Detection Sensitivity Analysis for a Guided Wave (GW) Structural Health Monitoring System

Abstract

The paper presents a detection sensitivity analysis for a guided wave (GW) approach to monitoring fatigue crack growth. Piezoelectric beamforming array (PZT) sensors were used to send and receive ultrasonic waves. In this “baselined†method, changes in sensor response are recorded between the installed and test conditions. Propagating cracks create line-of-site obstacles between arrays, thus more energy is reflected (pulseecho mode) and less is transmitted (pitch-catch mode) between sensor pairs. Any change in acoustic impedance, such as reduction in stiffness or thickness would also cause partial energy reflection, proportional to the relative impedance change. Two test configuration as presented here, including fatigue in 4-point bending and more traditional tension-tension. The purpose of the present study was to evaluate the sensitivity of this GW approach to damage size using the Length at Detection (LaD) statistical approach recently developed specifically to be applied to Structural Health Monitoring (SHM).