2019 Volume 75 Issue 2 Pages I_41-I_49
In this paper, a novel shape reconstruction method based on the time-reversal technique is presented for the purpose of quantification of the ultrasonic nondestructive testing. First, a forward analysis of 3-D scalar wave scattering by rigid scatterers in an infinite region is solved by using the convolution quadrature time-domain boundary element method (CQBEM), which can produce higher accuracy than conventional time-domain boundary element method (BEM). In the proposed method, the topological sensitivity is used to identify the shape and position of defects in 3-D infinite space, and it is obtained by solving the corresponding adjoint problem of the forward one with the aid of CQBEM for 3-D scalar wave propagation. As numerical examples, some numerical results of shape reconstruction of a scatterer and multi-scatterers in an infinite space using the proposed method are demonstrated. The reconstruction ability of the proposed method is investigated by changing the radiation pattern of ultrasound from a phased array transducer and the number of scatterers, and by comparing the results obtained by the synthetic aperture focusing technique (SAFT).
