ORCID Profile
0000-0002-4329-0285
Current Organisation
Institute of Materials Research and Engineering
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Publisher: Trans Tech Publications, Ltd.
Date: 10-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.1043.263
Abstract: Over the past few decades there has been significant advancement in the development of microelectronics. This has attracted attention of micro-scale energy harvester systems that could harvest energy from the operating environment of the microsystem. In this paper, rain energy harvesting using piezoelectric beam is tested. This paper seeks to create an experimentally validated proof of concept piezoelectric rain energy harvester using a piezoelectric beam. A rain simulator consists of six solenoid valves is designed to simulate different rain types. The effect of multiple water droplets impinging different positions on the piezoelectric beam is studied in this paper. Results show that a 4.5 ± 0.2 mm diameter water droplet falling at height of 0.82 m impinging the piezoelectric energy harvester is capable of generating a peak power of 0.16 mW.
Publisher: SAGE Publications
Date: 07-02-2022
DOI: 10.1177/14759217211073950
Abstract: Fatigue cracks initiated from fastener holes are common in aircraft structures. Implementation of effective structural health monitoring (SHM) system to detect or monitor fatigue cracks near fastener holes is desired for realizing condition-based maintenance with improved aircraft safety at reduced cost. In this work, direct-write piezoelectric ultrasonic transducers were used for monitoring crack near fastener hole. Made of poly (vinylidenefluoride-co-trifluoroethylene) [P(VDF-TrFE)] film and annular array electrodes, the direct-write piezoelectric ultrasonic transducers were both directly coated and patterned around the fastener holes. A novel ring-design using annular array electrodes with small footprint was proposed to detect fatigue crack initiated in the vicinity of a fastener hole using pulse-echo and pitch-catch methods. The ring-design direct-write piezoelectric ultrasonic transducers were designed to operate with Lamb wave modes at 1.5 MHz. A numerical simulation study was conducted to investigate the interaction of Lamb wave modes with the fatigue crack. Experimental ultrasonic testing was performed with signal gates determined using wavelet analysis. Fatigue crack detection was demonstrated using an energy ratio method by comparing energy parameter of gated ultrasonic signal with baseline signal. Using the pulse-echo method, the direction of the fatigue crack was able to be determined. The pitch-catch method was found to have higher sensitivity in fatigue crack detection but could not determine the direction of the fatigue crack. These transducers made of thin films promise high conformability even on curved surface and around irregular objects with limited space, compared to conventional discrete ultrasonic transducers. The analysis and results showed that the ring-design direct-write piezoelectric ultrasonic transducers have great potential for fastener hole SHM.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 08-2201
Publisher: SAGE Publications
Date: 29-08-2021
DOI: 10.1177/14759217211040719
Abstract: In this work, direct-write piezoelectric transducers (DWTs) were made by spraying piezoelectric poly(vinylidene fluoride-co-trifluoroethylene) coating with comb-shaped electrodes on carbon fibre reinforced polymer (CFRP) plates for drop weight impact damage detection. Their ability and performance were investigated and compared to discrete piezoelectric lead zirconate titanate (PZT) ceramic transducers that were adhesively bonded on the same CFRP plate. Guided wave signals were acquired with different combinations of actuator-sensor involving DWT, PZT and laser ultrasonic excitation, in pitch-catch configuration. DWTs allowed consistency and simplified signal interpretation due to an effective mode selection (A 0 or S 0 mode) with wavelengths of 10 and 12 mm. PZTs generated stronger but much more complex signals and mode selection with a larger wavelength (20 mm). The configuration with PZT as actuator and DWT as receiver showed the highest signal litude changes of A 0 or S 0 mode, allowing efficient detection of damage introduced by a 31 J impact. Further ultrasonic B- and C-scans revealed a 27 mm long crack on the plate’s backside developed in addition to internal cracks and delaminations of about 34 mm in length. For realizing contactless ultrasound excitation, a neodymium-doped yttrium aluminium garnet laser (wavelength of 1064 nm, 5.4 ns pulses) was used to replace the surface-mounted brittle PZT. The combination of the broadband laser excitation with the DWTs as sensors achieved more reliable damage detection than equivalent PZTs, attributed to DWT’s effective single mode selection. In addition to reduced weight, the polymeric coated DWTs allow large area implementation (scaling up), even on curved surfaces due to their flexibility and conformability, in contrast to adhesively bonded discrete transducers.
Location: Malaysia
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