Modelling and vibration evaluations of rotational mistuning-connecting disk-drum coupling structures with partial hard-coating damping treatment

Abstract

Mistuning connections between drums and disks are very common in engineering. However, this point has not been mentioned in previous studies. This work develops discontinuous arc connections with different connecting stiffness to simulate actual mistuning connections by modifying the traditional spring method with continuous distributions. The admission functions are represented by good-convergence orthogonal polynomials. Through considering the rotation-generated gyroscopic and centrifugal effects and utilizing Kirchhoff's plate theory and Sanders’ shell theory, the dynamic model of rotational mistuning-connecting disk-drum coupling structures with partial hard-coating damping treatment (PHDT) is derived through Lagrange equations and verified by utilizing FEA and existing literature, in which the partial-coating model is more suitable for practical vibration suppression than the existing whole coating model. Moreover, further mistuned vibration evaluations show that the mistuning connections induce the change of mode order, frequency division, and vibration localization. The veering phenomenon caused by mistuning is also revealed, and the modal coupling and dominant mode exchange during veering are explained by the change of mode shape and MAC. Furthermore, the mistuning will also seriously affect the key information (critical speeds, instability positions, and veering positions) in Campbell diagrams. The present model provides key technical references for the vibration prediction, connection fault diagnosis, and coating parameter optimization of rotational disk-drum coupling structures with PHDT.