I am a mechanical engineer currently working as a postdoctoral researcher in the Computational Geosciences Group within Physical and Life Sciences.

My research aims to use reactive continuum theories to develop models for complex materials that can evolve in response to mechanical, chemical, thermal, and electrical loading, and implementing these models into finite element software. Prior to joining Lawrence Livermore, these efforts were focused on active biomaterials, including articular cartilage, the lamina cribrosa of the eye, and DNA-crosslinked growing hydrogels for smart robotics.

At LLNL, my work focuses on characterizing the shock response of structured heterogeneous materials and understanding the limits of continuum models in capturing this complex behavior. Most of this work is applied to additively manufactured materials and performed in conjunction with experimental shock testing on the NIF.

I am also a developer for the open-source finite element software FEBio (febio.org), a multiphysics code originally developed for the biophysics and biomechanics communities. My work on that effort is mostly focused on frictional contact algorithms for hydrated-pressurized porous media and modeling inelastic material behavior within the framework of reactive constrained mixture theory.

Postdoctoral Fellow, School of Medicine, Johns Hopkins University, 2020-2022

PhD, Mechanical Engineering, Columbia University, 2020

MPhil, Mechanical Engineering, Columbia University, 2018

MS, Mechanical Engineering, Columbia University, 2016

BME, Mechanical Engineering, University of Delaware, 2014

Google Scholar: https://scholar.google.com/citations?user=5uxxpk8AAAAJ&hl=en&oi=ao

Selected Publications:

1. Ateshian GA and Zimmerman BK. (2023) Modeling inelastic responses using constrained reactive mixtures. European Journal of Solid Mechanics / A, 100:105009.
2. Ateshian GA, Kroupa KR, Petersen CA, Zimmerman BK, Maas SA, and Weiss JA. (2023) Damage mechanics of biological tissues in relation to viscoelasticity. Journal of Biomechanical Engineering, 145(4):041011.
3. Zimmerman BK, Maas SA, Weiss JA, and Ateshian GA. (2022) A finite element algorithm for large deformation biphasic frictional contact between porous-permeable hydrated soft tissues. Journal of Biomechanical Engineering, 144(2):021008.
4. Ateshian GA and Zimmerman BK. (2022) Continuum thermodynamics of constrained reactive mixtures. Journal of Biomechanical Engineering, 144(4):041011.
5. Mei Y, Liu J, Guo X, Zimmerman BK, Nguyen TD, and Avril S. (2021) General finite-element framework of the virtual fields method in nonlinear elasticity. Journal of Elasticity, 145:265-294.
6. Zimmerman BK, Jiang D, Timmins LH, and Ateshian GA. (2021) On the use of constrained reactive mixtures of solids to model finite deformation isothermal elastoplasticity and elastoplastic damage mechanics. Journal of the Mechanics and Physics of Solids, 155:104534.
7. Zimmerman BK, Nims RJ, Chen A, Hung CT, and Ateshian GA. (2021) Direct osmotic pressure measurements in articular cartilage demonstrate non-ideal and concentration-dependent phenomena. Journal of Biomechanical Engineering, 143(4):041007.
8. Zimmerman BK and Ateshian GA. (2018) A surface-to-surface finite element algorithm for large deformation frictional contact in FEBio. Journal of Biomechanical Engineering, 140(8):081013. Editor’s Choice Paper (1 of 12 for 2018).
9. Zimmerman BK, Bonnevie ED, Park M, Zhou Y, Wang L, Burris DL, and Lu XL. (2015) Role of interstitial fluid pressurization in TMJ lubrication. Journal of Dental Research, 94(1):85-92.
10. *Ruggiero L, *Zimmerman BK, Park M, Han L, Wang L, Burris DL, and Lu XL. (2015) Roles of the fibrous superficial zone in the mechanical behavior of TMJ condylar cartilage. Annals of Biomedical Engineering, 43(11):2652-2662.

• (2020) Finalist, NSF PhD Student Paper Competition, ASME International Mechanical Engineering Congress & Exposition
• (2018) Editor’s Choice Paper, Journal of Biomechanical Engineering. For “A surface-to-surface finite element algorithm for large deformation frictional contact in FEBio”
• (2017) 1^st Place, PhD Student Paper Competition, ASME Summer Bioengineering, Biotransport, and Biomechanics Conference
• (2015) National Science Foundation Graduate Research Fellowship
• (2014) Presidential Distinguished Fellowship, Columbia University