Vibration Identihcation Of Engine Inertia Properties And Excitation Force

It has become a vital issue in the process of vehicle development to deal with the enginevibration attenuation and isolation, in order to avoid transmitting excessive engine vibrationwhich influences passengers' comfort and causes fatigue failure of body's components to thebody. The identification of engine's inertia parameters and excitation force is a prerequisitefor vibration attenuation and isolation. At the meantime, the identification of the engineexcitation force requires a previous knowledge of the inertia parameters. Only when theinertia parameters are available, the engine excitation force can be extracted from the cylindersurface vibration.The identification methods of engine inertia parameters and the influence of windowingand additive White Gaussian Noise on the accuracy of amplitude and phase based oninterpolation method are studied, based on the above research, the excitation force isidentified. The main contributions studied in this paper mainly focused on the follows.Firstly, simple direct methods are presented to identify the engine inertia parameters ofthe engine under a free-free condition or with a previous knowledge of elastic mount stiffnessin situ, simulation and experiment results confirm the validity of the presented methods.Secondly, a direct system identification method for engine inertia parameters is presented,which can accurately identify not only the ten inertia parameters but also the system stiffnessand the damp, and the method is validated through both simulating as well as through thetesting of an engine's inertia properties. At last, the paper investigates the influence ofwindowing and additive White Gaussian Noise on the accuracy of amplitude and phase basedon interpolation method. Analytical expression of the estimator variance for amplitude andphase correction is derived, respectively. Simulation results confirm the validity of thepresented analysis.The interpolation method with a Hanning window is applied to the excitation forceidentification, simulation results vilified the accurate amplitude and phase extracted from thevibration by the interpolation method with a Hanning window. Influences on the excitationforce identification are analyzed quantitatively. Through the multi-rigid-body dynamics modelsimulation experiment, the excitation force identification method is confirmed. Based on theinterpolation method with a Hanning window and the identified inertia parameters, apreliminary engine excitation force experiment is carried out.