In a Sept. 10 article in the journal Advanced Materials, the research team led by Reza Moini, an assistant professor of Civil and Environmental Engineering, and Shashank Gupta, a third-year Ph.D. candidate, demonstrate that cement paste deployed with a tube-like architecture can significantly increase resistance to crack propagation and improve the ability to deform without sudden failure. By proposing a statistical mechanics approach to quantify disorder in architected materials, the team have provided a pathway to quantify disorder in architected arrangements as described by Reza Moini and co‐worker.
The team was inspired by human cortical bone, the dense outer shell of human femurs that provide strength and resists fracture. Cortical bone consists of elliptical tubular components known as osteons, embedded weakly in an organic matrix. This unique architecture deflects cracks around osteons. This prevents abrupt failure and increases overall resistance to crack propagation, Gupta said.
“One expects the material to become less resistant to cracking when hollow tubes are incorporated,” Moini said. “We learned that by taking advantage of the tube geometry, size, shape, and orientation, we can promote crack-tube interaction to enhance one property without sacrificing another.”
The team discovered that such enhanced crack-tube interaction initiates a stepwise toughening mechanism, where the crack is first trapped by the tube and then delayed from propagation, leading to additional energy dissipation at each interaction and step.
The team have proposed a new framework that provides a more accurate representation of the material’s arrangements, moving towards a spectrum from ordered to random, beyond the simple binary classifications of periodic and non-periodic. Moini said that the study makes a distinction with approaches that confuse irregularity and perturbation with statistical disorder such as Voronoi tessellation and perturbation methods.
“This approach gives us a powerful tool to describe and design materials with a tailored degree of disorder,” Moini said. “Using advanced fabrication methods such as additive manufacturing can further promote the design of more disordered and mechanically favorable structures and allow for scaling up of these tubular designs for civil infrastructure components with concrete.”
The paper, “Tough Cortical Bone-Inspired Tubular Architected Cement-Based Material with Disorder,” was published on September 10, 2024 in Advanced Materials. Funding for the project was provided by the National Science Foundation CAREER Award (2238992) and the CMMI Division Grant (ECI, 2129566).
A public summary is released in the School of Engineering and Applied Sciences at Princeton about this article here.
