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mechanical engineering

TU composite research published in Advanced Functional Materials journal

In a recent article available on the Advanced Functional Materials website, researchers in the College of Engineering and Natural Sciences at The University of Tulsa have demonstrated a new composite that can indicate damage using visual, temperature or magnetic detection. The article “Multimodal Damage Detection in Self-Sensing Fiber Reinforced Composites,” written by TU Ph.D. candidate Matthew D. Crall, Samuel G. Laney (BS ’16, MS ’18) and Associate Professor of Mechanical Engineering Michael Keller, discusses how the new material is a significant step forward in developing biomimetic materials that allow for rapid and simple detection of damage. This new technology has potential applications in aerospace, where inspecting composite materials (such as carbon fiber or fiberglass) for hidden damage is a complicated and time-consuming process.

composite research
a) Schematic of the active microvascular material system used to deliver the liquid constitutive parts of the magnetic particles. b) Mixing of the liquids causing precipitation of magnetic material in the damaged region. c) Schematic of three modes of damage detection: visual, magnetic, and thermal. Each mode is possible because of the high contrast between damaged and undamaged areas provided by the magnetic particles.

Damage detection is critical in these applications since even small damaged regions in composites can reduce the strength of the material by as much as half. The composite works by incorporating a small channel, such as a blood vessel, that is filled with a liquid, like blood.  Damage breaks open the channels and the fluids bleed into the damaged area where they react and form magnetic particles. These particles can then be detected by a magnetic detector, heated by a magnetic field and imaged with an IR camera, or seen visually by the color change associated with the reaction.

To learn more about this research and the published paper in Advanced Functional Materials, please contact Associate Professor of Mechanical Engineering Michael Keller at 918-631-3198 or mwkeller@utulsa.edu.

Engineering team wins class prize

Throughout their collegiate careers, TU engineering students are encouraged to experiment with original ideas and tackle product design from scratch. For more than 20 years, Professor John Henshaw, chair of the Department of Mechanical Engineering, has tasked his students with performing failure analysis on commercial products. In 2014, the project became a class competition, and the winning team featured three female engineers.

Seniors Hannah Emnett, Hannah O’Hern and Katy Riojas, a 2015 Goldwater Scholar, under the team name KH2, conducted a failure analysis on a pair of German double-action bone-cutting forceps, used primarily in cardiovascular surgery. Of the eight independent analyses conducted by the team, Riojas said all pertained directly to the forceps’ material properties. “For example, in order to determine the specific type of steel used to create the forceps, we performed a microhardness test and a metallurgical analysis,” she said.

team project
Mechanical engineering students Hannah O’Hern, Katy Riojas and Hannah Emnett.

The students were required to answer three questions: How the forceps failed, how they functioned and how they could be redesigned to prevent additional failures. Team KH2 determined the forceps failed from mechanical overload caused by the stress concentration at the base of the device’s pincer. According to the team, the force required to cut a bone is much less than the force required to fracture the forceps, suggesting the forceps failed from misuse. Additionally, the surface clearly indicated a brittle fracture, which was further evidence of failure from misuse.

“Our mission was to take the design one step further and improve the safety of the forceps to prevent future failures, even those caused through misuse,” Emnett said.

KH2 recommended increasing the radius at the base of the pincer to minimize the stress concentration. Also, increasing the cross-sectional area at the base of the pincer would alleviate induced stress on the forceps. The redesign reduced maximum stress by 42 percent.

In addition to teaching students the importance of thorough product testing, Riojas said the process has confirmed her desire to pursue a career in medical device testing and design. She and the KH2 team received Lowe’s gift cards as the inaugural class winners of the Hackworth-Wilson Prize for Excellence in Failure Analysis, a new award named in honor of mechanical engineering alumni Matt Hackworth (BS ’96, MS ’98, PhD ’00) and Kelly (Wilson) Hackworth (BS ’96, MS ’98), former TU classmates who are married and now serve on the TU Mechanical Engineering Industrial Advisory Board. Matt’s project as a student in the mechanical engineering course involved the analysis of an exploded soda can under the mentorship of Henshaw.

“Matt and I did close to $1 million in external research for Alcoa, Coca-Cola, Anheuser-Busch and others,” Henshaw said. “When he and Kelly asked how they might give back to TU in a creative way, we established the Hackworth-Wilson Prize.”

To learn more about supporting students in the College of Engineering and Natural Sciences, please contact ENS Director of Development Natalie Adams at 918-631-3287, or natalie-adams@utulsa.edu.