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Wisconsin Distinguished Professor, Department of Engineering Physics , Engineering Mechanics Program, Biomedical Engineering Department, Materials Science Program, Rheology Research Center, and Mechanics and Materials Group University of Wisconsin 541 Engineering Research Building (ERB), 1500 Engineering Drive, Madison, WI 53706-1687 Phone (608) 265-8697, Fax (608) 263-7451, e-mail
Research summary
We study materials with heterogeneous structure, including natural viscoelastic composites such as bone, ligament, tendon and wood, as well as synthetic composites, biomaterials, and cellular solids with structural hierarchy. We investigate the freedom of natural and synthesized materials to behave in ways not anticipated in elementary continuum representations, and to attain physical properties of much higher magnitude than anticipated from standard theories. Viscoelastic materials are of particular interest as high performance damping materials and as materials which undergo creep in industrial settings. We determine viscoelastic properties including internal friction and creep over eleven orders of magnitude of frequency and time, with no need for temperature shifts. In our laboratory we synthesize and characterize materials with extreme and unusual physical properties. Materials which undergo phase transformation are of interest in the context of viscoelastic damping and of negative stiffness. We 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. Composite materials stiffer than diamond over a temperature range have been demonstrated. We pursue basic research as well as applied research for industry. |
