Dynamic modal prediction and experimental study of thin-walled workpiece removal based on perturbation method

Because of the removal of the material, the material quality and stiffness matrix of the thin-walled parts will be directly changed and the dynamic characteristics will be significantly changed in the aviation thin-walled parts of the NC machine. When the structural parameters caused by the removal process frequently change slightly, it is necessary to solve the generalized feature problem, by using the classical method to obtain the dynamic characteristics repeatedly or the measured mode. However, it is clear that these methods are time consuming, labor intensive, and are not suitable for efficient prediction of dynamic modes. The method of matrix perturbation is proposed in order to solve the natural modal of the modified thin-walled structure. The finite element method is used to analyze the free vibration of the thin-walled structured blades. Based on the frequency, stiffness matrix, mass array, and vibration data which were extracted from the analysis results, the natural frequency of the modified structural parameters is calculated by the matrix perturbation method; then, the calculated results are compared with the finite element calculation results as well as the measured results. These results show that the process of applying the matrix perturbation method to modify the natural mode is effective, reliable, and time saving in the dynamic mode prediction of thin-walled NC machine, which lays the foundation for the establishment of three-dimensional stability domain. Finally, it can also provide theoretical basis for the resonance suppression of milling process by analyzing the evolutional rule of thin-walled part milling.