Measurement of Temperature, Dynamic Strain Amplitude and Spectra Using a Single SAWR

Dynamic strain sensing is an important diagnostic tool in monitoring the health of structures, identifying when maintenance is necessary, maintaining equipment operation, and ensuring workplace safety. It is particularly important in power generation, automotive, and aerospace applications, and in high-temperature (HT) harsh-environment (HE) applications. Some of the challenges present in dynamic strain sensing are adhesion, packaging, stable long-term operation, and cross-sensitivity temperature compensation. Surface acoustic wave resonator (SAWR) sensors have been shown to meet these demands and offer additional features such as compact size and wireless interrogation. In this work a single SAWR is used to simultaneously measure temperature, dynamic strain amplitude and spectra. Since the SAWR sensitivity to dynamic strain is temperature dependent, the intrinsic capability of the device to measure its own operating temperature allows the selection of the correct dynamic strain calibration slope. The SAWR resonant frequency is continuously tracked in real-time, allowing for the measurement of temperature. The measured temperature is then used to select the correct dynamic strain calibration slope. Finally, the dynamic strain is obtained from the relative amplitude of the spectral components to the main peak. With one single SAWR, temperature, dynamic strain, and spectral components of dynamic strain are all measured.