The study of the stacking sequence parameters on critical speed of hybrid composite rotor with experimental and numerical analysis

Composite rotors can be widely used in industries related to rotating machinery due to their lightness and suitable mechanical properties. Investigating the vibration of the rotating composite shaft is essential for proper performance. In this paper, the dynamic behavior of a hybrid composite rotor is studied with experimental and numerical methods. For this purpose, a 28 layers hollow hybrid composite shaft (HCS) with continuously extended fiber reinforcement consisting of carbon/epoxy and glass/epoxy layers with an asymmetrical stacking sequence is modeled and built using the filament winding method. The kinetic energy and strain potential energy of the HCS are calculated considering the modified equivalent modulus beam theory. The governing equations of the HCS are derived using Lagrange's equations. The first three natural frequencies of the HCS are extracted in the free-free state performing the modal analysis test. The results of the numerical solution obtained from the HCS simulation in finite element software and the results extracted from solving the equations by coding using MATLAB script are compared with the natural frequencies of the modal analysis test and validation is done. Then, the experimental test of the hybrid composite rotor with two aluminum disks symmetrical with respect to bearings is performed, and the run-up/coast-down diagram is extracted. The hybrid composite rotor is simulated in ANSYS software and its Campbell diagram is obtained. The critical speeds derived from the simulation are compared with the experimental test, and the correctness of the results is confirmed. Finally, the effect of the stacking sequence and the arrangement of layers using carbon/epoxy and glass/epoxy of the rotating HCS is studied on forward and backward whirling frequencies and critical speeds. By changing the arrangement and proper stacking sequence of the HCS, the critical speeds can be increased, and the resonance of the composite rotor can be avoided.