Determination of elastic constants of laminated cylindrical shells by means of elastic waves

Laminated cylindrical structures have been widely used in model industry, from aerospace, nuclear to automobile industries. Effective use of laminated cylindrical shells relies on a precise knowledge of the material property of the constituent materials; hence their property evaluation has been one of the focuses of research. It is obviously valuable to develop a reliable method to non destructively measure the properties of composites. Utilizing elastic waves for such a purpose can be promising, as we have a reasonable good knowledge about elastic waves propagating in cylindrical structures. Numerical models of laminated cylindrical shells have been developed to solve forward problems that relate the elastic constants to elastic wave fields. Thus if a set of reasonably accurate experimentally measured response data is available, elastic constants of laminated shells may be identified by solving an inverse problem properly formulated. A procedure is proposed to inversely determine the elastic constants of laminated shells from dynamic displacement responses obtained at only one receiving point on the outer surface of laminated cylindrical shells. An analytical numerical method is used for forward computation that relates the elastic constants to the displacement responses. A real parameter coded micro genetic algorithm is proposed based on the existing binary coded uniform micro genetic algorithm, and used in the inversion procedure and its effectiveness to the present type of applications is proven. The robustness of the procedure to the effect of measurement noise is also investigated. Numerical simulations are performed and satisfactory identification results have shown the effectiveness of the present procedure as well as its robustness to the given noise added to the input displacement responses. Refs. 3 (author)