Vibration Characteristic Analysis And Vibration Reduction Research Of Trawler Shaft

Trawler is a kind of representative mainstream vessel of fishery ship.Compared with ordinary fishing boats,the trawler has different sailing and working conditions,complex shafting structure and easy to cause power failure.The safety,comfort,reliability and stability of the four major performance indexes of the trawler are closely related to the vibration characteristics of the ship power output shafting.Dynamic characteristics of shafting are also important basis for fault analysis and prediction and fault diagnosis.Therefore,it is of great significance to study the vibration performance of trawler shafting for the overall optimization design of trawler and the normal operation of equipment.To reduce the influence of the vibration of the trawler shafting mainly by improving the stiffness and mass of the shafting,and then to reduce the structural amplitude.In this paper,based on theoretical analysis,simulation calculation and experimental comparison,vibration of trawler shafting and structural optimization scheme are studied.First,the theory of transverse vibration and transverse and longitudinal coupling vibration of trawler shafting is analyzed and introduced.Then,through the modal simulation calculation of the trawler shaft system by ANSYS,the transverse vibration and the transverse and longitudinal coupling vibration are compared in the analysis results.Two conclusions can be drawn from the comparison results.First,it is necessary to consider the coupling factors in the analysis of lateral vibration.Second,it is necessary to consider the effect of transverse and longitudinal coupling on the overall vibration of shafting in the third mode.Then,a corresponding experimental platform was set up for the subject of this study,and a set of experimental trawler shafting platform was constructed.The shafting natural frequency testing experiment could be carried out through Kistler’s corresponding acceleration sensor,data acquisition system and force hammer.The measured experimental data were analyzed by using the improved Hilbert yellow transform(HHT)in MATLAB.In data analysis,vibration information graphs of different aspects,such as spectrum diagram,instantaneous frequency diagram,phase frequency diagram,etc.Based on the comparison and analysis of the above finite element algorithm and experimental results,it can be shown that the ANSYS modal simulation is effective in analyzing the shaft system of this kind of trawler.Next,the vibration characteristics of the trawler shafting are analyzed through ANSYS.Then the conclusion is drawn directly based on the simulationresults.In the research and analysis,the effects of gyro stiffness effect and stress rigidization on the mode are emphasized.It is found that the influence of gyroscope effect on the natural frequency of trawler shafting is positive precession and reverse precession.In addition,the influence of different order states on the stiffness of shafting is different.The hydrophilic effect of propeller in operation is equivalent to the harmonic response analysis of external excitation by empirical formula.It is concluded that not all external excitation is destructive to shafting vibration,To a large extent,the water excitation has the effect of damping on propeller.Based on the analysis of vibration characteristics of shafting,the influence of some main parameters is analyzed and discussed.Then the vibration reduction measures of the trawler shaft system and the corresponding optimization scheme are put forward.The main parameters such as diameter of tail shaft middle section,bearing distance of shaft system and propeller blade are adjusted.Then the optimal vibration analysis results are obtained through simulation experiments.Through structural optimization,Shafting exhibits the characteristics of decreasing amplitude,increasing relative structural stiffness,and not being very sensitive to external influencing factors.Through the study in this paper,the dynamic performance of the trawler shaft system is improved.Make the fishing boats basically meet the expected vibration reduction,It can also provide theoretical reference for later optimization design and fault diagnosis of such trawler shafting.