Delamination monitoring by the local velocimetry based on the spatio-temporal gradient analysis

In this paper, a novel method of local phase velocimetry based on the spatio-temporal gradient analysis is proposed. The proposed method has an ability to measure the local phase velocity of the zero/sup th/ order anti-symmetric Lamb wave field through the linearity among following four components: a vertical displacement, its vertical velocity, and a pair of out-of-plane shearing strains of the surface. In this study, the computational process in the Lamb wave field near the defects is discussed and their physical meanings are investigated through FDTD-simulations.