Study On Hydrodynamic Performance And Strength Of VLFS

Ocean is of great significance to the development of marine countries.In the ocean far away from the land,it is necessary and urgent to provide a reliable offshore base as the place for exploitation and storage of marine energy,as the research place for marine scientific research and as the military base of strategic significance.It is urgent to carry out the research and development of very large floating structure.Based on the theory of three dimensional potential flow,the theory of short term wave prediction and the theory of the direct strength calculation of finite element,a series of related hydrodynamic performance and strength analysis are carried out in this paper by the ANSYS/AQWA.First,the hydrodynamic response of the floating structure with single module is calculated by AQWA-LINE,and the transfer function of motion response and the transfer function of wave load on cross sections are obtained when the single module floating structure in the regular wave with unit wave amplitude.Then the laws between the motion response,the wave load and the wave frequency and direction of the floating structure with single module are obtainedSecondly,the short term prediction of wave load is carried out,and the parameters of sea condition which are suitable for the calculation and analysis of floating structure with single module strength are obtained.Then the strength calculation in the corresponding sea condition is carried out,and the stress distribution characteristics of the joined single-module floating structure in the actual sea condition are obtained.The stress concentration produced at the joint of the strut and the bottom floating structure can be improved by changing the structural form of connection.Thirdly,the hydrodynamic response of the joined multi-module floating structure is calculated,and the motion response characteristics of the very large floating structure are obtained.The motion response curve of each module is approximately consistent with the single module.Based on this,the frequency domain calculation in the actual sea condition is carried out,and the peak of motion response at different degrees of freedom is obtained.The laws between the form of joint,number of module and the motion response of the joined multi-module floating structure are obtained that the peak value of the overall motion response of the very large floating structure increases with the increase of the number of module,and the connector with universal joint can be conducive to reduce the motion response of the very large floating structure.Finally,load on connectors is carried out,and the laws between the joint form,module number and the connector are obtained.These conclusions of the joined multi-module floating structure can be used as a reference for further research on the very large floating structure.