Creating the next generation of structural materials

Mostafa Hassani knows the technologies of the future cannot rely on the structural materials of the past. Melting metals and then mixing and shaping them into useful configurations was fine for thousands of years, but engineers and designers are asking more of structural materials than the old processes and materials can deliver.

Hassani sees himself as a bridge between mechanical engineers and materials scientists, since he has a foot firmly planted in each of those worlds. Hassani, who joined the faculty of Cornell’s Sibley School of Mechanical and Aerospace Engineering in 2019 as a senior research scientist and is now an assistant professor, believes that this academic bilingualism makes Cornell Engineering the perfect place for him.

“The Sibley School has got such a great reputation for mechanical engineering. And when you combine that with the groundbreaking materials research that happens at the Department of Materials Science and Engineering and the fabulous facilities like CHESS and CNF, why would I go anywhere else?” Hassani said. (CNF is the Cornell NanoScale Science and Technology Facility.)

Hassani’s Extreme Mechanics, Materials, and Manufacturing (EM3) Lab has several interwoven areas of focus. One is structural materials processing and design where Hassani exploits the great promise of advanced and additive manufacturing (AM) techniques to create stronger, lighter, and more sustainable structural materials.  Hassani wants to advance researchers’ understanding of the relationships between the processing, the microstructure, and the resulting properties of structural materials. One special area of attention is structural materials that do not rely on molten metals as part of their creation process.

A second area of focus is elucidating the processes of deformation and mechanical failure of structural materials. No material lasts forever so it is essential that researchers understand what happens to crystalline and amorphous metals and alloys, ceramics, and composites as they deform, fracture, and fatigue. This is where some of the specialized facilities at Cornell are essential. Electron microscopes can show what is happening at the surface of materials, but they can’t show what is happening inside. The Cornell High Energy Synchrotron Source (CHESS) gives researchers a way to see inside. Hassani uses high intensity x-ray beams available at CHESS to unravel the underlying deformation and failure mechanisms experimentally.

A third area of focus is on micro-projectile impact testing of structural materials. “Our small-scale impact experiments open ways to high-throughput characterizations of materials performance and energy absorption mechanisms under extreme conditions. This in turn can significantly accelerate material discovery and design for dynamic loading applications.” Hassani said. He added that Cornell is uniquely positioned for research into micro-projectiles. “Measurements and characterizations of materials that are currently conducted post-mortem, i.e., after impact, can be done in-situ, i.e., during impact deformation using high-intensity X-rays. This enables a significant advance toward a more comprehensive understanding of materials under extreme loading conditions.”

Hassani earned his bachelor’s degree in mechanical engineering at Iran’s University of Tabriz. He then moved to Tehran for his master’s studies in mechanical engineering at the Sharif University of Technology. At that point he knew exactly what he wanted to focus on during his doctoral studies and joined the group of Professor Mario Guagliano at the Politecnico di Milano in Italy to earn his PhD degree with a focus on improving fatigue performance of structural materials. To give a materials science perspective to his research endeavors, Hassani completed a postdoctoral appointment in the Department of Materials Science and Engineering at MIT, working with Prof. Christopher Schuh, before coming to Cornell.

Hassani says he never seriously considered going into industry at any point in his academic progression. “I have always loved teaching. In that way I am like my mother who is the most dedicated teacher I have ever seen. She and I both get so much enjoyment and fulfillment from answering questions and helping other people understand things,” Hassani said.

When Hassani is able to take his mind off of structural materials and questions of how to make them better, he enjoys playing soccer, cooking, and listening to podcasts that tell real people’s stories.