Study On Vibration Performance Of Water-lubricated Damping Stern Bearing

The stern bearing is an important part of the ship shafting,and its vibration condition directly affects ship's stealth,security performance and staff's physical and mental health,so the research on damping stern bearing in reducing the vibration and noise of ship shafting has important theoretical significance and engineering application value.In order to study the vibration performance of damping stern bearing,the finite element simulation analysis of water lubricated damping stern bearings was carried out using ANSYS-Workbench software.The results of modal analysis,harmonic response and transient response of both damping bearing and general bearing are compared,and the influences of different damping layers were considered.Based on the simulation analysis,experiment was conducted to study the similarities and differences between the vibration performance of both damping bearing and general bearing,the correlation between theoretical analysis and experimental results,and the reliability of theoretical analysis.The main research work and results are as follows:(1)Establish three-dimensional model of the bearings and calculate the free modal and constrained modal of the general bearing and the damping bearings within the modal modular in Workbench.Analysis the influence of the structural and material parameters of damping layer on the bearing's constrained modal.The results show that the free modal frequencies and constrained modal of the damping bearing are lower than those of the general bearing.The deformations of the general bearing's free modal and constrained modal shapes are all in the liners,but partial maximum deformations of the damping bearing's modal shapes are in the damping layer.The first six order constrained modal frequencies of the damping bearing become larger when longer,thinner or harder damping layer is used within a certain range.(2)On the basis of modal analysis,the harmonic response module is used to calculate the response difference between the damping bearing and the general bearing under sine excitation force of different frequency,and analysis the influence of the structural and material parameters of damping layer on the bearing's harmonic response.The results show that both general bearing and the damping bearing have a harmonic response peak at a same frequency,which corresponds to the twelfth order mode of the general bearing and the second order mode of the damping bearing,respectively.The peak amplitude of harmonic response becomes larger when longer or harder damping layer is used in a certain range.When the thickness of the damping layer is 12 mm,the displacement response peak value of the bearing is larger than that of other thickness considered.(3)On the basis of modal analysis,the transient response module is used to calculate the response of both damping bearing and general bearing when the bearings' plates are subjected to external excitation force,and analysis the influence of the structural and material parameters of damping layer on the bearing's transient response.The results show that the maximum displacement response of the damping bearing is smaller and the response time is shorter than those of the general bearing.The decrease of the thickness and the hardness of the damping layer in a certain range can reduce the maximum displacement response of the damping bearing in transient excitation and shorten the decay time.The decay time is shorter when the length of damping layer is longer in a certain range,but the maximum displacement response is not necessarily smaller.(4)Both general bearing and the damping bearing are respectively installed on the test bench,and the vertical and horizontal acceleration amplitude of the bearings is measured during the operation.The results show that,when the shaft's rotating speed is 80~200 r/min,the loading pressure is 0.2~0.4 MPa,the damping bearing has a certain effect on the vibration attenuation in the frequency range of 0~800 Hz.