Composite propeller blades experience significant flow-induced deformations, so coupled simulations of fluid and structure are needed for design optimization and failure prognostics. A comprehensive modelling of the mixer propeller and tidal-turbine blades are discussed within this research work. An extensive CFD, FEM, failure prognostic and bi-directional FSI simulations of layered composite blade are performed. In the last section of the thesis, a novel application of FSI simulation technique involving large deformations and anisotropic property of composite materials are presented briefly.