Research in Engineering Physics

Astronautics & Dynamics

Astronautics is the study of navigation outside of Earth’s atmosphere. Our faculty are actively involved in research in several sub-fields of astronautics, as described below. We also have several projects related to dynamics issues for aeronautics. Some of this is housed in the structural dynamics research group, as described below.

 

Research in Astronautics and Dynamics

Professor Matt Allen manages a variety of projects that combine experimental and analytical methods for dynamical systems. For example, he leads a project funded by the Air Force Office of Scientific Research that studies nonlinear vibrations in structural panels on hypersonic aircraft. He also has a project funded by the National Science Foundation to develop system identification techniques that determine the order, model form and parameters of nonlinear dynamic systems by approximating them as linear time-periodic over a certain limit cycle. These methods are being used to seek to obtain a better understanding of neuro-muscular function in human gait.

Professor Kammer studies the vibrations of a variety of structures, including the space shuttle and the space station, in order to facilitate vibration experiments on these structures and to identify damage before it becomes problematic. He applies a variety of strategies to pursue these outcomes, including optimal sensor placement, inverse methods for force identification, the remote sensing system for damage detection, and error propogation using metamodeling.

Professor Bonazza built and runs a vertical shock tube for studying the mixing of fluids as a shock wave encounters an interface between two fluids of different densities. These studies have application to inertial confinement fusion experiments (the implosion of a spherical shell containing fusion fuels) and supersonic combustion (where the shock-induced mixing produces more complete burning and thus reduces pollution).

Fusion Science and Technology

Fusion reactions combine light ions to produce heavier nuclei, along with energy associated with mass conversion. This energy can be converted to electricity, or the energetic particles can be used for non-electric applications. Faculty and staff in this area are exploring a variety of technologies for the production of fusion energy.

Research in Fusion Science and Technology

In magnetic fusion, an ionized gas, or plasma, is confined within a vacuum chamber by magnetic fields.  The department has two major fusion experiments, Pegasus, under the supervision of Prof. Fonck and Maria supervised by Prof. Schmitz.  There are two other major magnetic fusion experiments on the UW-Madison campus.  They are HSX, a stellarator, in the Department of Electrical and Computer Engineering and MST, a reversed-field pinch device, in the Department of Physics.

In addition to these magnetic fusion experiments, we have a robust theory and computation effort spearheaded by Professors Sovinec and Hegna , who use analytic and computational techniques to study the dynamics of high temperature plasmas.

In inertial fusion, lasers or ion beams are used to compress a small pellet filled with fusion fuels (usually deuterium and tritium). Professor Moses has extensive experience with radiation hydrodynamics simulations, permitting the study of both target implosions and the transport of the resulting energy to the walls of the surrounding chamber. Professor Bonazza uses a shock tube to study instabilities related to target implosions.

Fusion technology addresses the engineering issues that must be addressed to build a reactor capable of producing electricity from fusion. Professors Kulcinski, Moses, Blanchard, Henderson, El-Guebaly, Santarius, Sawan, and Wilson have active research programs to address such issues as heat removal, radiation damage to materials, tritium production, magnet design, neutron and gamma transport and component lifetime in such machines.

Inertial electrostatic confinement fusion employs potential differences across concentric, spherical grids to accelerate ions and produce fusion. Professors Kulcinski and Santarius head a team addressing a variety of technologies and applications suitable to this approach.

Mechanics of Materials

The Mechanics of Materials group at UW-Madison combines the study of mechanics (the study of forces, stresses, deformation and motion as applied to engineering structures) and materials science (the study of material development, fabrication, chemical composition, microstructure and properties) to study a wide variety of engineering problems. We merge these disciplines to dramatically enhance our capability both to understand and characterize existing materials and to invent exceptional new materials. The Mechanics of Materials group comprises six faculty members in the Department of Materials Science and Engineering and the Department of Engineering Physics. They have active programs in the following areas:

Research in Mechanics of Materials

In Professor Lakes‘ laboratory, he and his students synthesize and characterize novel materials for engineering applications. Materials that undergo phase transformation are of interest in the context of viscoelastic damping and of negative stiffness. They have developed new materials with reversed properties, including negative Poisson’s ratio, negative stiffness, and negative thermal expansion. Designed materials can have thermal expansion or piezoelectric sensitivity of arbitrarily large magnitude. Professor Lakes and his students have demonstrated, in the lab, composite materials stiffer than diamond over a temperature range.

Professor Drugan and his students collaborate with Professor Lakes on these projects as well, enhancing the understanding of the mechanics of these materials with illuminating theoretical models. In particular, they have developed models regarding the stability of materials with negative stiffness.

Professor Crone studies the response of stem cells to a surrounding three-dimensional hydrogel matrix. The objective of this research is to test the influence of hydrogel material properties and mechanical stimulation on the differentiation of stem cells. Hydrogels have been shown to have promise for a range of biomaterials and biomedical device applications, including cell scaffolding, artificial tissues, wound repair, drug delivery, and microfluidic devices. This work ultimately will impact the development of tissue-engineered constructs for cardiac repair.

Professor Crone also has projects related to biocompatibility of engineering materials. Biomedical devices such as stents and vascular grafts are often coated with various materials to prevent problems such as clotting around the instrument. Typically, the base material provides the desired mechanical properties while the coating provides biocompatibility. An alternative approach is to make the base material biocompatible. Our reach has focused on modifying the surfaces of nickel-titanium (NiTi) shape-memory alloys and developing polyurethane-based polymers that possess mechanical properties similar to the surrounding biological materials. Matching the mechanical properties (especially the stiffness) of the device to the surrounding structures results in better performance.

Professor Plesha and his students study discrete element methods (DEM), in which materials are modeled in a particle-by-particle manner. The technique is especially effective for applications to particulate materials, such as soil and powder, but is also applicable to modeling solids and the degradation of solids into particulates. At UW-Madison, we are involved with developing new enhancements to DEM, such as clustering to model particles of arbitrary rough shape, megaclustering to model solids and damage of solids, and development of new time integration methods to allow for more rapid computing.

Professor Drugan is an international expert in theoretical fracture mechanics. He has carried out numerous studies of fracture in ductile materials, dynamics fragmentation of bodies absorbing energy over very short time scales, and nanoscale fracture (often governed by the mechanics of individual defects).

Nuclear Systems Engineering

The United States has about 104 commercial fission reactors producing approximately 19% of our electricity. Our nuclear systems engineering research programs are largely devoted to advancing the state of the art in technologies used to produce electricity from fission. Some of our key programs are described below.

Research in Nuclear Systems Engineering

If we are to have a viable commercial nuclear energy fleet, we must be able to understand the behavior of a reactor under all operating conditions. Professors Corradini, AndersonBonazza, and Scarlat have extensive experience modeling reactors from a safety perspective as well as in experiments for validating the models.

The neutrons and charged particles inevitably present in nuclear facilities can do significant damage to structural materials. Atoms are displaced, properties are modified, and structures are deformed. We must understand these phenomena in order to produce viable reactor designs and understand component lifetime issues. Professors AllenKulcinski, Blanchard, Sridharan, CouetSzlufarska, and Morgan have experimental and computational programs to study the physics of these radiation damage events and the subsequent effect on reactor design.

As simulation takes a larger role in the development of nuclear technology, there is a need to improve the fidelity and complexity of the simulations. With a focus on radiation transport and nuclide inventory tracking — and coupling these to other domain physics — Professors WilsonHenderson, and Tautges are delivering new simulation capability by combining modern computational science technology with new solution methodologies. These tools are being used to design complex systems like ITER, to improve radiation treatment planning, to understand next generation reactor designs, and to explore the science-policy boundary of advanced fuel cycles.

As we look to the future, reactors will tend to operate at higher temperatures in order to increase the efficiency of the energy conversion processes or to produce process heat for industrial applications such as hydrogen production. This leads us to the use of new coolants and materials and the need for ensuring that these combinations are compatible. Professors Allen, Sridharan, Anderson, and Couet all operate a variety of experiments that test the compatibility of coolants such as lithium, lead and aqueous salts with new, high temperature structural materials.

Radioisotope power sources convert the energy released during radioactive decay into electricity. Pacemakers were made years ago using this technology, in order to take advantage of their long lives and avoid the surgery needed for battery replacement. NASA also uses such sources in its space probes, in order to permit long, unattended missions. Professors Blanchard and Ma have studies several concepts for the production of modern nuclear batteries.

Research centers, consortia, and laboratories