Ultrasonic wave based structural health monitoring (SHM) is an innovative method for nondestructive detection and an
area of growing interest. This is due to high demands for wireless detection in the field of structural engineering. Through
optically exciting and detecting ultrasonic waves, electrical wire connections can be avoided, and non-contact SHM can
be achieved. With the combination of piezoelectric transducer (PZT) (which possesses high heat resistance) and the noncontact
detection, this system has a broad range of applications, even in extreme conditions. This paper reports an all-optically
driven SHM system. The resonant frequencies of the PZT transducers are sensitive to a variety of structural
damages. Experimental results have verified the feasibility of the all-optically driven SHM system.
Ultrasonic temperature measurements have been developed and widely applied in non-contact temperature tests in many industries. However, using optical fibers to build ultrasound generators are novel. This paper reports this new fiber optic ultrasonic system based on the generator of gold nanoparticles/polydimethylsiloxane (PDMS) composites. The optical acoustic system was designed to test the change of temperature on the aluminum plate and the temperature of the torch in the air. This paper explores the relationship between the ultrasonic transmission and the change of temperature. From the experimental results, the trend of ultrasonic speed was different in the aluminum plate and air with the change of temperature. Since the system can measure the average temperature of the transmission path, it will have significant influence on simulating the temperature distribution.
Ultrasound generation from an optical fiber, based on the photoacoustic principle, could have broad applications, such as
ultrasound nondestructive test (NDT) and biomedical ultrasound imaging. There are many advantages of these fiber-optic
ultrasonic transducers, such as small size, light weight, ease of use, and immunity to electromagnetic interference.
This paper will demonstrate a novel structure which the ultrasound signal is generated on the sidewall of the fiber. Two
experimental configurations of the fiber-optic sidewall ultrasonic transducer are discussed. One is that a photoacoustic
material is directly coated on the sidewall of the optical fiber. The other one is that the photoacoustic material is directly
coated on an aluminum plate and the sidewall fiber is buried in the material. By using this novel sidewall ultrasound
generator, we can effectively generate ultrasound signal at multiple, particular locations along one fiber.
Fiber optic acoustic generators have generated a lot of interest due to its great potential in many applications including nondestructive tests. This paper reports four acoustic generation configurations. All the configurations are based on gold nanoparticles/polydimethylsiloxane (PDMS) composites. Since gold nanoparticles have high absorption efficiency to optical energy and PDMS has a high coefficient of thermal expansion, the composites can transfer optical energy to ultrasonic waves with high conversion efficiency. The strength and bandwidth of ultrasonic waves generated by the composites can be changed by different designs and structures of the composites. This paper explores the relation between the structure of fiber optic acoustic generators and the profile of generated ultrasonic waves. Experimental results also demonstrated that four ultrasonic generation configurations have similar features of ultrasonic transmission on a steel plate, which is important for future choices of ultrasonic receivers.
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