Fiber reinforced composite materials have been used in many structural applications varying from swimming pool diving boards to advanced aerospace components. The primary advantage of composites includes a high stiffness to weight ratio which in the past has come at an increased cost. Continued improvements in the development of cost effective manufacturing methods and development of low cost fibers and resin materials have increased the use of composites in infra-structural applications such as buildings, and bridges. As fiber reinforced composites become more widely used, the need for a reliable method to nondestructively characterize the material stiffness properties and identify material defects is becoming critical for ensuring a reliable level of performance.