Metamaterials to Reduce Drag and Enhance Maneuverability in Aircraft

Mechanical metamaterials are engineered structures that have unique properties that are not possible with natural materials. Now, they are being applied to aircraft to reduce drag and enhance maneuverability, feats that would decrease energy requirements in the field of air vehicle operation.

Researchers from the University of Pennsylvania, the University of Illinois Urbana-Champaign, California Institute of Technology (Caltech) and Boston University have been awarded a Multidisciplinary University Research Initiative (MURI) grant from the Air Force Office of Scientific Research (AFOSR) to study how different classes of mechanical metamaterials interact with dynamics of turbulent flows. Their findings are expected to result in transformative changes to the energy requirements and flight envelope of air vehicle operation, imperative to the sustainability and superiority of the Department of Defense (DoD) energy ecosystem.

The project, “Fluid‐Metamaterial‐Interaction to Revolutionize Passive Control of Aerodynamic Flows,” is a collaboration between fluids and structural mechanics experts to marry expertise in turbulent flow dynamics, fluid-structure interaction (FSI) and mechanics and manufacturing to enable an intelligent pairing of carefully chosen mechanical metamaterials with fundamental flows that embody key barriers to improved air vehicle flight.

Katie Matlack, Assistant Professor in the Department of Mechanical Science and Engineering at the University of Illinois Urbana-Champaign (UIUC), will lead the seven-person team, which includes UIUC Department of Aerospace faculty Andres Goza, Phillip Ansell and Theresa Saxton-Fox; Jordan Raney, Assistant Professor in Mechanical Engineering and Applied Mechanics in Penn Engineering; Jane Bae, Assistant Professor at Caltech; and Harold Park, Professor at Boston University.

Some mechanical metamaterials have complex responses to loads, including frequency-dependent responses, directionally dependent responses and the ability to respond differently depending on which global equilibrium point they start in. The researchers plan to use these advanced capabilities of metamaterials to couple to and modify complex and problematic fluid dynamic behaviors to improve the performance of advanced vehicles, including reducing drag and enhancing maneuverability.

“We intend to design metamaterial structures that autonomously change shape, texture or configuration in order to passively take advantage of flow changes,” says Raney. “Our role in the project will focus on the design, manufacturing and characterization of large-amplitude structural changes in response to changes in fluid loading.”

“Fluid-structure interaction is incredibly challenging,” he continues. “The challenges increase when the structures are metamaterials with very complex frequency- and amplitude-dependent responses.”

The team will establish a new multidisciplinary field – fluid-metamaterial interaction (FMI) – and aim to discover new fluid-structure coupling between innovative materials and critical aerodynamic flows to enable passive control of transition delay, drag reduction and separation.

The researchers’ expertise spans all areas of FMI: multiple classes of mechanical metamaterials, architected materials, advanced manufacturing, computational mechanics, FMI simulations, experimental turbulent dynamics, experimental fluid dynamics and turbulence modeling. Their work will introduce new engineering tools, including high-fidelity computational frameworks, reduced-order model paradigms, coupled experimental methodologies and manufacturing capabilities.

The FMI simulations discovered through this program are anticipated to produce transformative leaps in our scientific understanding of FSI. For the DoD, this work will result in surface/subsurface structural systems to make passive, dynamic flow control within next-generation air vehicles a reality.

“The most exciting work happens at the interfaces of multiple disciplines,” says Raney. “This project involves very difficult and disparate topics. Every member of this large team is absolutely necessary for us to be able to tackle these complex issues. I am excited to have the opportunity to work with them on problems that are at the forefront of aerospace research. This work really has the potential to make a practical difference in the next generation of aerospace vehicles.”

This announcement was produced in collaboration with Julia Park at the Grainger College of Engineering, University of Illinois Urbana-Champaign.