During vibrothermographic experimental testing of damaged composite plates, frequency dependent heat generation phenomena were observed. Local hot spots were formed around imperfection areas especially delaminations. Heat generation was also found to relate to the crack size. In order to explain the above observed phenomena, the dynamic behavior of undamaged and damaged composite plates was studied over a broad frequency range. The analysis was carried out using the finite element method based on the concepts of the three dimensional theory of anisotropic elasticity. Delaminations were modeled, and the local crack resonance’ was justified. Two NDE methods namely, Vibrothermography and SPATE were used to verify the numerical predictions. Experiments performed for both undamaged and damaged specimens, and good correlation between theory and testing was achieved. / Master of Science