Stress Measurement of a Pressurized Vessel Using Candle Soot Nanocomposite Based Photoacoustic Excitation

摘要

This article aims to develop a pressure sensing method by utilizing both a contacting active sensor and a non-contactinglaser ultrasound transmitter. An overloaded stress in an industrial pressure tank such as a nuclear reactor may cause acatastrophic explosion; thus, it is essential to monitor the mechanical stress in a reliable manner for the structural safety.Among many different types of stress sensing methods, ultrasound sensing has been attractive due to its non-invasivemeasurement feature. For the recent decades, subsurface longitudinal (SSL) ultrasonic wave has been widely used sinceit is not only less dependent on the internal medium and the surface condition, but also has the fastest wave speedwithout wave distortion. In our work, laser source and Aluminum nitride (AlN) wafer are used to generate and to receiveSSL ultrasonic waves, respectively. In order to increase the photoacoustic efficacy, a composite of carbon-sootnanoparticles (CSNP) and polydimethylsiloxane (PDMS) was attached onto the intermediate wedge at the transmitterside. The photoacoustic experiment results demonstrate a reasonable linear relationship between the stress level and thetime-of-flight variation of the propagated wave signal.