A Study On Method Of Calculation And Measurement For Performance Of Torsional Vibration Absorber

Installing an absorber on the crankshaft is a common method to reduce the torsionalvibration of engine. Torsional vibration absorbers(TVA) are widely used in passenger carscrankshaft damping because of the simple structure and low cost.The torsional stiffness and damping of rubber ring are closely related to the excitationfrequency, compression ratio and deformation of rubber ring. Kelvin Voigt, Maxwell,fractional derivative mechanic models are widely applied in the study of the dynamicmechanical properties of rubber. In this paper a special fixture is designed and used formeasuring static and dynamic performance of a rubber shear specimen under differentcompression ratios. Three constructive models for characterizing the rubber viscous properties(Kelvin Voigt constructive model, the Maxwell constructive model and the fractionalderivative constructive model) are described, and the method for obtaining the modelparameters in the three constructive models are developed using the measured dynamicperformance of a rubber shear specimen. The natural frequency of a TVA is calculated usingthe three models to characterize the rubber ring of the TVA, and the calculated frequencies arecompared with the measurement. It is demonstrated that the natural frequency of the TVAcalculated by the Kelvin Voigt model is constant when the excitation amplitude is increased,which is inconsistent with the measured data. The calculated natural frequency using theMaxwell and the fractional derivative model to describe the rubber ring of a TVA is theexcitation amplitude dependent, which is consist with the trend of measured data. But therelative errors between the calculation using Maxwell model and the measurement under thelarge amplitude excitation are large, and is not be accepted in engineering application. Thenatural frequency estimated from the fractional derivative model agrees well with themeasured data for different excitation amplitudes, and the relative error between thecalculation and measurement is less than7%.In order to prevent the axially slide and around the axis slide of inertia ring and hub ofTVA, the maximum axially slip force and slip torque around the axis must larger than thesafety threshold. The maximum axially slip force and slip torque around the axis are influenced by the size of TVA, elastic force of the rubber ring, maximum static frictioncoefficient of contact surface of rubber ring and hub. Mooney Rivlin material model wasestablished to calculate elastic force of the rubber ring. The maximum static frictioncoefficient of contact surface of rubber ring and hub was calculated by combination ofmeasurement and Abaqus software.Torsional vibration model of crankshaft with a TVA was established, a TVA matchingmethod by genetic algorithm was recommended. A TVA matching measurement for an inlinefour-cylinder engine was held, the results show that the TVA matching method by geneticalgorithm is scientific and effective.