Row-column addressed arrays for nondestructive evaluation applications

Abstract

Row-column addressed (RCA) arrays are 2-D arrays formed by two orthogonal overlapping linear arrays made up of elongated elements. This substantially reduces the number of elements in the 2-D array. Modeled data are used to compare RCA arrays in pulse-echo mode to fully populated 2-D arrays for nondestructive evaluation (NDE) applications and an improved beamforming algorithm based on the total focusing method is tested. Improved beamforming has led to a less than half-wavelength diameter conical bottom hole being successfully detected experimentally using an RCA array, with a maximum signal-to-noise ratio of 17.0 dB (3.s.f). The average difference between the-6-dB drop width and the nominal drill bit diameter when sizing flat bottom holes experimentally using RCA arrays is also improved compared to plane B-scan algorithms from (1.29 ± 0.07) mm to (0.23 ± 0.04) mm. These developments demonstrate the advantages of using RCA arrays over conventional fully populated 2-D arrays and provide a basis for their use, and development, in the field of NDE.