WAVE FIELD PRODUCED IN A COMPOSITE LAMINATE BY A CONCENTRATED SURFACE FORCE A. K. Mal and S.-S. Lih Department of Mechanical, Aerospace and Nuclear Engineering University of California, Los Angeles, CA 90024 INTRODUCTION With the increasing use of advanced composites in a variety of modern applications, it has become necessary to employ reliable and effective nondestructive evaluation (NDE) methods to determine the integrity and service ability of structural composites. The use of ultrasonic techniques involving guided waves and contact type transducers can provide powerful characterization methods for composites. However, the wave phenomena associated with these methods are, in general, far more complex and less weIl understood than those associated with conventional techniques, based on longitudinal waves. Realization of the fuIl potential of these newer techniques will require a better understanding of the quantitative features of the wave phenomena than is available at present. In this paper we consider the problem of the response of a unidrectional composite plate to a concentrated dynamic surface load. To the authors' knowledge, the theoretical solution to the point load problem has not appeared in the literature to date, although the corresponding problem for the isotropie case has been solved [1, 2]. Two-dimensional models involving line loads on plates have been considered by Green and Baylis [3] among others. The formal solution of the three dimensional problem consisting of multilayered, angle-ply laminate subjected to spatially periodic distributed surface loads has been given by Mal [4]. The composite is modeled as a transversely isotropie and dissipative medium as in [5] and a classical integral transform technique coupled with a matrix method is used to derive a formal solution of the problem in terms of wavenumber integrals in the frequency domain. The integrals involved in the spatial inverse transform are evaluated by me ans of an adaptive integration scheme and the resulting frequency spectra are inverted by FFT. Numerical results for the surface displacements are presented for several locations and for different time histories of the source. Review 0/ Progress in Quantitative Nondestructive EvaluaJion. Vol. 11 Edite<! by D.O. Thompson and D.E. Chimenti, Plenum Press, New York, 1992 137