Hull Structure Vibration Response Of Ultra Large Ore Carrier

As a complex thin-shell structure,the ship is always subject to external excitations such as the main engine and propeller during sea navigation.With the hull vibration,it may cause discomfort for the crew on board,or affect operation of marine equipment and structural fatigue damage.The ultra large ore carrier is a new product spawned by the national economy in recent years,and the research on its vibration characteristics is still in initial stage.This paper choose the 400,000 dead weight ton ore carrier with the largest tonnage in the world today as the research object of the vibration response,and it will offer the vibration result on ultra lager ore carrier.This paper focuses on excitation,hull natural frequency,and vibration response to study the vibration response of ultra large ore carrier.The following three aspects are mainly studied:(1)The empirical formula method and the model test method are used to analyze the propeller and main engine’s excitied force;(2)The research on the natural frequency of the hull adopts the whole ship finite element analysis method and the empirical formula method respectively;(3)Base on the vibration response of the whole ship finite element method,it was verified by the navigation test results;(4)Others,how to reduce the vibration of the main engine have been studied.The research results show as below:(1)The traditional empirical formula method is still applicable to the estimation of the propeller excitation force of the ultra large ore carrier on the basic design stage,but the remaining margin is large.An improved empirical formula is proposed through research in this paper.This empirical formula can improve the accuracy of the calculation results by about 10%;(2)In terms of hull natural frequency,the traditional empirical formula is no longer applicable to ultra large ore carrier,and the empirical formula needs to be revised.Through research,the ship type of ultra large ore carrier’s vibration correction coefficient,the revised empirical formula can improve about 30% accuracy of the calculation results;(3)The navigation test measurement results show that the vibration response prediction results of the ultra large ore carrier by the whole hull finite element method are reliable;(4)The results of the research on the vibration response of the main engine transverse bracing show that increasing the main engine transverse bracing can effectively reduce the hull vibration response level.