Research

Research topics of interest:

Multiscale materials modeling: atomistic (classical molecular dynamics), mesoscale (discrete dislocation dynamics, Monte Carlo, phase field, lattice Boltzmann), macroscale (finite element methods)

Fracture and toughening: ductile fracture of metals; intergranular fracture; fracture in laminated composites; fracture and toughening in ceramics; cohesive zone/surface modeling

Crystal plasticity: dislocation-based, twinning-induced, and transformation-induced plasticity; hardening and strengthening mechanisms, including strain, precipitation, and solid solution strengthening

Hydrogen and helium embrittlement: helium bubble formation, growth, migration, and rupture; hydrogen-defect interactions; helium-defect interactions; grain boundary fracture; embrittlement of structural stainless steels

Crystalline interfaces: atomic structure of interfaces; interfacial line defects (dislocations and disconnections) and interactions with bulk dislocations; interfacial migration; grain boundary phases/complexions; fracture of interfaces

Analysis of atomistic simulations: identification of interfacial line defects (published a tool called ILDA); machine-learning-based atomic structure analysis (developing a tool called ATOMIC); collaboration with OVITO

Neural-network-based surrogate modeling: physics-informed neural networks; equivariance; coupling neural networks with the finite element method; encoder-decoder architectures

Fluid-particle systems: packing of particulate/granular systems; pore size distribution and analysis; fluid-particle interactions; colloidal suspensions; particle-laden emulsions; fluid phase separation

Sample projects (past and current):

Finite-element-based neural network surrogate models

Surrogate models provide accurate solutions to problems in science and engineering at a fraction of the computational time. Our group has recently developed a technique for training neural networks using the finite element method (patent pending), so that surrogate models can be easily developed using existing finite element codes.

Funding: National Science Foundation, Rutgers TechAdvance

Micromechanics of void nucleation

Most ductile metals (e.g., steels, aluminum alloys) fail when small voids nucleate and grow to coalescence. This project is focused on using molecular dynamics simulations and machine learning (in collaboration with Prof. Aziz Ezzat of ISE) to study the micromechanics of void nucleation at small particles. The goal is to use these simulations to develop a micromechanically informed theory for void nucleation and damage.

Funding: National Science Foundation, Sandia National Laboratories

Micromechanics of Migrating Interfaces

Interfaces such as grain and phase boundaries are ubiquitous in materials. And yet, the mechanics by which they migrate are poorly understood, making it difficult to predict material behaviors and design advanced materials. The goal of this project is to reveal line-defect-based mechanisms of migration and develop physics-based, predictive models for interface migration.

Funding: Department of Energy – Office of Science

Dislocation network theory of plasticity

The mechanical behaviors of most metals are governed by the evolution of dislocation network structures. However, existing models for predicting deformation and damage in metals largely neglect the dislocation network. The goal of this project is to develop a new theory that captures evolution of the dislocation network in precipitation strengthened metals to provide a physics-based plasticity modeling framework.

Funding: Army Research Office, Naval Nuclear Laboratory

Hydrogen-affected crack initiation in metals

Under fatigue loading, cracks often initiate at microstructural features, such as twin boundaries (as shown in the image to the right, courtesy C. W. San Marchi) and deformation-induced phases. The microstructural conditions which drive these initiation events are poorly understood, however. The goal of this project is to utilize multiscale materials modeling to better understand how defect interactions can drive crack initiation in hydrogen-affected metals.

Funding: Sandia National Laboratories

Formation of microporous networks

In collaboration with Prof. Jon Singer of MAE, we are simulating the formation of microporous nanocomposite emulsion thermosets (MINETs), a highly tunable class of microporous composites recently developed by Prof. Singer’s group. The composites are produced by mixing oil, epoxy, surfactant, and nanoparticles, and then rinsing out the oil phase after the epoxy has cured. Our goal is to understand the mechanisms and scaling behaviors underlying the formation of these microporous networks.

Toughening in ceramic composites

Ceramics are ideal structural materials in all ways except one: they are brittle and flaw intolerant. The goal of this research, in collaboration with the Riman Group, is to determine optimal designs for ceramic composites which enhance toughening to reduce brittleness.