Study On Vibration Of Coupled Shafting And Cylindrical Shell Caused By Propeller Longitudinal Exciting Force

The problem that propeller exciting force transfers from shafting, the bearingsupporting to structure and causes structure vibration is the research focus of underwaterstructure vibration problems in recent years. Currently, such problems mostlyconcentrated in the discussion about beams, plates, shells and other structural vibrationmechanisms. But the mechanism of structure coupled vibration research few.This paper has researched the calculation method about the propeller longitudinalexciting force via the propulsion shafting caused of structural vibration. The dynamicalmodel is built. Based on an improved Fourier series method, it has established theLagrange function of the structure, and used Rayleigh-Ritz method or equivalent energymethod to derive the vibration theoretical. Afterwards, the finite element method andexperimental method has used to validate the theoretical algorithm. Are as follows:To set up a dynamic model of the propulsion shafting, The Rayleigh-Ritz method isused to derive the vibration theoretical of shafting. It analyses the natural vibration andvibration response characteristics of the shafting with propeller longitudinal and lateralexciting force. Then it analyses the control effect of the shafting longitudinal.A dynamic model of the cylindrical shell with arbitrary boundaries is established,the equivalent energy method is used to derive the vibration theoretical of shell. Bychanging the spring stiffness at both ends of the cylindrical shell, it analyses the naturalcharacteristics and vibration response characteristics of cylindrical shells with simplysupported, clamped-free, free-free three of boundary conditions.A dynamic model of the coupled shafting and structure is established, the equivalentenergy method and Matrix combination method is used to derive the vibrationtheoretical of coupled structure. It analyses the natural vibration characteristics ofcoupling structure with simply supported boundary. By applying the longitudinalharmonic excitation force to the shafting, it calculates vibration response characteristicsof the coupling structure.An experimental model of coupled shafting and structure is built, it analyses the lawof coupled vibration from the experimental point of view. The natural frequency andmode shape of the structure is obtained by experimental modal analysis method. Afterthat, it obtains the transfer function of the experimental model. By experimental method,it validates the accuracy of the model-building method and theoretical algorithm.