Abstract:  In order to reduce the deflective vibration of the membranous disc of the metal diaphragm coupling with spherical plain bearings during operation, the vibration characteristics of the flexible diaphragm coupling were investigated. Firstly, for the purpose of improving the accuracy of finite element modal analysis, the equivalent contact finite element model of the metal diaphragm coupling was established according to the characteristics of finite element analysis in dealing with contact problems. Then, the vibration characteristics of the metal diaphragm coupling with and without spherical plain bearings and the effect of spherical plain bearings on the axial and radial stiffness were studied by the finite element method. Finally, the test rig was constructed using the LMS test system to analyze the vibration characteristics of the metal diaphragm coupling with and without spherical plain bearings under two ends fixed and free state, and the experimental result was compared to the simulation. The research results show that the equivalent contact region method can be used to simulate the contact characteristics of the metal diaphragm coupling under the test conditions with high precision and calculate each order modal parameter and each order modal shape, the calculation error is kept within 5%. The spherical plain bearing installed at the position of the diaphragm can increase axial stiffness and protect the diaphragm, while it has little influence on radial stiffness. The results of this study provide a support for the structure design and optimization of the metal diaphragm coupling with spherical plain bearings.
Key words: metal diaphragm coupling with joint bearing; equivalent contact area method; polarization of coupling diaphragm;natural frequency; modal test; vibration characteristics; contact characteristics; vibration testing system