| Author: | Tsang, Kwok On |
| Title: | Low cost and efficient method in cracks detection of piezoelectric materials |
| Advisors: | Cheung, Nobert (EE) |
| Degree: | M.Sc. |
| Year: | 2018 |
| Subject: | Hong Kong Polytechnic University -- Dissertations Piezoelectric ceramics Ceramics -- Defects |
| Department: | Faculty of Engineering |
| Pages: | xi, 74 pages : color illustrations |
| Language: | English |
| Abstract: | Piezoelectric ceramics PZT has been widely used in transducer as a sensor or actuator and many works have been reported on the characterizations of the materials properties. Piezoelectric ceramics could be bonded on the surface of certain device to form a thin patch functional unit. One major problem is that the crystal before bonding is in good characteristics, but will suffered from unexpected structural change, damage or even potential cracks created inside the crystal that could not be easily revealed during the manufacturing process of the PZT on the host devices. Hence, it is difficult to maintain the normal operation of the crystal after long hours of work that could lead to the mal-function of the device. This is especially important to implantable biomedical devices like artificial cardiac pacemaker that requires reliable operation and warning message should be sent to the patient earlier before failing to operate. There are many researches focused on the materials characteristics in the studying of the PZT, but there are seldom works proposed to differentiate good and bad piezoelectric crystals in low cost and efficient methods. So far, a number of ways are proposed to the crack detection, but they are either expensive or complicated, and the results are not guaranteed. In this work, simulation work based on the Van Dyke Model to investigate the possible outcomes due to the existence of cracks by varying the components values inside the equivalent circuit. From the experimental results of impedance measurements on the piezoelectric samples, no obvious difference between good and poor qualities samples are observed except the imaginary parts. Therefore, it is designed to use imaginary part as the major method implemented in the detection. A reference curve with tolerance of 0.07Ω is constructed; and also a low cost and simple implementation method is proposed to qualify the crystals. To conclude, the work described in this dissertation provides a simple, viable and non-destructive methodology for the detection of cracks in piezoelectric ceramics. Experimental results revealed that imaginary part of impedance is a potential method applicable for the crack detection. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 991022122733103411.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 1.73 MB | Adobe PDF | View/Open |
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