Research in Engineering Physics

Aerospace & Dynamics

Our faculty are actively involved in research in several sub-fields of aerospace engineering. 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 Aerospace and Dynamics

Professor 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.

In the Wisconsin Shock Tube Laboratory, Professor Bonazza and his group investigate the flow induced by the interaction of a shock wave with the interface between gases of different densities, involving shock refraction, mixing and turbulence.

This kind of flow occurs in inertial confinement fusion experiments (the implosion of a spherical shell containing fusion fuels) and supersonic combustion systems (where the shock-induced mixing is postulated to promote the occurrence of chemical reactions over very short times).

Professor Jen Franck uses computational tools to investigate the dynamics and physics of unsteady, turbulent flows. Her lab utilizes a range of computational techniques, including Direct Numerical Simulation (DNS), Large-eddy simulation (LES) and Reynolds-Averaged Navier-Stokes (RANS) solvers. These solvers are applied to fundamental problems in fluid mechanics and in applications areas such as aerodynamic flow control, wind/tidal energy, propulsion or flapping flight.

Professor Choy’s research group develops quantum instruments based on atoms and atom-like systems for precise inertial sensing and timekeeping. Research interests in this area include advanced accelerometers and gyroscopes with improved positioning accuracy, precise and stable time and frequency standards, and the application of quantum sensors to navigate using maps of local gravity and magnetic variations.

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 Emeritus Professor Fonck and Maria supervised by Professor 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.

Fusion technology addresses the engineering issues that must be addressed to build a reactor capable of producing electricity from fusion. Professors Blanchard, Henderson, 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.

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 seven 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

Professor Thevamaran’s laboratory focuses on advancing the fundamental knowledge of process-structure-property-function relations in structured materials and creating innovative structured materials with extreme mechanical properties. He studies a variety of advanced materials from hierarchical carbon nanotube foams and gradient-nano-grained metals to non-Hermitian metamaterials.

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 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 Notbohm studies mechanics of biological fibrous materials, cell-matrix interactions, and collective cell migration.

Nuclear Systems Engineering

The United States has about 100 commercial fission reactors producing approximately 19% of our electricity and over 50% of our low-emission 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 and strive to continue to improve upon efficiency, safety, economics and performance of nuclear reactors we must be able to understand the behavior of a reactor under all operating conditions. Professors Corradini and Anderson have extensive experience modeling reactors and reactor components from a fluids, heat transfer and thermodynamics perspective as well as conducting experiments that validate the models.

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 Wilson and Henderson 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.

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 Blanchard, Sridharan, Couet, Zhang, Szlufarska, and Morgan have state of the art experimental and computational research programs to study the physics of these radiation damage events and the subsequent effect on reactor design, with the objective to design fuels and structural materials that can (i) improve the economics and safety of current nuclear reactors and (ii) withstand the irradiation damage in advanced nuclear reactors.

Materials used in nuclear reactors are subject to intense irradiation which can induce severe property degradation such as hardening, embrittlement and reduced resistance to stress corrosion cracking, affecting reactor safety and economics. Use multiscale modeling and simulation, Professor Zhang studies the changes of microstructure and composition in nuclear materials caused by irradiation and the consequent degradation in mechanical properties. The topics of interest include primage damage production, defect self-organization, radiation-induced precipitation, and radiation enhanced and induced precipitation. The research outcome will help predict the degradation rates of material properties in current light water reactors and help develop advanced materials for future reactors.

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, such as molten salts, liquid metals and high-temperature gas, and materials and the need for ensuring that these combinations are compatible. Professors Sridharan, Anderson, and Couet all operate a variety of experiments that test the compatibility of coolants such as high temperature pressurized water, molten salt (fluorides and chlorides), lead and liquid metals (sodium and lead) with innovative, high-temperature structural materials.

Many advanced nuclear fuel cycles rely on technologies that could be diverted for non-peaceful applications.  Designing safeguards for declared facilities and detection mechanisms for undeclared facilities can help support an international nuclear non-proliferation regime that has been largely successful at stemming the expansion of nuclear weapons. Professor Wilson uses a combination of modeling, simulation, and data science to better understand the opportunities to secure advanced nuclear fuel cycle facilities of the future.

Advanced Detection and Measurement

The ability to precisely determine physical quantities is a critical functionality in many research areas in science and engineering. At the Department of Engineering Physics, advanced measurement tools are developed and applied to study plasma behaviors, properties of nuclear and structured materials, shock wave dynamics, and biological systems. Meanwhile, quantum physics and phenomena are used in the development of precision sensors that detect magnetic fields and inertial forces with unparalleled precision and accuracy, as well as sensitively measure changes in electromagnetic fields and temperature with nanometer-scale resolution.

Advanced Detection and Measurement

The underlying basis in quantum sensing is the discrete nature of electron energies in atoms, ions, or atom-like systems in solids. Each allowed electron energy state, and transition between energy states, corresponds to a characteristic frequency. Measurement of this frequency can allow us to tell time (in the case of atomic clocks) and infer small physical changes in the environment (such as electromagnetic fields, inertial forces, pressure/strain, temperature). Professor Choy’s research group is characterizing and developing quantum sensing platforms based on neutral atoms and optically-active spin defects in diamond.

Professor Choy’s group is also interested in applying nanoscale optics to improve photon detection and miniaturize optical systems in classical and quantum sensors. Moreover, since preparation and measurement of quantum systems rely on their interactions with photons, robust approaches to control photon properties are critical to the utility and performance of quantum devices.

Research centers, consortia, and laboratories