Efficient tool for designing 2D phased arrays in lamb waves imaging of isotropic structures

Ultrasonic phased arrays have a considerable application potential for structural health monitoring (SHM) of planar structures. 2D topologies are required to obtain unequivocal damage localization in these applications. Since array performance depends, among other factors, on its topology, there is a demand for robust and numerically efficient tools for arrays design. To deal with this problem we propose a method based on frequency-dependent structure transfer function that can deal with multi-modal and dispersive nature of Lamb waves as well as with the arbitrary shape of the excitation bursts. The proposed method is validated using an accurate numerical model of waves propagation. Finally, an efficient experimental method is proposed employing virtual array implemented by means of scanning laser vibrometer for sensing the Lamb waves in multiple points corresponding to the locations of the 2D array elements. In this way the performance of various array topologies can be evaluated experimentally in the reception mode without the need for a physical prototype.