Thermomechanical Response Measurement on Composites Using Infrared Thermography and DIC
Specimen: Sandwiched E-glass composite with balsa core
Heater: Steel plate heated by induction heating
Loading: Thermal up to 120°C and compressive load at 4670 N
DIC: VIC-3D with 11 MP cameras + FLIR SC655 (640 x 480 resolution) camera
Understanding the thermo-mechanical behavior of materials can be a vital component when designing vehicles and structures that may be exposed to high temperatures. Virginia Tech’s Extreme Environments, Robotics, and Materials (ExtReMe) Laboratory focuses on the impact of extreme environments on materials. This includes research that is focused on understanding the thermo-mechanical behavior of materials both during and following fires. Experimental investigations are performed to understand the evolution of the material due to elevated temperature.
The senior research associates in the lab used the VIC-3D IR system to find the effects of a simultaneous one-sided heating and compressive loading test on an e-glass/vinyl ester/balsa wood sandwich composite sample. As one researcher stated, “The VIC-3D IR system identified several transient events during the compression tests which would not have otherwise been fully understood using either DIC or IRT independently. Through this testing, several features of sandwich composite thermomechanical behavior were elucidated which would not have been possible with traditional point measurements (i.e., strain gauges, deflectometers, or thermocouples).”
The data in the images and graphs below display the strain and temperature data extracted from the two locations C1 and C2. The strains peak at the highest temperature and then become smaller as the surface cools when the sample’s surface delaminates and blisters.
Calibration Target:
Black anodized aluminum plate with laser etched circular markets. This provides high emissivity contrast in IR cameras and white light cameras.
Speckle Pattern:
High temperature matte black spray paint was applied as a base coat with 18 μm thickness. It was determined that the thin white speckles had a negligible effect on the IR measurement compared to black paint only.
Data extracted from C1 and C4 locations shown above
Data shows as strains decrease due to blistering, cooling occurs
Data courtesy of Nathan Cholewa and Patrick Summers and Virginia Polytechnic Institute and State University.