Prof. Andrew Makeev and Research Engineer Brian Shonkwiler at the University of Texas Arlington Mechanical and Aerospace Engineering department operate a dynamic DIC testing laboratory. Together they conduct a variety of DIC tests ranging from quasi-static to extremely dynamic testing. In this particular example, UTA are utilizing the VIC-3D UHS-HPVX2 system to measure dynamic properties of a glass/epoxy material. The purpose of this Short Beam Shear test is to measure multiple material properties such as shear & axial modulus, and shear strength.
The turnkey system from Correlated Solutions includes two Shimadzu HPV-X2 cameras which are conveniently controlled with Correlated Solutions’ software VIC-Snap UHS. The images are acquired during the event, downloaded, and then post-processed with VIC-3D. The frame rate for this test was 666,667 FPS with a 200 nano exposure. The specimen was speckled using a permanent marker, and an extremely bright stroboscope was used to illuminate the specimen. The impact velocity was 10 m/s, and the specimen reached approximately 3.5% shear strain at failure, which took approximately 100 microseconds.
As Mr. Shonkwiler states, “The purpose of the impact test is to determine how the dynamic characteristics of the material properties differ from the static properties. The importance of using the VIC-3D system is the fact that there are steep strain gradients on the face of the specimen. We would never get the strain information we need using a strain gage.
DIC is enabling a more efficient means of finding material properties of materials. The standard test methods require many different types of tests that often use relatively large specimens. The short beam shear specimen is small, which allows one to make hundreds of specimens from a small panel. Additionally, since composites are not isotropic, the material properties can vary from the 1-2, 1-3, and 2-3 planes. We can get properties from all three planes by simply cutting the short beam specimen from the panel at a different orientation or by flipping it, and so DIC has been an essential tool for our research as it helps us understand the behavior of these complex materials in great detail due to the full-field nature of the technology. This technology will be useful for any industry which needs composite materials properties.”
Below is an animation created in VIC-3D from the test data showing the first principle strain (e1) vs. time (ms) at the two extracted points P0 and P1.
* Data Courtesy of Prof. Andrew Makeev from University of Texas Arlington
Airbus has built a reputation for innovative aircraft, recognized around the world for their safety and efficiency. All of these attributes are driven by a top-notch testing program, whose innovative practice are evidenced by their use of the VIC-3D measurement system.
One of the goals of the Airbus testing program is to characterize the structural damage caused by collisions between the aircraft and small projectiles such as birds and other ground based debris, and to ensure that the structural integrity of the aircraft is maintained.
This type of event can be reproduced by firing a variety of different types of projectile at a piece of aircraft structure at a high velocity. The results obtained can be used to compare with computer models of the structure under impact loads, leading to more highly optimized and safer designs.
Dr. Richard Burguete, experimental mechanics specialist at Airbus UK since 1997, explains the benefits of this approach as follows: “The VIC-3D system allows us to be sure we have captured all of the relevant data, some of which might have otherwise been unobtainable.”
View the VIC-3D system for more information about this technology.