Mixing Minds and Methods in Materials Design

Collaborative research yields wide-reaching results

A blast rocks a seven-story building. The structure rumbles and sways with the explosion but stays intact. Inside the occupants are frightened but unharmed. Disaster has been averted thanks to something you can't even see...

That scenario will be made possible by super-strong nanoscale composites being designed and tested by a multidisciplinary team of researchers led by Mahmoud Taha, associate professor of civil engineering and Regents' Lecturer.

But the materials aren't the only new aspect of the research. New collaborations, a new development process, a new facility, and a new generation of engineers make this research even more promising.

New Diverse Collaborations

Taha has assembled a cross-disciplinary team from UNM and other universities to share their expertise for the research. He says that while managing large collaborative teams can be challenging, bringing together diverse scientific minds has great value. "Multidisciplinary teams produce very good returns and you can see ideas cultivated quickly," he comments.

The team includes experts on material optimization from the University of Illinois at Urbana-Champaign, researchers from the University of Texas San Antonio who focus on blast simulations, and material science experts from Georgia Tech. The core UNM team includes Marwan Al-Haik and Claudia Luhrs, both assistant professors of mechanical engineering, along with Taha and Jonathan Philips, National Lab professor in mechanical engineering. All the team members lend their expertise on nano-characterization and nanosynthesis of materials.

UNM's Center for Higher Performance Computing is central to the team's success. CHPC provides the parallel computation necessary for performing important simulations. Taha says that CHPC's advanced computational ability has helped the team realize achievements at the nano- and microscale that they never thought they'd reach.

The research team's main goal is to produce blast-resistant composites for use in the construction of buildings and bridges that can sustain explosions or serious impacts. "That's just the start," says Taha. "The material would be beneficial for many other applications. Aerospace and automotive manufacturing...there are thousands of applications for the material."

Besides being blast-tolerant, UNM's new materials will be strong, light, long-lasting, resistant to corrosion, and easy to work with. They will be fabricated into rods that can be set in concrete, replacing traditional steel rebar. Their unique structure will also allow engineers to monitor structural behavior.

A New Approach

The materials are innovative and so is the team's approach to creating them. "In civil engineering, it used to be that you would get a brick and be told to design a building with it," explains Taha. "Now we're handing the brick back and saying, 'This isn't good enough. We can make a better brick.' That's essentially what we're trying to do."

Nanotechnology lets the team turn the materials development process around and build materials from the ground up to meet certain specifications. The process is called "materials by design" and UNM's team is leading the way. "By re-defining our materials, we're establishing a new trend in civil engineering," explains Taha. "We will not use common trial and error methods to alter our materials as we used to do in civil engineering. Using nanotechnology, we will design our materials to perform the way we desire in a way similar to what we used to do in structural design."

First, the team simulates the material's abilities at the nano- and microscale. As the material starts to show promising characteristics, the team goes into the lab and builds it to their specifications. Then they test the material to see if it can withstand different types and levels of force and loading scenarios such as blast.

Specifically the team is focusing on "topological optimization," a process that helps determine the ideal microstructure of the composite material. The goal is to find the best way to organize carbon fibers and carbon nanotubes to make the material as blast-resistant as possible. To do that, the team is enhancing the microstructure of the fiber composites by using carbon nanotubes in a way that will increase the material's capacity by orders of magnitude.

"We have preliminary work showing that we've produced some very strong materials in blast-based computational models," says Taha. "We are investigating it further, looking for more microstructural optimization possibilities to produce these materials. And we're integrating the computational aspects with our years of experimental investigations." The team just started to publish their findings in scientific journals. They've also filed a patent on the new material through the university.

State-of-the-Art Facility

Taha, Al-Haik, and Luhrs have been awarded a total of $2 million in grants to pursue the modeling, development, and testing of the material. These funds are helping Taha and his team complete the new structural mechanics lab in the Centennial Engineering Center. "We are furnishing the new labs with state-of-the-art equipment for large-scale structural testing," says Taha. New equipment for the lab will include loading frames, actuators, large hydraulic pumps, a fracture mechanics testing machine, and computer-based data-acquisition instrumentation. The funds also helped UNM upgrade its nano-indentation facility, originally established by Marwan Al-Haik, to a top-of-the-line testing facility.

The array of new equipment opens up an entirely different level of testing and experimentation for the team. Now they can test full-scale walls, columns, and beams and compare concrete structures reinforced with conventional steel to those reinforced with the new composite material. The team will also be able to monitor the process of failure in the materials and record the failure at realistic loading rates. "Testing small specimens doesn't really represent how structures work. Scale in structures matters," explains Taha. "The behavior of structures at the macro-scale is very different than it is in micro-and nanoscale. We are establishing a multi-scale testing facility."

New Generations of Engineers

The new lab will help researchers introduce students to nanotechnology and give them a place for experimentation and observation. This is the first year that Taha has included nanotechnology in his introductory level undergraduate civil engineering materials class. "It's unusual to bring the latest technology and research to undergrads," he says. "But ten years from now, nanotechnology will be the core of materials design. That's why it's important to bring it into the classroom now."

Taha is also changing the way the materials lab is taught. Instead of having one teaching assistant run the lab, Taha has asked three doctoral students and one masters student to help. They get valuable experience and enhance their own education while helping undergraduates conduct experiments in the lab. "There's a lot of collaboration between the two groups and excellent knowledge exchange. The students are enjoying it too," says Taha.

Eslam Soliman agrees. As a civil engineering doctoral student and one of Taha's research assistants, Soliman will be working in the lab. The opportunity will help him advance his own research while giving him valuable collaborative experience with the mechanical and electrical engineering students involved in the project. "We work as a team and that gives us the opportunity to gain knowledge in different fields, which will be a great help for us in the future."

As for the future of the research, Luhrs says the potential is huge. "These kinds of studies enable scientists and engineers to design and manufacture lighter, stronger, less expensive, and cleaner products. Along with other groups devoted to the study of nano materials, we are participating in the design and generation of products that will fulfill the needs of our society."