Research On Vibration Characteristics Of Marine Engine-shaft-propeller Of Sailing Ship

With the process of large ships, ship propulsion shafting constantly develop in the direction toward the large-scale, in order to ensure the strength of the shaft, so that the shaft can work Continuously, security and stability, and transmission output torque and thrust. Shafting vibration is an important factor in causing damage to the shaft. During the voyage the status of shipwill be affected bywaves, On one hand causing the hull deformation, on the other hand causing the hull sway. Hull deformation is delivered to the bearings, and change the support statusof shaft, to of the hull sway will attach additional inertial force to the shaft, two changes will affect the vibration modes of shafting.This paper isbased on the shaft of a sailing ship,it described the basic principles of shafting vibration theory and analysis the ship sway response with finite element method, shafting natural vibration frequency, harmonic response of the shaft by the dynamic excitation. The main contents of the paper include the following aspects:(1)) Study the state of the ship sway affected by waves. Analysised the ship’s roll, pitch and heave response amplitude operatorin detail, according to the passing relationship between wave spectrum and the spectrum response of the hull S(ψ)=(RAO)2Sw(ψ)(where S(ψ) spectrum responseof the hull sway, Sw(ψ) P-M wave spectrum) to get the hull response.(2)Studied the natural vibration theory of lateral vibration,the vertical vibration, torsional vibration in the shaft’sfree statues, and getthe natural frequency of the shafting lateral vibration, vertical vibration and torsional vibration and its’modes.(3)Study the response of the hull sway, after the conversion to the sine function will be applied to the shaft respectively, then simulate the harmonic response, and calculate the harmonic response of the propeller pulsating thrust. After analysis, proposed measures to reduce vibration.Through the harmonic response analysis we can obtain that the maximum transverse vibrationdeformation appears when the heave excitationfrequency is equal to its first-order transverse vibration natural frequency,the maximum torsional vibrationdeformation appears when the heaveexcitationfrequency is equal to its first-order torsional vibration natural frequency,and longitudinal vibration deformation is almost zero.