Surface Crack Characterization of Aluminium Specimen using Passive Wireless RFID based Tag Antenna Sensor

This paper presents an Ultra High Frequency (UHF) Radio Frequency Identification (RFID) based tag antenna sensor for surface crack characterization of an aluminium alloy 6061 T6 grade specimen. Tag antenna was optimised using HFSS®, Ansys Inc., USA software. The designed tag is simulated on the specimen with various crack dimensions and oreintations. When the crack depth is varied from 0 to 1 mm, the observed average absolute change in resonant frequency $(\vert \Delta \mathrm{f}_{\mathrm{r}}\vert )$ for vertical, horizontal, and diagonal orientation cracks is 2.19 MHz, 0.39 MHz, and 1.05 MHz, respectively. Similarly, for varying crack depths from 1mm to 6mm, the observed frequencies are 10.21 MHz, 0.6 MHz, and 4.5 MHz, respectively. Simulation results show that the proposed sensor is sensitive to submillimeter cracks, enabling the detection of surface cracks at an early stage.