Dianyun Zhang didn't plan on spending her career doing composites manufacturing.
She learned to love structures because of how critical it is for any aerospace engineering application, putting maximum effort into reducing weight to save cost and influence efficiency in aircraft and spacecraft.
But Zhang had been leaning more toward the structure performance side, not in the manufacturing itself. Until a project sponsored by GKN Aerospace while she was an assistant professor of mechanical engineering at the University of Connecticut altered her career trajectory.
Carbon-fiber reinforced composites have been around since the 1960s but only now are being used in larger applications, like in commercial aircraft.
"It's quite interesting," Zhang said. "We always get encouragement from industry coming to us for help and saying, 'This is some issue they would like us to solve on the fundamental side.' Even though they have lots of hands-on experience and know how to resolve it in a very practical way, they still would like to develop a fundamental understanding of the root cause of the issue so they can save time and money for their future manufacturing practice.
"This is a real-world problem that's not easy to solve. You're just going forever. Once you try to solve the problem, you find another good research area to pursue."
Zhang's research goal is to develop an integrated computational materials engineering approach by integrating physics-based and data-driven models to predict manufacturing-induced defects and the processing-microstructure-property-performance relationship of composite materials. Her focus is on multiphysics process modeling, multiscale modeling methods and progressive damage and failure analysis across different material length scales.
"It's a very exciting technology," Zhang said. "Over the years, we're trying to have a better understanding of the mechanics. Understanding the failure behavior. Now we're also trying to address the manufacturing issue because we think one of the reasons we still have to put pretty large safety factors for our design is we don't really have a good control of the manufacturing process. It ends with defects and the variability of the processes. We kind of over-design the structure.
"That's why I think in this area our research efforts trying to have a high-fidelity computational model can simulate both the manufacturing process and its performance and, eventually, we can really use the composite more efficiently to further reduce the structure weight."
There certainly are problems to solve. Despite the growing market demand for advance composites, grand challenges exist for the United States to be a leader in composites manufacturing. Reducing cycle time and process variability are the most crucial technical challenges, and workforce development is the most significant logistical barrier to grow the U.S. composites manufacturing industry.
Zhang, who joined the AAE faculty in fall 2020, is working to overcome those challenges by integrating a research and education plan to investigate the fundamentals associated with composite manufacturing processes and build a workforce pipeline.
Composite manufacturers currently are heavily reliant on in-house experience and trial-and-error approaches for process development, resulting in high manufacturing costs and long produce development cycles and limiting the innovations for new process and part decision. There are culture barriers between the manufacturers, material scientists and structural engineers, making the adoption of the process simulations a challenge. Zhang wants to create a composite ecosystem to intimately connect those groups, accelerating the use of lightweight materials in vehicle structures, leading to high fuel efficiency and low emissions.
"This is something we would like to try to do now, to simulate the manufacturing process, eventually link toward the structure performance so that the manufacture, the OEM, like an engine or aircraft manufacturer, they really can think about a design problem together," she said.
Zhang is finding the Composite Manufacturing & Simulation Center, a Purdue University Center of Excellence, at the Indiana Manufacturing Institute the perfect place to conduct research for her ongoing projects.
"Here we literally get everything I need for the experimental and simulation parts of my research," said Zhang, sitting in her office at IMI. "We can do manufacturing characterization and also through the software support. With the computational resources and the experimental resources, this is just a fantastic place where I can carry on my research."