Research On Longitudinal Vibration Suppression Of Ship Shaftting Based On Rubber-clad-particle Damping

The suppression of longitudinal vibration of the ship’s shafting system has always been a research hotspot,and its goal is to explore suitable methods or techniques to suppress harmful vibration to the maximum extent.Due to the complexity of the ship’s shafting structure and space,the level of shafting longitudinal vibration suppression is far from achieving the desired effect,and new methods,measures and technologies for solving shafting longitudinal vibration are still needed to be developed.Particle damping technology is a new type of damping technology,which has achieved excellent results in the field of vibration control,but there have been few reports on its application in ship shafting longitudinal vibration suppression.In this paper,particle damping technology is used to suppress the shafting longitudinal vibration.Through discrete element simulation and simulation test,the mechanism of longitudinal damping suppression of particle damping and the influence of related parameters on longitudinal damping are studied.Main research contents and conclusions are as follows:（1）The particle characteristics and damping characteristics are analyzed,and the rubber-clad steel composite particles are determined as the research object.The discrete element method was used for the simulation calculation of particle damping,and the contact model and time step were determined during the simulation calculation.A high-speed camera test was performed,and the particle recovery coefficient was obtained.The damping coefficient of the particle was obtained.（2）The particle damping characteristics and energy loss simulation calculations were performed,and the influence of the particle motion state,mechanical properties,damping characteristics,vibration environment,motion response,and damper structure on the energy loss of the system was analyzed.At the same time,the movement of the particle group in the shaft cavity is simulated by simulation,and the change of the velocity distribution and the force chain structure of the particle group during the movement are analyzed.（3）The L₈（2~7）orthogonal table is used to arrange two-level test points.Through the quadratic regression orthogonal combination design,a regression model of particle damping characteristics is established to study the change law of system energy consumption.Quantitative analysis was performed,and the response curve was drawn according to the regression equation.The results showed that the particle size,mass filling ratio,and axial length of the cavity had different degrees of interaction.The nonlinear regression theory and method were used to optimize the obtained regression model,and the optimal parameter combination scheme for particle damping design was obtained.（4）Experimental studies of particle vibration reduction ratios under non-rotating and rotating conditions were performed,and the movement of particles were investigated in actual experiments.The influence law of particle size,mass filling ratio,axial length of the cavity,the frequency and displacement of the excitation on longitudinal vibration suppression of system were revealed.The results show that rotating speed,mass filling ratio and axial length of the cavity have a significant effect on the vibration reduction ratio of the system,and the particle size,excitation frequency and amplitude have more general effects on the vibration reduction effect of the system.The motion state of the particles will affect the collision and friction inside the particle group,between the particles and the wall surface,and it is an important factor affecting the vibration energy consumption and longitudinal vibration suppression of the system.