Research On Shafting Vibration Of Large Vessel Based On The Bearing Support State

The hull deformation will change relative position of bearing chock, thereby change the support state of bearing. At present the research on shafting vibration is based on the hull as rigid body without deformation, but hull deformation is one of the most important influences on propulsion shafting vibration, which can’t be ignored. Therefore studying shaft vibration frequency and amplitude based on hull deformation have a broader and more practical value.This paper research the shaft vibration on the factors of effective contact length of stern tube bearing, bearing stiffness and bearing relative position, based on reading a lot of data about shaft vibration both at home and abroad. Finally compiling the ship shaft lateral vibration calculation software. The main content of the paper summarized is as following:(1) For studying the effective contact length of stern tube bearing’s influence on its natural vibration frequency and loads, using the software AN SYS to establish a finite element model of ship shafting, then analysis the change of shaft vibration and bearing load through adjusting the effective contact length of the aft and the fore stern tube bearing. The results show that:as the effective contact length of the stern tube bearing decreases, the natural frequency of shaft vibration correspondingly reduces. Besides, the load on bearing contact areas increases significantly with the effective contact length of the stern tube bearing decreases.(2) For studying the bearing support stiffness’s influences on shaft vibration frequency, calculate the bearing oil-film stiffness in Matlab according to the theory of fluid lubrication. Then coupling the oil-film stiffness with hull stiffness, explore the factors of bearing support stiffness and hull stiffness to shaft vibration. The calculation results show that:as the stiffness of the stern tube bearing increases, the natural frequency of shaft vibration correspondingly increase. However the hull stiffness has little influence on shaft vibration. (3) For studying the position of bearing’s influence on shaft vibration caused by hull deformation, taking bulk carrier as calculation example, by FEM, this paper presents the calculation procedure and methods for shafting lateral vibration, which takes shafting center line vertical relative deformation into consideration. The results show that:under different condition, shafting center line vertical relative deformation makes significant influence on shafting lateral vibration natural frequency.(4) Finally use windows Server2008as platform and VB9.0as development tool, designed interface and compiled calculation program. Using the transfer matrix method calculated the frequency and made shape of shaft lateral vibration. Developing ship propulsion shaft lateral vibration calculation software which has independent intellectual property rights.