For my Masters Thesis I investigated the elastodynamic scattering by different types of inhomogeneities for use with ultrasonic nondestructive testing. This required writing and then running boundary element computer programs.
For my Ph. D. dissertation I investigated the possibility of using a fractal approach to describe the micromechanics of interfacial failure at contacting surfaces. This required developing analytical models to describe the normal and transverse deformations associated with the frictional contact of rough surfaces. Results from this analysis were then employed to model the fiber pullout problem associated with composite materials.
I spent several years working on the penetration of both ductile and geologic materials over a wide range of striking velocities. This work involved conducting laboratory scale material tests, penetration experiments, and then modeling the experimental results. Effective continua constitutive models were developed from experimental data to represent the large deformation and high strain-rate behavior of both the projectile and target materials. Next, we then modeled the penetration experiments by utilizing a three dimensional, explicit, transient dynamic, finite element code to model the projectile and an analytical forcing function derived from the dynamic expansion of a spherical cavity to model the target.
Most recently, I have been working on modeling the damage of carbon reinforced epoxy matrix composite materials that are to be used on the new Boeing 787 aircraft. This work involves constructing constitutive models for the composite materials used on the aircraft which are able to represent the damage caused by hail, birds, and other foreign object debris. This work has required implementing the non-ordinary state based peridynamic method in the Sandia National Laboratories developed lattice dynamics computer code EMU. Additionally, the Boeing Company developed strain invariant failure theory (SIFT) was implemented in the EMU lattice dynamics computer code for use with the non-ordinary state based peridynamic method.