Detection of Surface Cracks in Metallic Materials Using an Enhanced Symmetrical Split Ring Resonator

An enhanced sensor based on symmetrical split ring resonator (SSRR) functioning at microwave frequencies has been proposed for detecting and characterizing the cracked surface of the metal materials. The enhanced SSRR sensor is modelled using a High Frequency Structure Simulator (HFSS) and the reflection S11 is performed for testing the aluminum metal with crack and without crack at the frequency range of 100 MHz to 3GHz. Variation of crack width and depth has been investigated and the most obvious finding emerged from this study is that the ability of detecting a minimum of sub-millimetre crack width and depth which is a round 10 μm width or depth where the minimum shift of reflected frequency is recorded at 6.2 MHz and 3 MHz for crack width and depth respectively. The enhanced SSRR provides high capability of detecting small crack defection by utilizing the interaction between coupled gap resonators and it is useful for various applications such as aircraft fuselages, nuclear power plant steam generator tubing, and steel bridges and for others that can be compromised by metal fatigue.