Gold nanocomposites-based photoacoustic multi-modal ultrasonic response coupling numerical simulation for...

Photoacoustic (PA) technologies have found increasing application in ultrasonic monitoring, particularly for evaluating micro-cracks in metallic materials. In this study, we investigate the underlying mechanism of ultrasound generation via the PA effect and propose a comprehensive multi-modal ultrasonic analysis framework aimed at the quantitative detection of surface-breaking micro-cracks in HRB400 crescent ribbed rebar. To enhance the efficiency of PA conversion, a gold polydimethylsiloxane nanocomposite (Au-PDMS) was synthesized through a straightforward one-pot method, and broadband ultrasonic waves were excited using a 532 nm nanosecond pulsed laser. Drawing from experimental insights into corrosion-induced damage, we constructed a numerical simulation model to track crack development over time. A series of crack evolution scenarios were simulated by incrementally increasing crack depth in 500 μm steps. The resulting ultrasonic responses were examined in both time and frequency domains to extract key features. Based on these characteristics, a set of multi-parameter predictive mathematical models was established. The results underscore the sensitivity and robustness of the proposed multi-modal ultrasonic approach in capturing crack progression, offering a promising tool for advanced non-destructive evaluation (NDE) of rebar structural integrity.