Current projects:

I work on several projects as part of the Structural and Applied Mechanics Group within the Computational Engineering Division. As a mechanical/structural analyst, most of my projects involve simulating materials and structures undergoing large deformation and high strain rates due to blasts and impacts and analyzing the results. I work mainly with LLNL’s Arbitrary Lagrangian Eulerian code, ALE3D. In particular, I am involved with incorporating and validating new material models in the code (e.g. polymer and biological materials) as well as incorporating additional physics. Another aspect of my work involves collaborating with scientists and engineers in the Department of Defense to facilitate the use of ALE3D for their applications. As part of this project, I work with machine learning folks at LLNL to develop tools that facilitate the use of ALE3D by non-experts.

Experience:

• Mechanical/Structural Analyst, Computational Engineering Division, Lawrence Livermore National Laboratory (2019-present)
• Assistant Professor, Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology (2015-2019)
• Summer Faculty Fellow, Air Force Research Laboratory, United States Air Force Academy (2018)
• Summer Faculty Fellow, Air Force Research Laboratory, Edwards Air Force Base (2016)

Ph.D. Aeronautics, California Institute of Technology (2015)

M.S. Aeronautics, California Institute of Technology (2011)

B.S. Aerospace Engineering, University of Illinois at Urbana-Champaign (2010)

W. K. Hays, C. S. Wojnar: Dynamic electromechanical characterization of ferroelectrics at cryogenic temperatures. Exp. Mech. 58 (2018), 893-907.

T. C. Miller, C. S. Wojnar, J. A. Louke: Measuring propellant stress relaxation modulus using a dynamic mechanical analyzer. J. Propul. Power 33 (2017), 1252-1259.

C. S. Wojnar, D. M. Kochmann: Linking internal dissipation mechanisms to the effective complex viscoelastic moduli of ferroelectrics. J. Appl. Mech. 84 (2017), 021006

J.-B. le Graverend, C. S. Wojnar, D. M. Kochmann: Broadband Electromechanical Spectroscopy (BES): Measuring the dynamic mechanical response of viscoelastic materials under temperature and electric-field control in a vacuum environment. J. Mater. Sci. 50 (2015), 3965-3984.

C. S. Wojnar, J.-B. le Graverend, D. M. Kochmann: Broadband control of the viscoelasticity of ferroelectrics via domain switching. Appl. Phys. Lett. 105 (2014), 162912.

C. S. Wojnar and D. M. Kochmann: A negative-stiffness phase in elastic composites can produce stable extreme effective dynamic but not static stiffness. Philos. Mag. 94 (2014), 532-555.

C. S. Wojnar and D. M. Kochmann: Stability of extreme static and dynamic bulk moduli of an elastic two-phase composite due to a non-positive-definite-phase. Phys. Stat. Solidi B 251 (2014), 397-405.

• Journal of Applied Mechanics Award (2018)
• Featured article in Aerospace & Defense Technology (2017)
• Donald Coles Prize, Caltech (2015)
• Charles D. Babcock Award, Caltech (2014)