Our research focuses on problems in theoretical and applied mechanics of solids, in the presence and absence of pore fluids, with special emphasis on fracture, deformation and wave propagation. Currently, we have three major research thrusts:
Mechanics and Physics of Earthquakes and Granular Materials:
The long term objective of this research is to link small scale processes in fault zones with large scale dynamic rupture characteristics, wave propagation, seismic and aseismic slip, and long term earthquake cycle models to provide rigorous predictive tools for nonlinear fault dynamics that can ultimately inform next generation seismic hazard models. Our work is contributing to the development of micromechanical models of deformation and failure in granular materials, modeling dynamic ruptures in heterogeneous fault zones and branched fault systems, identification of hydro-thermo- mechanical weakening mechanisms specific to fault gouge, investigation of strain localization and stick-slip dynamics in sheared and vibrated granular layers with breakable particles, and establishment of novel hybrid numerical techniques for multi-scale fault zone dynamics.
Mechanics and Physics of Networked and Biological Materials:
The long term objective of this research is to develop a rigorous understanding for the effect of micro-structure and local topology on deformation and failure of networked materials. Specific systems of interest include polymer networks as arising in hydrogels and soft tissues and trabecular networks in human bone. Current efforts focus on multi-scale constitutive modeling and fracture in soft materials including rate dependence, damage evolution, poro-mechanical effects and structure-function relations as well as the development of quasi-continuum models for domain decomposition in fractured lattice-like materials.
The primary objective of this research is to design materials with adaptive, tunable and extreme elastodynamic properties using principles from biology and geophysics that will transform applications in impact resistance, wave modulation, and earthquake engineering. Current efforts focus on theoretical understanding of the nature of mechanical band gaps, elastodynamic response of layered systems, novel applications of transformation elastodynamics, and modeling of negative stiffness structural elements.
To address these challenging topics we use a variety of theoretical techniques stemming from non-equilibrium statistical thermodynamics (shear transformation zone theory), computational mechanics (finite element and boundary integral methods), optimization theory (topology optimization), machine learning, and nonlinear dynamics (stability analysis, reduced order models and chaos theory).