Research And Software Development About Transient Torsional Vibration On Typical Propulsion Shafting Of Ice Ship

In order to obtain the steady-state torsional vibration response in the frequency domain and transient torsional vibration response in the time domain of the propulsion shafting caused by ice impacts:(1)Based on the single blade ice torque excitation defined by the classification society and superposition principle,a polar ship designed with an ice thickness of 1.5m is used as an example to fit the time-domain torque excitation of the ice load for each excitation case of 3~6 blade propellers.Subsequently,the harmonic analysis of the time domain excitation of ice load was carried out,and the dimensionless excitation coefficients for each excitation case and each harmonic of the 3-6 blade propellers were obtained.The discrete lumped parameter equivalent model and system matrix method were used to calculate the steady-state torsional vibration in the frequency domain for propulsion shafting in ice region.Based on this model and method,the flow of steadystate torsional vibration calculation in the frequency domain of propulsion shafting under ice impacts was put forward,which can provide method guidance for calculation of steady-state torsional vibration calculation in the frequency domain of propulsion shafting caused by ice impacts.(2)The classical frequency domain lumped parameter multi-particle model and Newmark-? stepwise integration method was adopted to obtain the time-domain transient torsional vibration response of propulsion shafting subjected to ice impacts.The time-domain transient torsional vibration analysis of typical propulsion shafting in an ice-borne ship excited by an ice-free load was performed to verify the correctness of transient torsional vibration calculation of the propulsion shafting in the time domain using the Newmark-? method under ice loading.The key technologies and influencing factors such as excitation,damping,speed drop of shafting,load limit of main engine,average speed solves,the determination of the phase angle between ice and gas force excitation,and maximum dynamic response amplitude method in transient torsional vibration calculation of propulsion shafting under ice impacts was intensely researched,and the process of transient torsional vibration calculation in the time domain of typical propulsion shafting under ice impacts was put forward,which provides guidance for the time-domain transient torsional vibration calculation of ice ship propulsion shafting.(3)Based on the Visual Basic.NET programming language,a set of torsional vibration calculation software for ice ship typical propulsion shafting is developed with full independent intellectual property rights through mixed programming of Visual Studio and MATLAB.It completely meets the requirement of China Classification Society for plan approval.The Visual Studio platform builds the interface for data input,transmission,storage,results display,and printing.And the core calculation module was written in MATLAB and compiled into a dynamic link library for Visual Studio calls.Among them,the transient torsional vibration response in the time domain was calculated using the unconditionally stable Newmark-? step-by-step integration method,while the way of free vibration calculation and the steady-state torsional vibration response in the frequency domain were calculated using the system matrix method.The calculation of the software was carried out on a low-speed diesel engine propulsion shafting of a bulk carrier calculated by MAN B&W and electric propulsion shafting of a polar carrier calculated by Aker Arctic.The relative error between the test result and the report is within 5%.Software test results show that the method used by the software is stable and reliable,the program is correct,and the calculation results meet the requirements of engineering accuracy.The software,which satisfying the requirements of each computational condition of the propulsion shafting can provide the basis for design calculation,calibration calculation and accident analysis of ship propulsion shafting in ice or ice-free areas,has the advantages of complete functions,strong versatility,friendly interface,simple operation,high accuracy and high speed,and can meet the requirements for each condition.