Identification On Inertia Parameter Of Commercial Vehicle Cab And Method Research

Commercial vehicle cab suspension system design is not only the importantfactors that affect the cab security, but also the key to influence ride comfort, in thedesign of suspension system, on the one hand, should consider suspension position,suspension method, system parameters such as stiffness, damping of each component,on the other hand, must get the rigid body inertia parameters of cab, such as the cabquality, centroid position, the moment of inertia and product of inertia, then researcha kind of commercial vehicle cab recognition method has important practicalsignificance for accurate identification of inertia parameters and improve the drivingcomfort.Through the study of frequency response function curves which are obtained bymodal experiment, found that between the system highest order rigid body modes andfirst order elastic modal exist a horizontal curve, namely quality admittance line, thecurve not only contains rigid body parameters of the system, but also is not affectedby the elastic mode, then based on the quality admittance line, obtain the system rigidbody inertia parameters according to the rigid body dynamics, and regard thisidentification method of rigid body inertia parameters as the residual admittancemethod. In order to verify the reliability of residual admittance method, put a gearboxshell as the research object and design a verification experiments, based oncalculating modal and test modal, using CAD/CAE calculation method and residualadmittance method to identify gearbox shell of rigid body inertia parametersrespectively, through comparing calculation value and experimental value to verifythe reliability of residual admittance method to identify the rigid body inertiaparameters. Finally, apply the method to the commercial vehicle cab, and accordingto the structure characteristics of the cab design a test plan, then identify its rigid bodyinertia parameters.The result of the gearbox shell verification experiment is as follows: for themodal parameters, the frequencies maximum deviation of calculating modal and testmodal is3.98%, appear in the4th order elastic modal, and the first order elasticmodal relative deviation is1.11%, difference is only2.6Hz; For the inertial parameters, the maximum deviation of gearbox shell centroid coordinates appears inthe Y direction, the maximum deviation is9.1%, but the difference is only0.7mm,the maximum deviation of principal moments of inertia is5.42%, the maximum angleof the principal axis of inertia in the same direction is1.96, the angles of the resttwo inertial axis are all about1. In short, according to the data of modal parametersand inertia parameters, the software calculated value and test value keep a highdegree of consistency, then the residual admittance method is reliable to recognizesystem rigid body inertia parameters. In addition, from the result of rigid body inertiaparameters based on residual admittance method, the test value and finite elementcalculation value of principal moments of inertia keep a high degree of consistency,centroid position and principal axis of inertia is in accordance with the structurecharacteristics and mass distribution of the cab.