Research On Numerical Simulation Methods For Evaluation Standards Of Ship Vibration

The ship vibration problem has been always quite a forward thing in the field of ship design.With the evaluation standards of ship vibration constantly updated,research about the corresponding numerical simulation methods have also been a hot spot.Furthermore,more and more attention from the ship owners and shipbuilding divisions are paid to the dynamic characteristic of vibration comfort for luxury cruise ships.Under such a background,based on three different versions of vibration standards,numerical simulation methods for evaluation standards were studied thoroughly.The main contents are as follows:(1)Specific content and evaluation methods of the three vibration standards were elaborated,and technical differences among the vibration standards were analyzed from three aspects: theory system,actual measurement and existing deficiency.(2)Based on different standards,evaluation values considering weighting for typical vibration signals and measured signals on ship were calculated using numerical methods of time domain and frequency domain analysis.When processing data,influences of different numerical parameters on the vibration evaluation value were explored.And then numerical solutions of the two methods were compared with the theoretical solution.(3)Motivation types and corresponding numerical processing methods for ship were analyzed systematically.As for harmonic excitation,two kinds of numerical simulation calculation procedures of vibration evaluation were built,which were applied to a practical case.In addition,the influence of the exciting force phase and distance on vibration value was studied.As for random excitation,the numerical simulation calculation procedure based on ISO 6954:2000 were built for stationary random excitation,which finally was verified by the method of comparing experiment results and simulation results.(4)For calculation of a bulk carrier,mixed finite element model was established firstly,dynamic response predictions for the ship stern and superstructure then were made using two kinds of calculation methods.Next,vibration evaluations were respectively made according to three standards.And at the same time,these data for evaluation were utilized fully to analyze the stringency of these three standards using dimensionless ratio.