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• A rubbing rotor model with multiple wide-chord blades is developed. • The localized rub-impact phenomenon of blades by synchronous forces is found. • The asynchronous force makes all blades rub in turn with a phase difference Δ φ = 2 π / Ω ± ω N b . • The swing motion intensifies steady tip-rub, but weakens unstable tip-rub. • The gyroscopic effect weakens the swing motion and the stable rub-impact fault. In turbo-machinery, wide-chord blades are widely used due to the advantages of improving fan efficiency and aerodynamic performance. The rotor with multiple wide-chord blades is spaced from the outer casing. The small clearance may cause rub-impact fault between wide-chord blades and the casing, which induces different damage severity or the destruction of the whole machine. Numerical simulation is necessary to analyze this kind of rub-impact fault, but the solution process becomes complicated because of the coupling of geometric nonlinearity, local vibrations of wide-chord blades and gyroscopic motion of the rotor. This paper develops a rubbing rotor model with multiple wide-chord blades considering the gyroscopic effect and geometric nonlinearity induced by rub-impact. Based on the rub-impact model established for wide-chord blades, the high-order nonlinear governing equations of the bladed rotor are derived. Vibration responses are solved, and a series of dynamic characteristic analysis is carried out. The results reveal that high-order nonlinearity has a little effort on vibrations during slight rub-impact. But with the increase of transverse deformation induced by severe tip-rub, its influence cannot be ignored. Besides, localized rub-impact phenomenon of blades induced by external synchronous forces is found. Instead, external asynchronous force makes all blades rub, one after another along the circumferential direction of the disk, and there is a phase difference Δ φ = 2 π / Ω ± ω N b between the vibration responses of adjacent blades. Then, we found that the swing motion intensifies the difference of transverse deformations along the chord direction of wide-chord blades with tip-rub, which may induce the edge failures. Also, the swing motion intensifies the steady rub-impact fault. It could weaken or eliminate its divergence and instability when the rotor with multiple wide-chord blades is unstable. The gyroscopic effect could weaken the swing motion, and then weakens the stable rub-impact fault. [ABSTRACT FROM AUTHOR]

Abstract: This paper uses a semi-analytical approach to investigate the frequency response, bifurcation, and chaos of a rotating large deflection plate subjected to rub-induced non-linear vibrations. The general equations are coupled with the lateral displacement and two in-plane stretch variables and were derived using Hamilton's principle with consideration given to the centrifugal stiffening effect. The accuracy of the solution method is demonstrated through a comparison of modal characteristics found in the literature. Special attention is given to the influence of friction coefficients, the rubbing force amplitude and the contact load time on rub-induced non-linear vibrations. The results show that the frictional effect in tip-rub is the main source of rub-induced non-linear vibrations for the rotating large deflection plate. Increases in the rubbing force amplitude and the contact load time produce more non-linear effects such as more paths to chaos and a jump phenomenon, and intensify the vibration of the system. [Copyright &y& Elsevier]