The proposed thesis is part of the development at CEA LIST of integrated models in the CIVA software platform of expertise in Non Destructive Testing. The thesis precisely aims at extending the models of components inspection by ultrasonic waves, in order to develop by a ray method a complete simulation tool of the ultrasonic response of the specimen geometry. Complete inspection modeling requires simulating echoes from the geometry or structures of the inspected components. The existing ultrasonic field model is based on the ray formalism of geometrical acoustics. The objective of this thesis is to extend this model in order to deal with the diffraction from structures edges and with multiple interactions (specular reflections and diffractions). To model the diffraction from edges, ?uniform corrections? of the Geometrical Theory of Diffraction will be developed. The model will be validated by comparison with experimental results and with simulation results obtained by a finite elements method.