Researchers at the University of Central Florida (UCF) (Orlando, Florida, USA) are working on a new project to further develop computer models related to stress-corrosion cracking (SCC), with a goal of better pinpointing the initial stages of the problem.
For this purpose, the U.S. Defense Advanced Research Projects Agency (DARPA) (Arlington, Virginia, USA) recently awarded a $100,000 grant to UCF's aerospace engineering department to further refine and enhance these models.
“One small crack in an aircraft component can lead to major problems,” UCF writes in a news release.1 “The cracks can grow fast and damage metal components to the point of failure, but they are often hard to detect.”
Learning Where SCC Begins
Ranajay Ghosh and Seetha Raghavan, both of whom are aerospace engineering professors at UCF, will lead the project. According to UCF researchers, SCC in aircraft components typically occurs when stress and corrosion create cracks in metal pieces, such as engines, wings, and landing gears. These are also the areas that can quickly lead to catastrophic failure.
“These cracks often initiate at sub-micron or even nanometer length scales and thus can stay undetected for quite some time,” Ghosh says. “By the time the cracks are visible, damage is already well underway.”
SCC is often observed in lightweight aerospace materials, particularly aluminum. Although it’s a serious and potentially life-threatening issue, researchers don’t know exactly how it starts. That’s a mystery Ghosh wants to try and solve with state-of-the-art computer models.
Progress of Modeling
Once the computer models are developed, they could lead to the creation of physical models, and ultimately, early SCC detection and warning systems that could isolate damaged areas. They could also lead to the design of materials and coatings that are resistant to SCC damage.
To create the models, he plans to use powerful computers to solve and analyze complex scientific equations. “These equations will be analyzed in great detail and compared with sophisticated x-ray techniques to improve accuracy,” Ghosh says. “The resulting model will then be used to create a computer simulation of crack initiations under some of the common conditions that are already known to cause stress corrosion cracking.”
Because the rates of corrosion and oxidation occur rapidly at the microscopic level, Ghosh says he will use data from synchrotron x-rays, described as extremely powerful light beams created in a particle accelerator. The x-ray data will be captured at Argonne National Laboratory in Lemont, Illinois, USA, using advanced instrumentation and measurement techniques developed by Raghavan during the past decade.
The x-rays will allow them to observe the micro-structural degradation and oxidation of SCC in real time, and that information will be fed into the computer models. “We’re using a state-of the art, in situ sample environment design to attack an age-old problem,” Raghavan explains.
This project is funded under DARPA’s Polyplexus pilot program, a derivative of the organization’s new collaborative platform called Polyplexus. This public social network, which launched in 2019, allows members of the research community to connect with DARPA’s program managers to explore potential research opportunities.
Additional information on this research is expected in the months ahead.
Source: UCF, www.ucf.edu.
1 “UCF Professor Receives Grant to Determine How Cracks in Aircraft Components Start,” UCF News, Oct. 9, 2020, https://www.ucf.edu/news/ucf-professor-receives-grant-to-determine-how-cracks-in-aircraft-components-start/ (Nov. 16, 2020).