Crack Detection Methods Using Radio Frequency Identification and Electrically Conductive Materials

Radio Frequency IDentification (RFID) tag is a promising device for the management of products at a very low cost. Huge number of such low-cost sensors can be installed to the structure beforehand, after a disaster we can access to these sensors wirelessly and very easily. In this system, a printed sheet is applied to a part of structure in which crack will occur. Copper wire is connected to the attachment on the structure and a RFID tag. When a crack occurs, the printed sheet is broken, resulting in an increase in resistance. Crack width can be estimated by the ability of an RFID transmitter to communicate with the tag. By fatigue test of steel specimen with a notch, the relationships between crack width and conductivity of the materials are examined. It is shown that the level of crack width can be related to the ability of the printed sheet to conduct electricity or not. Very small steel crack can be detected by this sensor.