Xiaoyu (Rayne) Zheng (Advisor)

The rapid development of additive manufacturing technologies has enabled the fabrication of truss metamaterials, i.e., a novel class of lightweight-yet-strong materials with engineered complex hierarchical structures. Manipulating the architecture over chemical composition dramatically expands the achievable materials design space, allowing to largely control the mechanical response of metamaterials. Despite the great advances made in this area, designing three-dimensional (3D) truss metamaterials under complex or extreme conditions with programmable response is still a...

The performance of ultrasonic transducers is largely determined by the piezoelectric properties and geometries of their active elements. Due to the brittle nature of piezoceramics, existing processing tools for piezoelectric elements only achieve simple geometries, including flat disks, cylinders, cubes and rings. While advances in additive manufacturing give rise to free-form fabrication of piezoceramics, the resultant transducers suffer from high porosity, weak piezoelectric responses, and limited geometrical flexibility. We introduce optimized piezoceramic printing and...

The orientation of fibrous fillers, induced by shear forces during extrusion, has been demonstrated to significantly enhance mechanical properties, electrical/thermal conductivity, microwave attenuation etc., albeit primarily in a two-dimensional (2D) x-y plane. In this study, we present a novel approach for achieving fiber alignment in a three-dimensional (3D) context, with an emphasis on the Z-direction, by utilizing embedded 3D printing techniques. This process involves the extrusion and suspension of composite inks within a viscoelastic gel medium, during which the...