AEROSPACE ENGINEERING

Abstract

Nanomaterials are known to exhibit enhanced mechanical properties relative to their bulk counterparts. Materials have been made that incorporate these nanomaterials to achieve remarkable properties like high strength and low density, but the role of nanomaterials on toughness is not well understood. This talk will examine two classes of nanoarchitected materials – Bouligand polymer nanofibers (nano-Bouligand) and gradient spinodal ceramics – to illustrate the powerful role of nanomaterials and structural heterogeneity in
controlling toughness and recoverability. Single-edge notch fracture experiments were performed on
nano-Bouligand beams created using two-photon lithography. In this, it was found that:

1) enhanced plastic energy dissipation in isolated nanofibers allows 50% dense materials to achieve a comparable toughness to that of bulk materials, and

2) increasing nanoscale heterogeneity through interlayer twisting serves to further enhance toughness.

Compression and laser shock testing were performed on gradient alumina spinodal nanoarchitectures. In this, it was found that microscale structural heterogeneity can impede failure localization like shear banding and greatly enhance recoverability, even at high strain rates. These results demonstrate the remarkable toughness properties of nanostructured materials and reveal the potential for creating new nanoengineered materials with intrinsic mechanical resilience.

Speaker

Dr. Lucas Meza

Assistant Professor in Mechanical Engineering at the University of Washington. His research investigates new ways of engineering material properties at the micro- and nanoscale. He did his postdoc at the University of Cambridge, where he studied the micromechanical behavior of 3D woven fiber composites. He obtained his Ph.D. in 2016 in mechanical engineering from the California Institute of Technology (Caltech) for his work on ultralight, hierarchical metamaterials composed of nanoscale ceramics. His work is supported by the National Science Foundation and the Department of Energy.