Global Vibration Analysis Of Some Bulk Carrier

The ship is a elastomer, when the ship is sailing,the hull will be vibration because of the action of main engine, propeller or other excitement.Minor oscillation is allowable,if the excitation frequency equals the natural frequency of vibration,or the amplitude was excessive,it would give rise to resonance and severe forced vibration to affect the normal voyage of the ship, consequently the global vibration analysis of the ship is necessary.Previously experience formulas is used to calculate the natural frequency of the ship within four nodes,the results meet the actual situation,but the precision drops greatly up wards four nodes. In this paper take a bulk carrier as an object,used finite element method for the vibration of the hull,finite element method is a accurate calculational method to compute the natural frequency of the ship,but it consumes too much time and money.The three dimension finite element model of bulk barrier has been generated in MSC.PATRAN, the NASTRAN has been used in the calculation of the natural frequency under two typical conditions (Coal Loading Dep, Ballast Arrival),the vibration response under the excitation of propeller and main engine will be analyzed,the calculation is resonable,we believe it can guarantee the high quality of it's sister vessel.