Creating waves in solids: MAE collaboration on materials research
Mechanical and Aerospace Engineering Professor, Marat Khafizov, and MAE graduate student Yuzhou Wang took part in a collaborative project with researchers from Idaho National Laboratory (INL). The multi-institutional team worked to demonstrate how sound waves generated by light can be used to observe materials’ inner structure. This discovery enables future research to monitor a material’s inner structure while it is being subjected to extreme conditions.
The research demonstrated a new method to measure crystallite orientation in a transparent ceramic material. Khafizov said the basic idea behind this approach is “similar to dropping a rock on the surface of water and watching wave ripples propagate on the surface.”
While waves on the surface of the water are visible to the eye, the acoustic waves resonating inside the solid material are a result of atomic vibrations. These require a different approach to detect.
“Instead of a rock, we use a very short laser pulse focused through a microscope objective to launch the wave inside a solid material,” said Khafizov. “To observe the ripples, we use a different laser pulse.”
The second laser pulse is used to detect any changes in optical transparency of the material that can occur as the wave ripples through the solid. The unique aspect of measuring these waves in solids is that unlike liquids, which only produce longitudinal waves, solids can produce three different types of waves. These wave types are determined by the different directions atoms vibrate as the wave propagates.
Much of the hands-on work was performed by nuclear engineering graduate student, Yuzhou Wang. Other portions of the measurements were done by Wang at experimental facilities in Idaho National Laboratory during his summer internship. Wang took these measurements and brought them back to Columbus for interpretation as part of his PhD dissertation.
Other contributors to this project were INL research scientist, Dr. David Hurley, and professors at Le Mans University in France, who helped establish a foundational basis for the experimental and theoretical components of this project. The team at Ohio State led interpretation of the experimental observations that allow measurement of grain orientation.
Khafizov said the chance to perform research with INL is a valuable experience for Ohio State students. Alongside scientific leaders in laser ultrasonics, graduate students worked to recognize and identify new information from the experiments. The opportunity to spend time at INL and work with their researchers is made possible in part by Ohio State’s participation in the INL National University Consortium.
The results of this research are already being implemented in new projects. One use is inspecting material grains as temperature changes, to understand limits of material thermal conductivity.
According to Khafizov the results of the research benefit multiple areas. It could allow development of ceramic materials that advance clean and secure energy systems. The project could also be applied to defense by providing optical ceramics for high powered lasers, and ceramic armor.
However it is applied, the research done by MAE faculty and grad students in collaboration with INL will help advance the areas of materials research and laser ultrasonics.
Written by Sam Cejda, Department of Mechanical and Aerospace Engineering
