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Undergraduate and Graduate Students Help Design Blast-Resistant Materials

Though the United States has never experienced a terrorist attack on trains, protecting rail cars from explosions has never been more important: the Pentagon said evidence seized from Osama bin Laden's compound showed al Qaeda hoped to launch an attack on U.S. trains.

So how could we be prepared for such an attack? That’s where faculty and student engineers come in. At the McCormick School of Engineering and Applied Science, students at all levels are working on a project funded by the U.S. Office of Naval Research that aims to make civilian trains more resistant to bombs.

The multidisciplinary project began seven years ago, after the train bombings in Madrid that killed 191 people. With the backing from a grant from the Navy, professors and students began using state-of-the-art computer modeling and specially designed blast chambers to design new structures and steels that could protect civilians from a terrorist blast.

McCormick is suited for such a task: Greg Olson, Walter P. Murphy Professor of Materials Science and Engineering, is considered one of the founders of computational materials design. He directs the Materials Technology Laboratory/Steel Research Group and founded QuesTek Innovations LLC, a materials design company that was selected for Fortune magazine's list of the 25 breakthrough companies of 2005.

Olson developed physics-based, computational tools that allow researchers to design and simulate new types of materials based on desired properties. So each year, Olson assigns students at all levels to build on previous students’ work to ultimately create the best possible protection for train cars.

“This project shows how we can use long-term graduate funding to help undergraduates do very high technical work,” he said. “Multiple design classes have now participated, and each year students give a fresh eye to the research.”

Currently, a group of students in the first-year Engineering Design and Communication course are working with Trinity Rail to develop new blast resistance strategies for rail cars carrying chlorine. Chlorine cars are a potential target because the gas is colorless, odorless, and can kill bystanders quickly.

The group is studying both steel alloys and blast-resistant structures to develop new shields for the cars.

“We tried to combine new steels that are better for blast resistance with advanced structures to see how much of a blast we’d be able to protect against if we put the shield on a train car,” said freshman Bridget Gibbons.

To do this, these freshman-year students have performed calculations to determine how much certain type of structure or steel would react after a blast. They’ve found that a shield with an I-core structure (two pieces of metal connected with another vertical piece) works best because it absorbs energy before it deflects it – ideal for a rail car with little space to deflect.

The group is now studying how to best fit a blast shield onto a rail car that has already been optimized for mass and shape.

“This project combines both experimental and theoretical data,” said freshman Sid Narayanan. “We’re not expected to build the shield, so we can see how far our imagination’s stretch on paper before proving our conclusions.”

Another group of students in the higher level MSE390 Materials Design course is considering how to create a more blast-resistant steel alloy. Using Olson’s computational design software and his framework for developing materials using thermodynamics, the team is researching how to create a steel alloy that has maximum uniform ductility, or stretchiness at the point of impact.

That stretchiness is important when using blast-resistant panels; it allows those panels to better absorb energy. To get the best ductility, students have been using finite element modeling, which calculates not only the best mix of materials but also how those materials should be processed.

“If we alter processing times, or put it in the furnace for different amounts of time and temperatures, what tradeoffs do we get?” said Zack Feinberg, the group’s graduate student leader. “How do we change the processing to get the structure we desire with the right properties and performance? That’s ultimately what we’re looking into.”

For students, the project gives them a realistic look at the materials industry with a project that has the potential to save lives.

“We usually only see lots of equations, principles and models on paper,” said senior Anthony Tan. “Through this project I’ve found that how to use those principles and put them into models to help design something better.”

Alvin Tan, a veteran of the Singapore army, said he has seen first hand how materials are used in defense systems.

“I’ve thrown hand grenades, set up explosives, and fired automatic weapons,” he said. “I feel that in defense applications, materials make all the difference. Something like this really has the potential to save lives.”

The group hopes to enter their work in the ASM Materials Education Foundation’s Undergraduate Design Competition, where Northwestern has won or placed with this project for the last several years.

“The students have been extremely successful with this project,” Olson said. “They’ve learned how to apply their materials science training to an important issue, and they get a chance to be mentored by both faculty and graduate students. It’s a win for everybody.”