| The development of large-scale ships has caused some ship shafting to become longer,which makes the accuracy of the ship’s shafting installation parameters particularly important.Common shafting installation parameters include bearing elevation,flange offset,number of bolts or pre-tightening force,eccentric mass of the propeller,etc.All these will have a direct impact on the shaft whirling vibration and become an important factor affecting the stability and safety of the ship’s shafting.In this paper,the axis of a container ship is taken as the research object,and the influence of installation parameters such as bearings,connecting flanges,connecting bolts,and propellers on the whirling vibration of the shaft system is studied using finite element analysis.The main research contents and conclusions are as follows:（1）The effect of bearing stiffness changes caused by bearing elevation on the shafting whirling vibration.Firstly,the influence relationship between the bearing mounting height and stiffness was analyzed,and then the influence of each bearing stiffness change on the shafting whirling vibration was studied.The results show that:raising the bearing elevation will increase the bearing stiffness;changing the bearing stiffness will obviously change the natural frequency of the shaft system’s whirling vibration,but different bearings have different effects on the natural frequency;The common amplitude value of the low-order whirl vibration of the shaft system is significantly higher than that of the higher order,increasing the bearing stiffness will reduce the vibration amplitude of the shaft system.Stern bearing stiffness changes have a greater impact on vibration amplitude than intermediate bearings（2）Effect of flange connection offset on whirling vibration.The influence of flange mounting offset on the whirling vibration of the shafting was studied.The results show that: the natural frequency of the shaft system will decrease with the increase of the flange offset.The distribution of resonance points at different positions of the shaft system and the magnitude of the common amplitude are different.Increasing the flange offset increases the common amplitude value of the shafting,which affects the loworder common amplitude value more than the high-order,but it has no obvious effect on the distribution of resonance points.（3）Influence of the number of connecting bolts on the whirling vibration of the shafting.The influence of the number of connecting bolts on the whirling vibration of the shafting was studied.The results show that: increasing the number of bolts will increase the low-order natural frequency of the shaft system,and reduce the high-order natural frequency,but have no obvious effect on vibration mode;increasing the number of bolts will reduce the common amplitude of the shaft system,but the effect of reducing the vibration amplitude decreases as the number of bolts increases.（4）Effect of eccentric of propeller installation on shaft whirling vibration.Keeping the eccentricity constant,by applying different eccentric masses on the propeller disc surface,the effect of the eccentric mass of the propeller on the shafting whirling vibration was studied.The results show that the amplitude of the shafting whirling vibration increases with the increase of the eccentric mass of the propeller,and the magnitude of the eccentricity and the amplitude of the shafting whirling vibration are linear and proportional. |
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