A Study Of The Static-Dynamic Characteristics And Control For The Marine Propulsion Shafting

Marine propulsion shafting is one of the most essential parts of the power plant, if thequality of design and installation is poor or the shafting alignment results are undesirable, thenormal operation of shafting will be affected. The propulsion shafting is subjected to thevarious dynamic factors when it is running, including propeller loads, hull deformation,lubricate oil force and so on. For a special ship, shock loads such as contractile explosion,underwater non-contact explosion and the bounce-back force caused by weapon’s emissionmay effect to the propulsion shafting. With the improvement of the ship power and themaximization of Propulsion shafting, the shafting alignment and vibration problem becomemore severe recently, so the researches on the alignment and vibration performance ofpropulsion shafting, and the study on vibration control has importantly valuable significance.This paper takes a large marine propulsion shafting as the research object, and built theshafting calculation model with the finite element method. By this model, the following isresearched and studied in the propulsion shafting optimum alignment calculation, shaftingnatural frequencies and vibration model calculation, steady response under of the propellerincentive, transient response and shafting vibration control under of the impact load and soon.(1) Having calculating optimum alignment on the elastic-bearing propulsion shafting,analyzing the dynamic influential factors on shafting alignment.We found out that thecalculation result on elastic-bearing model and rear bracket bearing model which having twofulcrums can reflect the actual shaft better, influence of propeller loads and hull deformationon analyzing forces of bearing is more. Those factors should be considered in shaftingalignment.(2) After calculating the shafting natural frequencies and vibration model of the propulsion shafting, and mainly analyzes several factors that affect the natural frequencies.We found out that the rear bracket bearing supports state, stern tube bearing stiffness andbearing contacting length effect the natural frequencies in a great degree; additional watermass decreased the vibrations of natural frequencies.(3) We found that impact load makes propeller displacement greatly by the research ofthe vibration response under of propeller incentive and impact load. It’s likely to endanger thesafe operation of the propeller, so it’s necessary to control the shaft vibration.(4) Considering the characteristics of the MR damper, the semi active control strategywas proposed. Using the finite element simulation method, analyzing and comparison of theshafting control effect under the impact load of different control state. The result proves thatMR dampers have good damping effect in the vibration control.