Study On Vibration Character Of Coupled Beam And Shell Structure

Under the action of propeller exciting force,the vibration of shafting and shell coupled structure is the research focus of underwater structure vibration problems.The vibration study of propulsion shafting and thin shell have separately received a great deal of attention,When the two structure are coupled together,there is less literature available on the topic.In this article,Established the analysis model of shafting,shell and shafting-shell coupled structure based on the approach which the different propeller exciting force transfers in actual physical conditions,and researches its vibration characteristics.The research contents are described as follows:Because of existing analytical methods can not solve the vibration of three dimensional multispan-beams structure,the article used improved Fourier series method to establish the beams coupled model which has arbitrary couple angle and arbitrary boundary conditions based on the Euler Bernoulli beam theory.Used the Rayleigh-Ritz method to derive the vibration theoretical.In the deduction process,The arbitrary couple angles just change the angle between local coordinates and the global coordinates of the beam,and the arbitrary different boundary conditions can accomplish by changing the stiffness of boundary spring,without a new solving process.Compared with the results of ANSYS to verify the correctness of the application of improved Fourier series method.Based on the beam coupled model,an analysis model of propulsion shafting is established,and the propeller is simplified as a quality effect on the shaft.It analysis the natural vibration and vibration response characteristics of the propulsion shafting.A dynamic model of the cylindrical shell with arbitrary boundaries is established.An improved Fourier series method is used to describe the displacement function of cylindrical shell,the equivalent energy method is used to derive the characteristic function.Based on the analysis model of cylindrical shell and propulsion shafting,established the shafting and shell coupled structure model,the junction between shafting and shell by spring group.and analysis vibration characteristics of coupled structure.By comparing with results of ANSYS to verify the correctness of this method.Finally,An experimental model of shafting-shell coupled structure is build,the modal test and vibration response test is used to detect the vibration characteristic of theexperimental modal.And further test the correct calculation method in the article by comparing the measured results with the results of this article.