Dynamic modelling and analysis of the shaft system connected by the metal disc coupling with crack: Theory and experiment

Metal disc couplings have been widely used in aviation and navigation. However, the metal disc may experience crack failure under long-term and high-speed working conditions. To fill the lack of the effect mechanism and operation monitoring of the crack failure of the metal disc, this paper studied the dynamic modelling and analysis of the shaft system connected by the metal disc coupling with the crack. The experimental shaft system connected by the metal disc coupling is constructed, and then its dynamic model is established. The stiffness matrix of the metal disc with the crack is calculated, and the results show that the crack can cause a decrease and asymmetry in the direct stiffness, and introduce cross-coupled stiffness. The decrease in the direct stiffness leads to an increase in the system amplitude. The asymmetry in the direct stiffness leads to the super-harmonic resonance and introduces a clear 2 × component in the system’s acceleration response. The cross-coupled stiffness causes the axial vibration of the system, but it can be ignored. The appearance of a 2 × component in the system’s acceleration response can be regarded as an identification signal for the crack of the metal disc. The established dynamic model’s accuracy and the identification signal’s effectiveness are verified through critical speed and constant speed experiments. The method proposed in this paper can provide theoretical support for the dynamic design and operation monitoring of the metal disc coupling.