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Professor Wards Off Fatigue — in Machines |
| By
Erica Ryan |
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Sep 30, 2002 |
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| Dr. Ali Fatemi, center, and doctoral students, Mehrdad Zoroufi, left, and Hui Zhang posed for a photo by the Instron Mechanical Testing Machine, which is used to characterize deformation, fatigue and fracture performance of materials. |
In the Fatigue and Fracture Laboratory in the North Engineering Building, the industry’s best mechanical components are put to the test. Dr. Ali Fatemi and his team of researchers twist, pull and bend specimens and parts with the help of state-of-the-art, computer-controlled testing equipment to determine if they will break or give out — before the product ends up hurting a potential consumer.
Many books and articles have suggested between 50 and 90 percent of all mechanical failures are fatigue failures caused by repeated loading. They can strike everyday items like doorknobs and bicycle pedals as well as complex structures such as vehicles and aircraft.
Fatigue failures can be very costly. “When a machine or structure fails, it can hurt or kill people, and it’s expensive to do a recall,” Fatemi said. “[Companies] try to avoid these problems through research.”
To help detect and prevent failures, the professor of mechanical, industrial and manufacturing engineering developed an experimental laboratory during his 17-year tenure at The University of Toledo to conduct most of his research projects.
Fatemi, who received one of the University’s Outstanding Research Awards last spring, has had 24 funded research projects with a total budget of $2 million. Some of his current projects include durability evaluation of connecting rods for the American Iron and Steel Institute, investigating joint fatigue failures for Ford Motor Co., fatigue performance evaluation of structural alloys for General Motors, and evaluating fatigue performance of forged versus competing process technologies for the Forging Industry Association.
Fatemi demonstrates fatigue failure by bending a paper clip — after repeated bending back and forth, the paper clip will snap. Through their research, graduate students in the Fatigue and Fracture Lab apply continuous repeated loading and pressure to more complex specimens and machinery to look for ways to predict and prevent a snap.
In addition to fatigue, Fatemi studies fracture mechanics, which deals with stress analysis of components or structures that have cracks or flaws. “There are always flaws in materials or from manufacturing. Cracks or crack-like defects exist all the time,” Fatemi said. “The airplane you fly in has many cracks. The job of the engineer is to make sure these cracks don’t grow or don’t grow too fast.”
Fatemi said the work in the lab focuses mainly on prevention of failures, and one of the aspects of his work he likes most is seeing his research applied. “I enjoy seeing that the solution works and they get around the failure or get around how the failure happens,” he said.
The lab, one of a few of its kind among engineering schools, is important to the research efforts. “We couldn’t do this kind of research without this facility,” Fatemi said.
The lab also allows students to get hands-on experience with fatigue and fracture studies. Fatemi has supervised the research of 28 graduate students, most of whom have used the facilities in this lab for their research.
Fengjie Yin, a third-year doctoral student, is one of eight current UT graduate students who works in the Fatigue and Fracture Lab. She is working on a project to predict fatigue life of casehardened materials used in gears and many other automotive components.
She said Fatemi has helped the students with their research and dissertations. “He’s a great adviser. He cares about us.”
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