Vibration Properties Analysis Of 2400t-River-to-sea Bulk Cargo Ship

Ship’s structures are very complex and ship is also a kind of elastic structure which leads that ships often produce vibration when it is sailing normally.Ship hull vibration problems have always been hot and difficult spots on structural engineers’ research for a long time.Ship vibration can cause hull structure fatigue damage,affecting ship strength and reducing ship life.Once a ship produces severe vibration,there will be very serious harmful consequences for itself and its crew,its equipments,and so on.we need to focus on the vibration problems in the ship design phase.This paper is based on the 2400t River-to-Sea bulk cargo ship of Heilongjiang Water Tansport&Planning Institute,referencing national and international ship vibration research methods to analyze the vibration performance in-depth.The ship can sail from river to the sea.The tail and mid-tail areas have obvious vibration phenomenon when it sails from river to the sea,and their vibration levels are also different along with the host engine revolving speed.This paper uses the software MSC.Patran to create the whole ship three dimension finite element model and uses the software Abaqus to analyze and calculate ship hull natural frequencies for checking its frequency storage when it sails in rivers and on the sea under two typical conditions(Full Loading Departure and Ballast Arrival)with added mass.In order to evaluate the ship vibration characteristics much better,this paper analyzes the steady forced vibration response,respectively calculating the transient response under different host engine revolving speed and when it sails with one propeller and two propellers.By analyzing the vibration performance in-depth,we realized that the ship will vibrate more with one propeller than with two propellers,and that the ship tail did have strong vibration response when it sails from river to the sea.The main reason is that the host engine or propeller’s frequency is equal or similar to one of natural frequencies.So we suggest that this kind of ship should adopt double-propeller when it is sailing,and when the boat sails into the sea,we should pay attention to the choice of the host engine and propeller revolving speed because it needs to meet the requirements of the natural frequency storage of ship hull.