In-plane elastic property characterization in composite plates

This article presents a method to deduce the in-plane elastic properties of multilayered composite plates. Drawing on a synthetic-aperture technique developed for the elucidation of materials properties in air-coupled ultrasonics, this new method exploits the high elastic anisotropy of composite materials to permit an accurate measurement of directional in-plane stiffness. It is found that comparisons of experimental measurements with plate stiffnesses calculated on the basis of lamination theory agree to within several percent for uniaxial and biaxial laminates and to within 10 percent for quasi-isotropic laminates. It is further shown that the method is largely insensitive to transducer deployment angle within a range related to the transducer beamwidth.