Digital Image Correlation Techniques for NDE and SHM

Monitoring and analyzing the integrity of structures, infrastructure, and machines is essential for economic, operational, and safety reasons. The assessment of structural integrity and dynamic conditions of those systems is important to ensure safe operation and achieve or even extend the design service life. Recent advancements in camera technology, optical sensors, and image processing algorithms have made optically based and noncontact measurement techniques such as photogrammetry and digital image correlation (DIC) appealing methods for nondestructive evaluation (NDE) and structural health monitoring (SHM). Conventional sensors (e.g., accelerometers, strain gages, string potentiometers, LVDTs) provide results only at a discrete number of points. Moreover, these sensors need wiring, can be time-consuming to install, may require additional instrumentations (e.g., power amplifiers, data acquisition), and are difficult to implement on large-sized structures without interfering with their functionality or may require instrumentation having a large number of data channels. On the contrary, optical techniques can provide accurate quantitative information about full-field displacement, strain, geometry, and the dynamics of a structure without contact or interfering with the structure’s functionality. This chapter presents a summary review of the efforts made in both academia and industry to leverage the use of DIC systems for NDE and SHM applications in the fields of civil, aerospace, and energy engineering systems. The chapter also summarizes the feasibility of the approaches and presents possible future directions of the measurement approach.