Three-dimensional (3D) braided composites are a particular kind of composite materials characterized by yarns oriented not only in-plane, but also in the through-thickness direction. Thanks to this peculiar three-dimensional structure, these composites show outstanding mechanical properties making them excellent candidates for the lightweight components and structures of the future. Interesting examples of practical use of these materials include, but are not limited to automotive applications in which they can increase car crashworthiness while reducing weight and fuel consumption; wind energy technologies where their outstanding mechanical and fatigue resistance performances can lead to more durable and efficient turbine blades; and aerospace structural elements in which they can substitute metallic load bearing components. However, an efficient use of these materials has been limited by the lack of data characterizing their mechanical behavior as well as efficient computational tools for design. The overarching goal of this research project is to fill this knowledge gap by providing a comprehensive experimental characterization and by developing, calibrating and validating a multiscale numerical framework for the design of safe and efficient 3D braided composite structures. The technical tasks of the project will be complemented by a wide range of activities aimed at broadening the research impact on education, promotion of diversity, dissemination of results, and enhancing society benefits. These will include, but not limited to, group discussions with high school and graduate students; and visits to high-schools in the Chicagoland area.
The specific objectives of this research are to develop an innovative experimental protocol to characterize 3D braided composite fracture and to introduce an accessible, computationally efficient structural analysis tool for 3D braided composites to researchers and industry. The experimental campaign will address the problem of characterizing the softening behavior of composites and it will provide complete fracture data for model calibration and validation. The multiscale framework, calibrated and validated through the experimental investigations, will be used to gain understanding on the combined effect of the microstructure of the material as well as of structural size and geometry. Furthermore, this multiscale formulation will offer the ability to analyze different 3D braided architectures with much less experimental work, opening avenues for structural optimization. In addition, it will be able to capture the structural size effect that has been proven to affect composite material structures and it is usually overlooked by current design procedures.
