Composite Materials: Carbon fiber reinforced polymer composites are used in airplanes, sailboats, cars, wind turbines, sport equipment, and many other structures where high strength-to-weight ratios are required. Delamination is a predominant failure mechanism these composites.  Applying fracture dynamics in finite elements simulations we help to design composite materials that reduce the formation of extensive delamination zones.

Alloys and high entropy alloys: Alloys and high entropy alloys exhibit superior functional properties. We develop predictive models of flow, strengthening, ductility, and fatigue, to advance the design of alloys by selecting the composition required to achieve a specific purpose. 

Energetic Materials: Detonations in energetic materials can initiate from shock loading through a combination of chemical, thermal, and mechanical processes. The presence of microstructural defects like cracks, voids, grain boundaries, and interfaces are initiation sites for the formation of hot-spots that precede detonation. We incorporate these defects explicitly to predict ignition due to shock compression. The characteristic length of these defects is at submicron or micron scale. While transition to detonation occurs at millimeter scales. To ensure computational efficiency, we develop high-fidelity surrogate models informed from microscale simulations and we use them in detonation simulations.

Camilo A. Duarte, Chunyu Li, Brenden W. Hamilton, A. Strachan, and Marisol Koslowski, Continuum and molecular dynamics simulations of pore collapse in shocked β- tetramethylene tetranitramine single crystals, Journal of Applied Physics, 129 015904, 2021.
Sakano, Michael; Hamed, Ahmed; Kober, Edward; Grilli, Nicolo; Hamilton, Brenden; Islam, Md Mahbubul; Koslowski, Marisol; Strachan, Alejandro, Unsupervised learning-based multiscale model of thermochemistry in RDX, Journal of Physical Chemistry, 124 44 9141-9155, 2020.
Camilo A. Duarte, Ahmed Hamed, Jonathan D. Drake, Christian J. Sorensen, Steven F. Son, Weynong W. Chen, and Marisol Koslowski, Void collapse in shocked beta-HMX single crystals: simulations and experiments, Propellants, Explosives, Pyrotechnics, 45(2) 243-253, 2020.

Expounding upon previous work, we have created a finite deformation model that contains crystal plasticity, fracture, and a MieGrüneisen equation of state. We apply this model to HMX to study the influence of pore collapse and fracture of low velocity impacts to study accidental initiation of energetic materials. We study the influence of crystal orientation, impact velocity, and pore geometry on crack growth.

Periodic excitation of energetic materials: Polymer bonded explosives (PBXs) are composite materials containing energetic particles in a polymeric binder that are designed to react under a controlled stimulus. Accidental ignition followed by initiation may occur when a PBX sample is subjected to mechanical impact or vibration. We use finite element simulations to predict the damaging effect of ultrasonic vibration in PBX microstructures that can affect the ignition threshold of these composite materials.

Reliability of Microelectronics: Of the many lead-free solders used in the semiconductor industry, Sn-Ag-Cu (SAC) has emerged as one of the most accepted. However, the interfacial reaction of Cu with molten Sn-based solder results in the formation brittle intermetallic compounds (IMC) that accelerate the degradation of these systems_. In addition, electromigration is a concern due to the miniaturization of solder joints. We develop models and simulations  to predict the formation and evolution of IMCs, the nucleation of voids and the diffusion of copper due to electromigration.

Dynamic Response of Materials: We use finite elements simulations to study the response of materials under extreme conditions such as high strain rate impact and shock loading. The simulations include anisotropic crystalline plasticity, fracture, friction, and thermal response.

Nicolo Grilli and Marisol Koslowski, The effect of crystal anisotropy and plastic response on the dynamic fracture of energetic materials, Journal of Applied Physics, 126 155101, 2019.

Stress relaxation in thin films: Whiskers sometimes grow from surfaces of thin films reaching lengths of several micrometers and may cause electronic system failures such as short circuits when they bridge closely-spaced circuit elements.  Whiskers and hillocks appear to be responses of thin metal films to residual stresses but a single explanation to the operation of these phenomena has not been established. Finite elements simulations and experiments help to explain these mechanisms where grain orientation and recrystallization play a key role.