Torsional Vibration Calculation And Analysis For Ice Class Ship

There are two parts included in TVC,free vibration calculation and forced vibration calculation.The calculation methods for free vibration calculation are Holzer method,transfer matrix method and matrix eigenvalue method etc.There are energy method,transfer matrix method and system matrix method for forced vibration calculation in tradition.By the widely application of computer,the transfer matrix method and system matrix method used more instead of energy method.They both are the method of frequency domain.The periodic excitation was dealt by Fourier transform into series of harmonic excitation.The result of each harmonic excitation was solved respectively.The valve of arctic channel shows gradually and development of oil gas and mineral resources in arctic with global warming,there is big opportunity for ice class ship.Many ship Owners requires the ship with ice navigation ability and with ice class notation.But for the ice navigation,the propeller may be impact by ice block,which results in big torque response in shaft system and it is difficult to give the torque response.The above traditional calculation method in frequency domain can't solve this non-steady problem.It is necessary to find a new method in time domain.The literature for shaft torsional vibration was collected both in and aboard.The calculating method and calculation process were discussed in the thesis.On this basis,the mass-elastic model was studied.Then the system matrix method for torsional vibration was discussed.The un-damped differential equation was solved for free vibration and the differential equation was transform into linear equation for forced vibration.The total response was get by vector synthesis of all harmonic excitations,which make good consistency with the calculation result of MDT software.For the ice impact calculation,the ice torque was calculated according to the Class rules and the ice torque were gave for typical cases.The merits and drawbacks between Rung-Kutta method and successive integration method were described.The Newmark-? method,which is unconditional stability,was used to built the program and to calculate the three cases given by Class rules.And last the ice impactsimulation by AMESim was made,which get a similar result to the Newmark-? method.