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Ultrasonic technologies have been widely used in nondestructive and noninvasive testing applications in industry. In this paper, a study on novel nondestructive corrosion detection mechanism with fiber optic photoacoustic ultrasound generator is conducted. The presented corrosion detection mechanism features compact device size (ideal for embedded optical fiber applications), non-contact approach, stable performance, and high spatial resolution. The principle of ultrasonic corrosion detection is introduced in the first section. The experimental procedure for simulation and acceleration of the sample corrosion by using the electrochemical process is also presented. Three steel reinforced rebar samples were prepared with different corrosion rates. The rebar samples were characterized to demonstrate that our mechanism is an effective tool in detecting the corrosion level of steel rebar samples. [ABSTRACT FROM AUTHOR]

Photoacoustic generation using an optical fiber is a promising approach to meet the challenges in most advanced ultrasonic non-destructive testing (NDT) applications. The energy-absorption layer coated on the fiber, endface plays an important role in converting the laser energy into heat and exciting the acoustic wave. The selection of the absorption material and the optimization of the structure dimension are the keys for achieving high energy-conversion efficiency. A 2D-axisymmetric finite element analysis (FEA) model was established to simulate the photoacoustic generation process using a newly developed absorption material, polydimethylsiloxane/gold nanoparticle (PDMS/Au NPs) nanocomposites, with different thicknesses and laser pulse durations. The experimental results obtained using a similar set-up show a similar trend predicted by this FEA simulation. The FEA results provide practical clues to the design of the fiber-optic photoacoustic generator. [ABSTRACT FROM AUTHOR]