Research On Vibration Characteristic For Composite Blade With Damages

Composite blades are used in almost all modern helicopters. For the application value in engineering, it has become more and more important to analyze the vibration of these blades.It is compared between the experiments and the finite element software MSC.Patran/Nastran in this dissertation. First, the finite element dynamic analysis models of no-damaged and damaged composite laminates are established, and the natural frequencies are calculated with one end of the models clamped. The results show that the simulation method matches the experiments. On this basis, no-damaged and damaged finite element dynamic models of sandwich plates are established using the sandwich theory. In the case of four sides simply supported, the natural frequencies are calculated. Contrasting the analytical method based on the Zig-Zag deformation assumption and the Mindlin first order shear theory, the results show the sufficient agreement between the two methods. Thereby, the validity of solving this problem by MSC.Patran/Nastran is verified. The finite element model of a composite blade is established by Patran, and the vibration characteristic is analyzed with one end of the blade completely clamped. The results show the model is feasible for application in engineering. A small-scale delamination will not impact the whole blade mode sufficiently, and a greater impact over the natural frequency of the blade is made by the perforation comparing to the delamination.