Study Of Natural Frequency And Vibration Response On Very Large Crude Oil Carrier

With ship built orients to a large-scale size and with the application of high strength steel,the stiffness of hull structure reduces,it result in ship hull vibration problem more and more obvious.Excessive vibration may influence the normal operation of shipping,induce ship structure fatigue failure,and have an adverse effect on the crew’s the health.Therefore,the vibration characteristics must be accurately predicted in the various design stage,and then find the existing problems and solutions,so as to avoid resonance and make the ship meet the requirements of low vibration and noise.In this paper,the natural frequency and vibration response on very large crude oil is studied.The main studied content as below:Firstly,this paper briefly introduces the vibration theory and the main excitation sources of the ship,analyzes the influence of instantaneous excitation and continuous excitation on the ship vibration,and focuses on the analysis of the vibration sources,characteristics of excitation force,calculation method and control strategy that cause the steady-state vibration of the ship.Secondly,in this paper,the finite element method is used to calculate and analyze the natural vibration frequency and vibration response of the hull.From a theoretical point of view,several natural frequencies and natural formations of the total vibration of the hull are obtained so as to grasp the basic dynamic characteristics of the ship.Vibration response analysis is made for propeller and main engine excitation that causes steady-state vibration of the ship,aiming at predicting the vibration response of the ship at the design stage.Thirdly,the vibration intensity of the ship was obtained through vibration exciting test and real ship sea trial measurement,and was compared with the theoretical calculation results and criteria to verify the correctness of the theoretical calculation method.Finally,through the engineering practice method,three optimization schemes different from the original ship are put forward for the severe vibration of the ship,and theoretical calculation and vibration measurement of the real ship are carried out.The vibration effects of the three schemes are compared,and the optimal scheme is finally obtained and applied to the subsequent type ships.