Study On The Time And Frequency Domain Parameter Identification Method For Damping Composite Structure

Parameter identification technique is the most commonly used test method invibration engineering. For complex strctures whose danymic characteristic isdifficultly determined by the theoretical method, we can get the characteristic byparameter identification technique easily. Parameter identification belongs to theinverse problem in structural dynamics, it involes many fields widely. Especially inthe field of aerospace, the strctures become big and complex, most of thesestructures has the characteristics of low frequency, dense frequency and smalldamping; if considering large deformation and materials nonlinear, it involves thenonlinear parameter identification problems; these problems have brought greatdifficulty for structrue parameter identificaiton. Therefore, developping a newparameter identification method to solve the above problems is necessary.In this paper, we propose a parameter identification method which combinesthe time and frequency domain parameter identification of the substructure and thesubstructure modal synthesis technique. We use AMD+HT method to identify themodal parameter of the substrcture, then we get the modal parameter of the overallstructure by the modal synthesis technique; we also identify the system parameter ofthe simple nonlinear system by the time and frequency domain method. The mainworks are as follows.Firstly, we develop the time and frequency modal identification method of thelinear system. By introducing the analytical modal decomposition(AMD) method,we construct the AMD+HT method for the identification of the structures having thethe characteristics of low frequency, dense frequency and small damping. Then wemake some modal parameter identification examples for multi-degree of freedomdiscrete system and a continuous structure system by AMD+HT method.Secondly, we solve and analyze the single-degree of freedom nonliner systemby the wavelet transform method and the KB method, then construct the parameteridentification method for the nonlinear system containing arbitrary nonlineardamping and nonlinear stiffness.Thirdly, we develop the damping modal synthesis technique. By introducingthe proportional viscous damping model, we build the damping fixed interfacemodal synthesis method. And the new method is applied to analyze the modalcharacteristice for the damping beam and the damping plate.Finally, we combine the AMD+HT method with the damping synthesistechnique to identify the modal parameter of the building shear model. By thisexample, the accuracy and the effectiveness of the new method are validated.