Study On Vibration Reduction Of The Aft Of 1000DWT Product Oil-tanker

As the ship develops toward large-scale and rapidness,the power of main engines also increases.On the premise of meeting the structural strength,the ship structure stiffness decreases and the probability of harmful vibration to the hull increases.To the product oil tanker,excessive vibration can cause fatigue damage to the hull structure and shorten the life of the ship;Excessive vibration affects the normal operation environment of the equipments and installations on the ship and increases risks of navigation.Excessive vibration also affects the health of the crew,causes fatigue and is harmful to their normal work and life.With the modification and upgrading of Ship Vibration Evaluation Standards.The ship vibration prediction,anti-vibration and noise reduction has attracted attentions of the shipbuilding industry and becomes difficulties of the ship owner and ship builder.First of all,the paper refers to the vibration status of No.5 1000 DWT Class-one Product Oil-tanker built by Dalian Songliao Shipyard as a case,and makes contrast to the 1000 DWT Class-one Product Oil-tanker built by some shipyard of Lushun.Though the oil-tankers use identical drawing and shape,however different building environments,the vibration results are largely different.Through the measurements of the two oil tankers,comparing vibration test points distribution conditions,analyze the position and features where vibration arises.Secondly,through citing related theories,analyze the causes of vibration.Through analysis and removal,basically discover the possible reasons of vibration arising from the respect of principles.Focusing on the propeller shock excitation,diesel engine shock excitation,wave shock excitation,etc.,discuss the causes of vibration.Thirdly,through reading drawings and standards,and applying the equation for calculation,infer out that the clearance between the stern line and propeller has not meet the requirements of ship design standards for No.5 1000 DWT Oil-tanker,which causes the side flow of propeller decrease.The induction force of the propeller causes the vibration of the stern.Meanwhile,through the modification and check to the upper deck of the stern,make the modification plan to the structure and deck,which can suppress the vibration effectively.Through the measurements of vibration,the results show that the technically modification reduces the harmful vibration effectively.Through the typical anti-vibration case,provide beneficial reference to the same type vessels for vibration reduction measures and methods.