Investigation On Coupling Analysis Between Floating Structures And Flexible Structral Members

Coupling analysis between floating bodies and flexible structural members is the keycontent to the mechanics for floating structures, and now it has been a focus in ship and oceanengineering field. A package of investigation was conducted for the purpose of seeking theessence behind coupling analysis and making it practical.A boundary integral equation with composite distributed source and dipole wasemployed to solve the potential flow problem in frequency and time domain, combined withfree-surface Green function for infinite water depth. A grids meshing method of boundaryelements (BE) based on finite elements (FE) was presented by considering the feature ofboundary integral equation. By applying the symmetry of Green function and body geometryto computation, the author presented a decomposition method of incident potential, whichcould make a significant reduction of matrix’s dimensions. This method can enable symmetryto be applied to incident potential and diffracted potential, which are with no symmetry inessence. Also, the transmission in computation on symmetry was investigated and theefficiency analysis was made. On the basis of ordinary differential equations (ODE) fortime-domain Green function and its gradients, which were presented by Clement, animproved computation method was given. In this method, an identical equation was derivedfrom the integral representation of Green function, which could help to reduce computationaleffort distinctly. For this reason, only one ODE needs to be solved instead of three.A nonlinear finite element method (FEM) was employed in the dynamic analysis processof flexible structural members. Based on elastic rod theory, this method could take intoaccount the geometry nonlinearity of deformation. Dynamic characteristics of flexiblestructural members were analyzed by sensitivity analysis for several parameters, and theinfluence of some nonlinear factors was investigated.Coupled methods were summarized by computation and argumentation. Coupling modesin frequency and time domain between floating structures and flexible structural memberswere presented. Several methods of coupling parameters determination were presentedcombined with theoretical analysis and engineering practice. Some computation instanceswere given for explanation. Finally, several solutions with practicability to various engineering problems were summarized.