Data Acquisition through Non-Destructive Evaluation
IGERT-TEECH Trainees are exposed to a broad range of 'local' and 'global' sensing technologies to monitor the health of cultural assets such as historic buildings and statues. The non-destructive evaluation (NDE) and structural health monitoring (SHM) communities are traditionally divided into local approaches, providing detailed information on components (e.g., defects at a specific location), and global approaches, providing information on general behavior at the system level (e.g., a decline in modal frequencies). Examples of local NDE/SHM techniques are ultrasonic testing, eddy currents, and X-ray radiography. An example of global NDE/SHM techniques is modal testing. Because the "local" and "global" approaches are complementary in nature, IGERT-TEECH is exploiting both classes of techniques to provide the most comprehensive information on the state of health of an artifact while limiting the number of sensing points. This local-global approach will be performed in two stages:
Many NDE/SHM techniques necessitate an excitation to the structure in order to highlight damage, but studies indicate that the use of passive excitation shows promise. IGERT-TEECH will further the use of passive excitation in order to simplify the sensing apparatus. One example novel approach will be developed by coupling optimized, tailored ultrasonic waveforms (input shaping) with pattern recognition techniques rooted in generalized notions of correlation, information theory and sensor inter-dependence that can result in probabilities of detection for targeted defects approaching 99%.
A combination of multi-spectral imaging techniques,(infrared, ultraviolet, visible and others) and other techniques, including acoustic, radar, X-ray, gamma-ray and terahertz, will provide a powerful palette of interrogation tools for temporal surface, sub-surface and volume characteristics of an artifact. Most of these techniques can be used to assess the state of health of all kinds of cultural assets, but they will be applied specifically in IGERT-TEECH to paintings, historic structures, and archaeological artifacts and