Various engineering structures develop defects and flaws over time due to environmental effects, overloading, wear and tear, fatigue, corrosion and other unavoidable degradations. These flaws pose risk of failure to the whole system, especially when a component is approaching its designed life. In particular, aerospace systems rely heavily on the structural components, and their damage often leads to catastrophic failures.
Conventionally, Eddy current Testing (ET) and Ultrasonic Testing (UT) is carried out in aerospace sectors, which require detaching the components in most cases. Research is being carried out in aerospace sectors to examine large areas using few transducers. Guided Wave Ultrasonic Testing (GWUT) has recently evolved as a feasible in-situ testing technique for most structures. However, for continuous GWUT based Structural Health Monitoring (SHM), Wireless Sensor Networks (WSN) need to be deployed. But higher excitation and operating frequencies, high sampling rates, large data volumes, and complex processing increase the cost and power consumption; rendering various WSN platforms infeasible.
To meet such stringent constraints, the solutions previously reported tend to use more power hungry platforms. This work proposes a complete remote sensing solution featuring a novel signal conditioning circuit design, which enables low-power, low-cost sensing for wireless GWUT based SHM systems. The circuit is designed to sense, pre-amplify and extract the envelope of the GWUT signal. The extracted signal is then transmitted wirelessly using a low-power zigbee mote over custom designed application protocol. At the Base station, the signal is reconstructed and processed to detect and localize flaws, by comparing against a reference signal. Thus, a detailed remote sensing system design is presented for a wireless GWUT based SHM system.