Active research projects in the microMechanics of Deformation Group include:
Mechanics of dislocation cell walls
In heavily deformed metals, dislocations arrange themselves into intricate, cellular patterns (see TEM image to the right, courtesy D. L. Medlin). It has been a long-standing theoretical quandary why dislocations would form such ordered networks rather than random jumbles. The goal of this project is to couple discrete dislocation dynamics simulations with three-dimensional electron tomography to gain insight into what stabilizes the walls of cellular dislocation structures.
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.
Engineering damage tolerant composite laminates
Fiber-reinforced polymer composites are known to exhibit poor damage tolerance; a service accident (e.g., tool drop) can result in sub-surface impact damage that is barely visible and deleterious to structural performance. The PI has recently invented a technique for promoting damage tolerance through heterogeneous interlaminar toughening. This project is focused on using finite element simulations of interlaminar fracture to apply the new technique in laminate design.
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 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.