Reconstruction of Defects in a Circular Annulus Using Time-Domain Inverse Scattering Method by Circumferential Guided Waves

In this paper, we consider an elastic two-dimensional annulus which represents a cross section of pipeline. The mode expansion method is used to calculate the transient response when the excitation is applied on the surface. Numerical examples and FEM simulations are given and they are in good agreement. Based on previous procedure, the time-domain Green’s functions are obtained. After that, an inverse scattering method is proposed by use of boundary integral equation about the scattered wave field in time domain. With introduction of Born approximation, an inverse scattering scheme can be formulated to reconstruct the locations and shapes of cracks and inner cavities. Results show that as long as time domain data are enough, a receiver array can obtain locations and rough images of cavities within the structure.