Modal identification of cylindrical shell using circumference reduction method

Abstract

For precision improvement of the noise prediction, the dynamic characteristics of structures need to be verified. This paper focuses on modal identification of the cylindrical shell structures. In such structures, vibration modes with complicated shapes exist densely. And structures made of composite material have high damping characteristics. Therefore, the experimental modal parameter extraction is somewhat difficult task. In this study, we investigate modal parameter identification method which is able to be applied to such structures. We propose circumference reduction method based on basis function, and non-linear least squares approach of curve-fitting. The circumference reduction method has an effect of reduction of modal density, so the difficulty of identification is improved. Using a simple cylindrical shell structure, the results of proposed method and FEM modal analysis are compared and evaluated. Furthermore, as an example of a real structure, the modal property of an automobile tire is identified. It is verified that the modal property of cylindrical shell structure can be identified effectively using proposed method.