Phased Addition Reconstruction in Anisotropic Media

Structural health monitoring of plate like structures, using transducer arrays located suitably on the structure, finds applications in monitoring aerospace structures. These plates are anisotropic, with wave propagation properties varying with direction. Thus any technique for imaging this plate structure needs to take this into account. In this paper, a phased addition reconstruction algorithm, based on SAFT, is described for imaging reflectors (edges, defects) present on the plate structure. The algorithm takes into account the anisotropy in the material and performs phased reconstruction using appropriate dispersion data depending on the direction of reconstruction. The algorithm can also accurately reconstruct defects present in the near field zone of the array, since it takes exact distances into account. The algorithm can also be used to image for any array configuration and also the domain can be subject to any discretization as required. The Single Transmitter Multiple Receiver (STMR) array was chosen for simulations and experimentations due to its advantages. Simulations were also performed for linear array configuration, to demonstrate the applicability of this algorithm for arbitrary array configurations.