Opportunity at National Institute of Standards and Technology (NIST)
Dynamic Mechanical Property Measurements of Metals, Ceramics, and Polymers Using Novel Kolsky Bar Techniques
Material Measurement Laboratory, Materials Science and Engineering Division
Please note: This Agency only participates in the February and August reviews.
|Steven Paxson Mates
The mechanical behavior of metals, ceramics, and polymers under dynamic loading tends to differ, often significantly, from static loading behavior. The Kolsky Bar, also known as the Split Hopkinson Bar, is a common technique for studying the high strain rate behavior of materials. Novel improvements to this technique include the use of direct electrical pulse heating to probe the effects of high temperature and rapid heating rate on the dynamic flow stress of metals, and the real-time measurement of surface deformation using high speed Digital Image Correlation (DIC) to study the non-equilibrium dynamic response of soft polymers and to explore non-uniaxial stress and strain states by testing novel sample geometries that otherwise could not be effectively analyzed. DIC data are combined with finite element modeling to analyze non-uniform stress and strain states within samples during dynamic loading, and in some cases to deduce material property data, as defined by a pre-determined constitutive model, using inverse methods. Microstructural characterization using SEM, TEM, x-ray, and neutron scattering is applied when appropriate to identify and explore deformation mechanisms and establish structure-property relationships for materials subjected to dynamic mechanical and thermal loading.
Digital image correlation; Electrical pulse heating; Finite element modeling; High strain rate; Kolsky bar;
Open to U.S. citizens
Open to Postdoctoral applicants