This article studies the dynamic behavior of a delaminated composite plate using a numerical model and explores the possibility of delamination detection using nonlinear interaction in the delaminated region. A composite plate with three cases of the delamination is first considered using the model via a series of simulated examples. Experiments on simple aluminum plates with and without delamination are then carried out to confirm the existence of the nonlinear interaction between the delaminated layers. The simulated examples are finally compared with earlier published experimental results on composite plates. The article discusses the results and observations of the study of delamination detection in the composite structures.