Signal Enhancement in Surface Crack Detection with Gas-Coupled Laser Acoustic Detection

Abstract Ultrasonic signal enhancement resulting from constructive interference between direct Rayleigh waves and same reflected by a surface defect is exploited to increase crack identification capabilities of the Gas-Coupled Laser Acoustic Detection (GCLAD) non-contact detection technology. Highlights simulations are provided regarding phenomenon in solid its propagation air, where GCLAD occurs. Experimental campaigns preliminarily performed on bar evidence effect cracks acquired signals. Then, +30% reached plate, implying that defects efficiently scanned moving proximity discontinuity. Since allows monitoring points piece belonging line at once, translation one direction sufficient perform two-dimensional scan, entailing reduction inspection time simple automation interrogation layout compared other traditional or enhancement-based techniques.