EPSCoR Research Fellows: NSF: Development of Characterization Techniques to Determine Rate and Temperature Dependent Composite Material Properties for the LS-DYNA MAT213 Model

This project would provide a fellowship to an Assistant professor at the University of Alabama Huntsville to study polymer matrix composite (PMC) materials. PMC materials are strong, lightweight, and corrosion-resistant. This makes them highly desirable as structural materials for use in aerospace, automotive, and maritime applications.

The weight reduction from using PMCs would result in increased fuel efficiency, reduced emissions, wider spread adoption of electric vehicles (EVs) by enabling longer driving range per battery charge, and implementation of electric vertical takeoff and landing (eVTOL) aircraft for applications such as urban transport and air taxis. However, a key limitation preventing the widespread use of PMCs is their complicated deformation and fracture behavior.

Existing testing and analysis methods are unable to accurately predict how PMCs will respond during dynamic vehicle crashes and high-speed impacts such as aircraft bird strike incidents. This makes it impossible to guarantee the safety of the vehicle occupants if PMC components are used. This project aims to resolve this problem by developing the experimental and computer modeling techniques necessary to accurately predict the dynamic fracture and deformation behavior of PMCs, through a cooperative effort between the PI and the researchers at the NASA Glenn Research Center.

This will enable the widespread adoption of PMCs for use in these critical safety applications, and help revolutionize the transportation industry.

PMCs are highly anisotropic and exhibit multiple possible failure modes such as fiber breaking, matrix cracking, and matrix-fiber delamination. Additionally, PMC materials exhibit changes in the stress vs. strain behavior and fracture response when subjected to high-rate loading. To add further complexity, PMCs experience highly localized temperature increases during high-rate loading that can approach or exceed the glass transition temperature of the polymer matrix.

This can result in significant changes to the material strength and ductility during high-rate loading compared to loading at low rates. This complex thermo-mechanical behavior will be investigated experimentally through the use of novel Mode I and Mode II dynamic fracture tests, ballistic impact tests, and dynamic crush tests on full-scale PMC components.

These tests will be coupled with full-field digital image correlation and high-rate thermal imaging to capture the localized deformation, strain, and temperature increases. This data will be used to construct rate- and temperature-dependent deformation and fracture models implemented within the finite element analysis software LS-DYNA. The testing methodology and analytical techniques developed through this project will enable accurate simulations of PMCs to be performed, allowing for the design of PMC components that are capable of safely withstanding crash and impact events.

Additionally, the insights gained through this project will enable a greater understanding of the fundamental mechanisms behind PMC deformation and fracture behavior, allowing for more informed design of novel PMC materials with enhanced performance.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.