Research
-
Mechanics and Materials
The materials and solid mechanics faculty in Mechanical Engineering are a diverse group of experimentalists, theoreticians and computational experts. We work on many cutting edge problems, and some long-standing classical problems, drawn from materials physics (broadly defined), biology and automotive engineering. The following link leads to very brief outlines of the research that drives us.
-
Research Highlights
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.
Currently, we are focusing on the structural, thermal and mechanical characterizations of Polyurethane-clay nanocomposite system. These characterizations involve the use of several robust equipments such as MTS servo hydraulic test system, in-house built tensiometer, dynamic mechanical analyzer, split-Hopkinson pressure bar setup, Perkin-Elmer differential scanning calorimeter, scanning electron microscope, atomic force microscope, transmission electron microscope, thermogravimetric analyzer and wide angle X-ray scattering setup.Using this system, we demonstrate that by reinforcing the polyurethane with an optimum volume % of clay nanoparticles, it is possible to design materials with enhanced mechanical properties ranging from tough nanocomposite to stiff and strong nanocomposite (refer Figure 2).
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.
This figure shows a simply supported beam under a uniform load distribution that varies sinuoidally with time. The beam is made of a polymer, modeled as a linear viscoelastic material. Such materials dissipate energy that is converted to heat. Polymers are poor conductors of heat and so there will be an increase in temperature in the beam. The work per cycle has been calculated and plotted versus beam location. The maximum work per cycle occurs at the top and bottom of the middle cross section. It can be expected that there is a significant temperature increase at these locations, followed by polymer degradation that results in material softening and the formation of a 'degradation'-like hinge, that is, a region of high local curvature leading to large deflections and eventual collapse.Hart's Research: Mechanosynthesis Group
Carbon nanotubes
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.
Researchers
Mechanics of polymers and soft biologial tissue, tissue engineering and rehabilitation
Contact mechanics, thermoelasticity, elasticity theory
Samantha Daly Active materials and composites, fracture and failure mechanisms, plasticity, phase transformations
Computational mechanics, mechanics soft biological tissue and growth, mechanics of semiconductors
Manufacturing and applications of nanostructured materials, including nanotubes and nanowires
Computational mechanics and dynamics, homogenization design
Computational mechanics, structural design optimization
Modeling and simulation of nano-microstructure
laser aided manufacturing
Toughening mechanisms in ceramics and polymer composities
Numerical and experimental work in disordered materials systems, design of batteries
Micromechanics modeling of materials
Mechanics of continua including nonlinear elasticity and viscoelasticity of polymers