In aerospace applications, such as during hot-fire rocket testing, materials must withstand high-speed loads in high temperature environments. In these environments, typical contacting methods of measurement such as strain gages are not reliable because they are damaged under the harsh testing conditions. To collect data, non-contacting methods such as Digital Image Correlation (DIC) become preferable.  However, at extreme temperatures, the paint used for the DIC speckle pattern can burn or peel from the specimen unless specialized high temperature paints are used. In addition, heated objects emit light in the form of blackbody radiation which can saturate the camera sensors. The emitted light is known to be brighter at longer wavelengths, so by pairing DIC with an ultraviolet (UV) camera and optical bandpass filter which has a relatively low wavelength compared to visible light, the temperature range of DIC can be effectively extended. This technique, known as UV-DIC, has been demonstrated up to at least 1600°C in lower speed experiments using UV capable cameras. However, to perform UV-DIC at high speeds in addition to high temperatures, a high speed camera that can detect UV light is needed, but most commercial high speed cameras perceive low amounts of UV light. To increase the amount of UV light that the high speed camera receives, a UV amplifier designed for high speed applications is used. To demonstrate the UV amplifier’s ability to collect high temperature and high speed data, three tests are performed. First, to demonstrate the high temperature capability of the UV amplifier, a quasi-static test is performed where a graphite specimen is heated to 1600°C to measure the thermal expansion. Second, to demonstrate the high speed capability, a cantilevered plate is vibrated to resonance at approximately 220 Hz, and the mode shape is recorded at high speed. Finally, the combined high temperature and high speed capabilities are demonstrated by heating the vibrating plate with an induction heater. Each test is performed in three different configurations. In the first configuration, the DIC images are collected with the high speed camera and no UV equipment. This gives a baseline of the data, and demonstrates the shortcomings of unfiltered DIC in high temperature experiments. The second configuration, images are taken with UV lights and a UV optical bandpass filter, but no UV amplifier. This demonstrates the low UV sensitivity of the high speed camera. In the final configuration, images are taken using the UV amplifier, UV lights, and UV bandpass filter, thus demonstrating the combined ability to detect full-field deformation at high speeds and extreme temperatures.


Demonstration of UV-DIC at High Speed and Extreme Temperatures

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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