Uncertainty quantification of a guided wave structural health monitoring system for composite bolted joints

Assessing the robustness of a sensor system and the related predictions is a key step in structural health monitoring (SHM). In this paper, the SHM system under consideration uses macro fiber composite (MFC) sensors to generate ultrasonic guided waves for inspection of a composite bolted joint. Bolt bearing failure is introduced to a target hole through tensile loading. The MFC sensor-actuators are configured in a circular array around the target hole and used to send and receive the ultrasonic waves from many different directions. This strategy facilitates a scattering matrix approach to identifying the most effective actuation and sensing angles for damage detection. Multiple interrogation wavelengths are also utilized to study the effect of the wavelength relative to the size of hole being monitored. However, various other factors are expected to impact the ultrasonic signal and therefore the damage detection results. Particularly, the position and orientation of each sensor is precisely measured through image processing techniques in order to quantify the effects of sensor misalignment. Finally, the sensitivity of the ultrasonic inspection technique to variation in each phenomenon is compared to better understand the most significant effects on damage detection performance.