Research On The Influence Of The Alignment State On The Lateral Vibration Of The Ship Propulsion Shafting

The alignment is one of the important factors affecting the vibration of the ship propulsion shafting(hereinafter referred to as the shafting).However,the current research on shafting alignment mainly starts from the perspective of statics.The shafting was laid in a certain state to ensure that the bearing load and the stress of each shaft section are within the allowable range,to ensure that the strength of the shafting meets the requirements of safe operation.However,the influence of the alignment on the lateral vibration of the shaft system is rarely considered.With the increasing requirements of ship vibration and noise,it is very necessary to carry out research on the influence of the alignment on shafting vibration.This thesis took the shafting as the research object,and studied the influence of the alignment on the shafting lateral displacement response through numerical simulation and test methods,and studied the influence of the alignment on the acceleration response of the shaft bearing seat through test methods.The main research contents and conclusions are as follows:(1)A finite element model of the shafting was established,and the finite element method of rotor dynamics was used to calculate the lateral displacement response of the shafting under different alignments.The results showed that as the shafting misalignment excitation increases with the elevation of the front stern bearing,the amplitude of the 2 frequency multiplication component in the lateral displacement response of the shafting near the rear bearing gradually increased.(2)On the ship propulsion shafting test bench,a mass disk was applied to the stern of the shafting to simulate the cantilever load,and the shaft alignment test at different speeds was carried out.The lateral displacement response of the shafting was analyzed.The results showed that during the increase of the front stern bearing elevation,the amplitude of the 2 frequency multiplication component of the shafting lateral displacement response near the rear stern bearing continued to increase,the changing law was consistent at different speeds.(3)On the ship propulsion shafting test bench,the shaft alignment test at different speeds with and without torque was carried out,through the cantilever load of the mass disc applied to the stern part of the shafting.And the acceleration response of the rear bearing seat was analyzed.The results showed that under the non-torque condition,the shafting alignment gradually deteriorated with the increase of the front stern bearing elevation,the amplitudes of the fundamental frequency and 2 frequency multiplication component in the acceleration response of the rear stern bearing seat gradually increased,the changing law was consistent at different speeds.Under torque conditions,the shafting alignment gradually improved as the elevation of the front stern bearing increases,and the fundamental frequency and 2 frequency multiplication components in the acceleration response of the stern bearing seat gradually decreased,the changing law was consistent at different speeds.