Gao research group in Mechanical Engineering at The University of Texas at San Antonio works in the interdisciplinary field across solid mechanics, materials science and applied physics, with the main focuses on atomistic and multiscale materials modeling as well as nanomechanical experimentation. Our goal is to understand the fundamental principles governing mechanical behaviors of materials, including structural, functional and biological materials. Our research has plentiful applications in nanotechnologies, biomedicine, energy and others.

Research Highlights 

Phase Transition in 2D material: Monolayer MoTe2 exhibits two stable structural phases: semiconducting 2H phase and metallic 1T′ phase. This study quantitatively elucidates the atomistic, thermodynamic and kinetic mechanism of the phase transition under applied stress. The results shed light on the phase engineering of 2D TMD materials with stress at the atomic level (EML, 2020).

FD-NEB Method: A finite deformation Nudged Elastic Band method is developed to determine the pathway of a solid-solid transition process subjected to external stress fields.  It provides more accurate prediction for minimum energy path as compared to previous methods when solids undergo large deformation during transitions (J. Chem. Phys, 2019).

FD-Bell Theory: Stress can be applied to modulate solid–solid phase transitions because the stress changes the transition energy barrier which determines the phase transition rate. The lower the barrier, the higher the rate and more likely the phase transition occurs. This study presents a new theoretical method – finite deformation Bell theory, for predicting transition barriers as a function of the applied stress field (JMPS, 2020). 

Nanowire's Brittle-to-ductile Transition: The mechanical behavior of nanomaterials under high strain rates is critical to understand their suitability for dynamic applications. In this study, silver nanowires are in situ tested inside scanning electron microscope at strain rates up to 2/s. A brittle-to-ductile failure mode transition was observed at a threshold strain rate of 0.2/s (Nano Letters, 2016).

Deciphering Beetle Exoskeleton: One of the common architectures in natural materials is the helicoidal (Bouligand) structure, where fiber layers twist around a helical screw. In this study, nanomechanics is used to identify the geometry and material properties of the fibers that comprise a beetle's exoskeleton. This work could guide the design and manufacturing of new and improved artificial materials through bio-mimicry (Adv. Fun. Mater., 2017). 

Graphene's Entropic Elasticity: One-atom thick graphene displays significant thermal rippling at finite temperatures. In this study, both statistical mechanics and molecular dynamics simulations suggest considerable entropic contribution to the thermomechanical properties of monolayer graphene (JMPS, 2014).