Monday, May 6, 2019 - 3:30pm to 4:30pm
Extreme temperatures play a role in a growing number of engineering applications, including hypersonic flight, gas turbine engines, spacecraft re-entry, and next-generation nuclear reactors. In order to design for any of these applications, structural materials must be characterized to ensure that they can withstand the combined thermo-mechanical environment. One popular characterization method is digital image correlation (DIC), in which a deformable test specimen is patterned with a high-contrast surface pattern, then recorded with a high-resolution digital camera before and after deformation. An algorithm then compares the images to compute full-field displacements and strains. At extreme temperatures, materials emit light in the form of blackbody radiation which can saturate the camera sensors. This light is known to be brighter at longer wavelengths, and can be mitigated by using optical bandpass filters. In this work, it is shown that by using ultraviolet (UV) cameras, lenses, and filters the temperature range of DIC can be effectively extended. The UV-DIC technique is then applied to a variety of extreme temperature applications in order to measure heterogeneous strains at various temperature, time, and length scales.
Ryan Berke is an Assistant Professor of Mechanical and Aerospace Engineering at Utah State University, where he is the Director of the Mechanics at Extreme Temperatures Lab (www.berkelab.com) and USU’s Thermal Hydraulics and Material Properties Center (nuclear.usu.edu). He also serves as Chair of ASME’s technical committee on Experimental Mechanics and Secretary of the Society for Experimental Mechanics’ technical division on Fracture & Fatigue. He earned his B.S. in Mechanical Engineering from the University of Maryland and his PhD in Mechanical Engineering from The Ohio State University, where his dissertation research was on mechanical characterization of solid oxide fuel cells at high operating temperatures. He then worked as a postdoctoral researcher in Aerospace Engineering at the University of Illinois, where his research was on thermo-mechanical fatigue in nickel superalloys for sustained hypersonic flight. More recently, he was a summer faculty fellow at the Air Force Research Lab in their Turbine Engine Fatigue Facility. His lab uses advanced imaging techniques to study heterogeneous failure mechanisms at extreme temperatures, with applications geared towards the energy, aerospace, and nuclear industries.