Pulsed-laser ultrasound generation in graphite/epoxy plate

A laser-based ultrasonic technique using a pulsed laser to stimulate ultras onic waves in fiber-reinforced graphite/epoxy composite plate is the subjec t of investigation. For convenience, the material is chosen to be homogeneo us and transversely isotropic. The study is strictly limited to the laser p ower regimes that are suitable for nondestructive evaluation. An elastodyna mic methodology is presented based on an integral formulation in order to d evelop a representation for the dynamic responses in terms of the character istics of the source that originated the motion. This requires the computat ion of the elastodynamic Green's function which represents the displacement field from the idealized synthetic sources localized precisely in both spa ce and time. A two-dimensional numerical analysis utilizing a finite differ ence method for computation of the Green function in a finite plate is deve loped which provides the basis for quantitative nondestructive evaluation o f fiber-reinforced composite materials. Numerical results are presented for the surface displacement at the epicenter. Prediction based on numerical s imulations are compared with experimental results.