Dynamic Analysis And Vibration Sensing Of Thin-wall Annular Workpiece

During the machining thin-wall components, such as compressor disks in aircraft engines is easily affected by the clamping force, cutting force and other factors. The distributed deformation and vibration of the work piece renders to poor precision and quality. Therefore, knowledge of the dynamic characteristics' evolution of the work pieces prior to or during the machining process is important and it provides the possibility to choose appropriate values for the process parameters. The modal analysis is a practical method to study the dynamic properties of components under impulse excitation. Through theoretical analysis and vibration experiment can identify the structure parameters of the modal frequency and damping ratio etc. This paper have studied the vibration characteristics by the method of theoretical analysis, finite element simulation and experimental verificationUsing the classical plate theory to establish the dynamic model of annular plate, and formulated the method of boundary value problem. In the viscous damping model, the equivalent damping of multi degree of freedom system under the principle of superposition is obtained. The frequency and mode data of the thin-wall plate model are obtained by modal analysis and finite element analysis(FEA), the effectiveness experimental modal analysis system is verified through the comparison of the theoretical and experimental results. In order to study the effects of different fixture and dynamic characteristics during processing, this paper analyzed the influence of diameter ration and thickness of the workpiece on modal frequency using finite element and vibration experiment.The vibration displacement of workpiece can obtain by using an eddy-current sensor. Through design the bandpass filter can separate the vibration waveform of each modal. Then according to the free vibration attenuation method to fit the modal damping ratio of each order frequency. Using the modal damping ratio can simulate the dynamic response under pulse excitation by finite element analysis. Compare to the experimental result of different sensor placement, it has provided the theory basis for sensing configuration design.