Nonlinear and Linear Phenomenon Investigation of Coupled Vibration of a Multi-Disc Rotor Based on Multi-Mistuned Blade Length or Multi-Disordered Straggle Angle Blades

This study used the finite element method (FEM) and assumed mode method (AMM) to refine the disk-transverse, blade-bending, and shaft-torsion coupling vibration phenomenon of a multi-disc system with multi-mistuned or multi-disordered blades. The authors explore and compare the change regulations of the natural frequencies and mode shapes in the rotor system. Numerical calculation results show that the number of mistuned or disorder blades, as well as their symmetry, will affect the natural frequencies. In a quantitative case, the authors set blade (1) at 10% mistune, and blade (2) has mistune from -10% to +10%. The frequencies of 1a(11) and 1b(12) to 1b(15) modes are unchanged in the length error of blade (2) variation. The frequencies of 1b(11) (SDB) modes decrease from 100.63 Hz to 67.50 Hz, with a blade (2) length error increasing from -10% to 10%. The rotation effect is also explored, and it is found that the mistuned effect becomes complex and unstable.