Difference Between FBG and PZT Acoustic Emission Sensor
Acoustic emission detecting technology has been applied in many areas of structural health monitoring as a nondestructive method. The conventional piezoelectric sensor is widely used, but it is bulky and cannot be used in extreme environments such as heav
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Abstract Acoustic emission detecting technology has been applied in many areas of structural health monitoring as a nondestructive method. The conventional piezoelectric sensor is widely used, but it is bulky and cannot be used in extreme environments such as heavy electromagnetic interference, extreme temperature, high pressure, and strong corrosion. Fiber Bragg grating is made from silicon dioxide, small size (diameter of only 250 μm), can be embedded into the measured object, and has advantages of anti-electromagnetic interference and corrosion resistance. In the paper, firstly, the sensing principle of interaction between acoustic emission wave and fiber Bragg grating acoustic emission sensor is introduced, and demodulating approach is presented. Secondly, based on fiber Bragg grating acoustic emission sensor, a feedback acoustic emission detecting system is built to avoid the temperature interference. Finally, the direction sensitivity and frequency response of fiber Bragg grating acoustic emission sensor are studied and compared with piezoelectric sensor, which could provide the basis for practical application of fiber Bragg grating acoustic emission detecting technology. Key words Acoustic emission · Fiber Bragg grating · Difference
1 Introduction Acoustic emission (AE) detection is a nondestructive testing of defects in the material structure. Since the discovery of acoustic emission in the 1950s, acoustic emission detecting technology has been successfully used in aerospace, machinery manufacture, petrochemical industry, and other fields [1]. However, conventional piezoelectric sensor (PZT) is the most widespread sensor in the current acoustic emission detection, which belongs to electrical sensor and is inevitably susceptible D. Xia · P. Wei (*) · C. Li School of Instrumentation Science and Opto-Electronics Engineering, Beihang University, Beijing, China e-mail: [email protected] © Springer Nature Switzerland AG 2019 G. Shen et al. (eds.), Advances in Acoustic Emission Technology, Springer Proceedings in Physics 218, https://doi.org/10.1007/978-3-030-12111-2_3
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to electromagnetic interference, strong corrosion, making sensor not working properly [2]. The fiber-optic is a silica, small sized, and lightweight, has high sensitivity, and most importantly can overcome the disadvantages of PZT AE sensor, which make the fiber-optic acoustic emission detecting technology come into being. The fiber-optic detecting technology is divided into a variety of detecting principles. Fiber-optic Fabry-Perot cavity technology has a wide measurement range and stable system [3], but the Fabry-Perot cavity is difficult to make, the reproducibility is low, and the cost is high. Though the sensitivity of the fiber-optic ring acoustic emission technology is higher [4, 5], there are inevitably electrical devices no matter whether homodyne demodulation or heterodyne demodulation, which is not conductive to all-fiber network system [6–8]. In addition, the size of fiber-optic ring is large. Fiber Bragg grating (FBG) aco
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