The MTS testing system is used to test the force-displacement, force-velocityand force-temperature characteristics of the MR damper adopted in this study. Thechange rules of the theoretical damping force with the tested damping force are compared, the main cause of the error is analyzed and an accurate control model of theMR damper is also established.(3) The vehicle model with ADAMS/Car is also set up based on the theory of rigidmulti-body dynamics and dynamic model with geometric nonlinearity is deduced usingdisplacement matrix method. The influence of geometric nonlinearity on performanceof passive suspension systems is analyzed and coinciding conclusion is obtainedthrough these methods.(4) Skyhook controller, fuzzy logic controller and sliding mode controller aredesigned respectively based on the dynamic model of MR suspension system withgeometric nonlinearity and the influence of geometric nonlinearity on performance ofsemi-active suspension system is analyzed via numerical simulations. Finally, throughthe reasonable compensation, error of the response of the suspension due to suspensionmodel simplification can be reduced.