Hydroelastic Behaviors of Artificial Islands in Waves

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Floating aiport is currently a unique prototype of the floating artficial island. Popular design in Japan of floating airports is very thin configuration we call a mat-type. In our research we developed a theoretiocal method to predict accurately the hydroelastic behaviors of mat-type floating airports at sea.1.We modelled the body as a sheet of membrane with small but finite magnitude of bending rigidity. This modelling is legitimate because the depth of the mat-type floating airports is very small relatively to the horizontal dimensions ; length will be several kilometers but depth will be several meters. Naturally the bending rigidity is very small and the body will be considered as a membrane rather than a rigid structure.A boundar value problem on the elevation of the water surface and the membrane was derived by implementing this assumption. We treated with the elongated form (mathematically infinitely long) of the mambrane in waves at oblique incidence angle and in deep or shallow water depth. The boundary value problem was derived and solved with considering the membrane as a quasi water surface. This idea is useful in understanding physics of the vibration of the membrane in water waves. Numerical computation becomes extremely simple and its validity is so reliable when the water depth is shallow and linear shllow water theory is applied.2.Planar configuration of the floating airports is not so simply long rectangular in reality. More numerically involved method is inevitable for predicting its behabiors and designing a real airport. A boundary integral equation method was developed for mathematically analyzing waves-elastic-body interaction of complicated configuration. A efficient scheme was devised for solving equations of extremely large number of panels on huge structure surface. This scheme was validated on our semi-analytical solution by the method developed in 1 for simpler geometry.