Thermography Research Group Vibrothermography image of a cracked stator vane. Welcome to the web site of the thermography research group at Iowa State University's Center for Nondestructive Evaluation and Department of Aerospace Engineering. Our goal is to advance the state-of-the-art in nondestructive testing through basic scientific research. Our primary current efforts are focused around emerging needs in nondestructive evaluation. One major focus is on the basic science and engineering needed to support digital transformation in the nondestructive evaluation/nondestructive testing community (NDE 4.0). This includes methods for registering NDE data into physical geometric context, and fusing information from multiple sources into a coherent picture. It includes model-based inversion, the analysis of measurements based on computational sensing models. It includes the methods needed to acquire and make sense of such data in a coherent way. Another focus is on thermographic measurements of all types. Thermography uses heat and heat flows to find flaws. One major area of work has been vibrothermography, also known as "thermosonic", "sonic infrared", and "Sonic IR", which involves exciting a specimen with vibration and looking for heat generated at cracks. A piezoelectric stack generates the high amplitude vibration and the specimen is imaged with an infrared camera to see vibration-induced heating of cracks and flaws in the material. Current theory suggests that the heat is generated by frictional rubbing between crack faces. Our research group is working simultaneously to better understand the crack heating and vibration, and to develop improved measurement apparatus and experimental procedure. We are actively partnering with government agencies and some of the biggest corporate names in aerospace to assist in the development and deployment of vibrothermography. If you are interested in this technology, please contact Professor Stephen D. Holland for more information.