Mechanics and Materials

Arruda's Group: Mechanical Behavior of Materials Lab
The focus of our research is to investigate the various toughening mechanisms in polymer nanocomposites at low and high strain rates. The development of these nanocomposites is approached using a manufacturing technique called layer-by-layer (LBL) manufacturing. The LBL manufacturing involves the sequential adsorption of layers of oppositely charged macromolecules that may include polyelectrolytes, nanowires, clay nanoparticles, proteins, DNA, dyes and other materials. We focus on clay nanoparticles reinforced polymer nanocomposites. Shown below is an image of a (poly)vinyl alcohol-clay nanocomposite with 50 volume % of clay nanoparticles prepared using the LBL technique.

Daly's Group
The research activities of the Daly group focus on the application of multi-scale experimental mechanics to materials science in order to characterize, design and develop new materials. Specific interests of the group include microstructural features of materials; effect of microstructure on macroscopic properties; deformation mechanisms of biomaterials; material behavior at the nanoscale; fracture and failure mechanisms; novel methods of multi-scale material characterization; active materials; and plasticity and phase transformations. The Daly group is particularly interested in the behavior of and interaction between material features on different length scales, which play a large role in important processes like fatigue and failure. Understanding the complex relationship between the nano- and micro- scale behavior of a material and its macroscopic properties is a critical aspect of the development of new materials and the accurate prediction of their behavior in practical applications.

Wineman's Research
This figure shows results of an experiment that illustrates the phenomena being modeled. A rubber strip was subjected to a step stretch history with stretch ratio (green curve). The temperature T was held fixed at 25o C for 3 hours, then rapidly increased to 125o C and held constant (red curve). The force per original cross sectional area (engineering stress) was measured (blue curve). The force curve shows three distinct phenomena, (i) viscoelastic stress relaxation at 25o C during the first 3 hours, (ii) entropic stiffening occurring during the rise in temperature to 125o C followed by (iii) scission based stress relaxation.

John Hart's research deals with manufacturing and applications of nanostructured materials. His group seeks to expand the science of synthesizing these materials and engineering their fundamental properties; to create new technology to control the related chemical, mechanical, and thermal assembly processes; and to pioneer applications which harness the unique properties of nanostructures at small and large scales. Examples of science include studies of the growth mechanism of nanowires and nanotubes by chemical vapor deposition; examples of technology include machines for growth of long nanostructures and large-area aligned films of nanostructures; and examples of applications include chemical sensors, energy-efficient actuators, and structural composites. (Mechanosynthesis Group)

Garikipati's Research: Computational Physics Group
The Computational Physics Group develops theory and numerical methods for coupled physical phenomena spanning mechanics, thermodynamics, transport, reactions and phase transformations. We focus on problems in biology and materials physics, and draw heavily from the methods of applied mathematics and numerical analysis.