UC San Diego

Sudden crack growth has the potential to cause catastrophic failure when a crack reaches a critical crack size. Early detection of crack formation minimizes this potential. This research focuses on the use of guided ultrasonic waves (GUWs) to detect crack formation. Experiments conducted on aluminum test specimens grew fatigue cracks through cyclic loading. Macro Fiber Composite (MFC) and piezoelectric disc transducers induced and received various GUWs ranging in frequency from 25 to 100 kHz. Features were extracted and correlated to crack length in the time domain, frequency domain and from autoregressive models of time series sensor data.