## Brandon Runnels

### Title(s):

Department of Aerospace Engineering

Department of Mechanical Engineering (courtesy)

### Office

2349 Howe Hall

537 Bissell Rd

Ames, IA 50011

### Information

The discipline of solid mechanics is concerned with determining how structural materials respond to external loading, and – often – predicting the reliability and safety of the materials in their environments. Materials are uniquely complex in that they exhibit vastly different behaviors at different scales. At the nanometer scale, they behave as lattices of atoms or, perhaps, chains of polymer. At the mesoscale, they exhibit features, such as grain boundaries, that act as key players in mechanical processes. At the application scale, these microscopic behaviors present as behaviors that we all know and understand: plasticity, viscoelasticity, fracture, etc. Understanding this atoms-to-applications picture is a grand challenge in solid mecahnics.

Our group uses the latest computational methods to develop new tools to enable better simulation of solid mechanics. We are interested in a broad range of applications, ranging from solid rocket propellant to asteroid-satellite impact.

#### Research Website: Solid mechanics research group

## Education

PhD, Mechanical Engineering, California Institute of Technology

MS, Mechanical Engineering, California Institute of Technology

BS, Mechanical Engineering, New Mexico Institute of Mining and Technology

### Publications

See updated publication list.

### Journal Articles

- A fully-coupled mechanics and regression model for deflagration of ‘solid composite propellants with realistic microstructure [pdf] [bibtex]M Meier, B Runnels*
*engrXiv Preprint*(2024) - Facet and energy predictions in grain boundaries: lattice matching and molecular dynamics [pdf] [bibtex]B Dobrovolski, C Braxton Owens, Gus L W Hart, E Homer, B Runnels*
*arXiv Preprint*(2024) - An atomistic survey of shear coupling in asymmetric tilt grain boundaries and interpretation using the disconnections framework [bibtex]H Joshi, I Chesser, B Runnels, N Admal*
*Submitted*(2024) - Grain boundary network plasticity: reduced-order modeling of deformation-driven shear-coupled microstructure evolution [pdf] [bibtex]D Bugas, B Runnels*
*Journal of the Mechanics and Physics of Solids*(2024) - Diffuse interface method for solid composite propellant ignition and regression [pdf] [bibtex]M Meier, EM Schmidt, P Martinez, JM Quinlan, B Runnels*
*Combustion and Flame*(2024) - Robust, strong form mechanics on an adaptive structured grid: efficiently solving variable-geometry near-singular problems with diffuse interfaces [pdf] [bibtex]V Agrawal, B Runnels*
*Computational Mechanics*(2023) - Automated determination of grain boundary energy and potential-dependence using the OpenKIM framework [pdf] [bibtex]B Waters, D Karls, I Nikiforov, R Elliott, E Tadmor, B Runnels*
*Computational Materials Science*(2023) - Self-similar diffuse boundary method for phase boundary driven flow [pdf] [bibtex]EM Schmidt, JM Quinlan, B Runnels*
*Physics of Fluids*(2022)*Invited* - Comparison of evolving interfaces, triple points, and quadruple points for discrete and diffuse interface methods [pdf] [bibtex]E Eren*, B Runnels, J Mason
*Computational Materials Science*(2022) - A diffuse interface method for solid-phase modeling of regression behavior in solid composite propellants [pdf] [bibtex]B Kanagarajan, JM Quinlan, B Runnels*
*Combustion and Flame*(2022) - Interface History on Strain Field Evolution in Epoxy Resins [bibtex]J Strutton, N Moser, EJ Garboczi, A Jennings, B Runnels, JM McCollum*
*ACS Applied Polymer Materials*(2022) - A taxonomy of grain boundary migration mechanisms via displacement texture characterization [pdf] [bibtex]I Chesser*, B Runnels, E Holm
*Acta Materialia*(2022) - Multiphase field modeling of grain boundary migration mediated by emergent disconnections [pdf] [bibtex]M Gokuli, B Runnels*
*Acta Materialia*(2021) - Block structured adaptive mesh refinement and strong form elasticity approach to phase field fracture with applications to delamination, crack branching and crack deflection [pdf] [bibtex]V Agrawal*, B Runnels
*Computer Methods in Applied Mechanics and Engineering*(2021) - Optimal transportation of grain boundaries: A forward model for predicting migration mechanisms [pdf] [bibtex]I Chesser, E Holm, B Runnels*
*Acta Materialia*(2021) - Massively parallel finite difference elasticity using a block-structured adaptive mesh refinement with a geometric multigrid solver [pdf] [bibtex]B Runnels*, V Agrawal, W Zhang, A Almgren
*Journal of Computational Physics*(2021) - Experimental and numerical investigation into mechanical degradation of polymers [bibtex]A Celestine*, V Agrawal, B Runnels
*Composites Part B: Engineering*(2020) - Phase field disconnections: A continuum method for disconnection-mediated grain boundary motion [pdf] [bibtex]B Runnels*, V Agrawal
*Scripta Materialia*(2020) - A continuum thermodynamic framework for grain boundary motion [pdf] [bibtex]I Chesser, T Yu, C Deng, E Holm, B Runnels*
*Journal of the Mechanics and Physics of Solids*(2020) - A new approach for phase field modeling of grain boundaries with strongly nonconvex energy [pdf] [bibtex]JG Ribot, V Agrawal, B Runnels*
*Modelling and Simulation in Materials Science and Engineering*(2019) - Determination of minimal energy facet structures in Sigma3 and Sigma9 grain boundaries: experiment and simulation [pdf] [bibtex]AC Leff, B Runnels*, A Nye, ML Taheri, IJ Beyerlein
*Materialia*(2019) - A projection-based reformulation of the coincident site lattice Sigma for arbitrary bicrystals at finite temperature [pdf][commentary] [bibtex]B Runnels*
*Acta Crystallographica A*(2017)*Cover* - A relaxation method for the energy and morphology of grain boundaries and interfaces [pdf] [bibtex]B Runnels, IJ Beyerlein, S Conti, M Ortiz*
*Journal of the Mechanics and Physics of Solids*(2016) - An analytical model of interfacial energy based on a lattice-matching interatomic energy [pdf] [bibtex]B Runnels, IJ Beyerlein, S Conti, M Ortiz*
*Journal of the Mechanics and Physics of Solids*(2016)

### Conference Papers

- A Diffuse Interface Approach to Modeling Acoustic Wave-Droplet Interactions S Patel, J Griffin, E Schmidt, B Runnels, JM Quinlan
*AIAA SciTech*(2024) - A Diffuse Interface Model for Viscous Compressible Flow through Eroding Porous Media E Schmidt, M Meier, JM Quinlan, B Runnels
*AIAA SciTech*(2024) - Computational determination of particle size and geometry effects in solid composite propellants using the phase field method M Meier, JM Quinlan, B Runnels
*AIAA SciTech*(2024) - Modeling Optimization of Stencil Computations Via Domain-level Properties B Nesterenko, Q Yi, PH Lin, C Liao, D. Quinlan, B Runnels
*PMAM 2022*(2022) - Phase field modeling of solid phase AP/HTPB to determine the effect of particle distribution on regression rate B Kanagarajan, JM Quinlan, B Runnels
*AIAA SciTech*(2022) - A Diffuse Interface Method for the Coupling of Solid and Gaseous Phases in a 1D Verification Problem for Combustion of AP/HTPB E Schmidt, J.M Quinlan, Brian Bojko, B Runnels
*AIAA SciTech*(2022) - Design, development, and assembly of sub-orbital space flight structural health monitoring experiment W Reiser, B Runnels, C White, A Light-Marquez, A Zagrai, D Siler, S Marinsek, A Murray, S Taylor, G Park, C Farrar, R Sansom
*SPIE Conference Proceedings*(2012)

### Presentations

- Grain boundary plasticity: defects to continuum modeling Invited Talk – Keynote,Internaional Conference on Plasticity, Damage, and Fracture, Panama City, Panama, 1/6/2024
- Modeling Solid Rocket Motors: condensed phase mechanics simulations at the mesoscale Seminar,University of Iowa Mechanical Engineering Seminar, Iowa City, IA, 10/12/2023
- Grain boundary network plasticity: Multiscale modeling of deformation-driven microstructure evolution Contributed Talk,SES 2023, Minneapolis, MN, 10/10/2023
- Predicting damage initiation with computer vision Invited Talk,SES 2023, Minneapolis, MN, 10/9/2023
- The mechanics of grain boundaries and microstructure evolution: Exploring the phenomenon of grain boundary migration, from atoms to twins Seminar,Iowa State MSE Seminar, Ames, IA, 10/2/2023
- Modeling solid rocket motors: condensed phase mechanics simulations at the mesoscale Seminar,New Mexico Tech Seminar, Socorro, NM, 4/25/2023
- Predicting damage initiation with computer vision Invited Talk,MRS 2023, San Francisco, CA, 4/11/2023
- Simulating solid rocket propellants at the mesoscale Seminar,CCSE Seminar, Berkeley, CA, 4/10/2023
- Modeling the burn behavior of solid composite propellants for rocket propulsion Seminar,BYU Mechanical Engineering Seminar, Provo, UT, 4/2/2023
- The mechanics of grain boundaries and microstructure evolution Seminar,EPFL Seminar, Lausanne, Switzerland, 3/21/2023
- Simulating solid rocket propellants at the mesoscale Seminar,IMES Seminar, ETH Zürich, Zürich, Switzerland, 3/10/2023
- The mechanics of grain boundaries and microstructure evolution Seminar,TU Dresden Seminar, Dresden, Germany, 3/2/2023
- The mechanics of grain boundaries and microstructure evolution Seminar,Mechanics and Materials Seminar, ETH Zürich, 2/23/2023
- A Self-Similar Diffuse Interface Method for a Rotating Ablating Cylinder Contributed Talk,APS Fluids, Indianapolis, IN, 11/22/2022
- Network Plasticity:A Mesoscale-to-Continuum Model for Grain Boundary Mediated Plasticity Invited Talk,SES 2022, College Station, TX, 10/18/2022
- Shear Coupled Microstructure Evolution with Phase Field Emergent Disconnections Contributed Talk,MMM 2022, Baltimore, MD, 10/4/2022
- Phase Field Emergent Disconnections in Grain Boundary Migration Contributed Talk,USNC/TAM 2022, Austin, TX, 6/24/2022
- Network Plasticity: a Mesoscale-to-Continuum Model for Grain Boundary Mediated Plasticity Contributed Talk,USNC/TAM 2022, Austin, TX, 6/23/2022
- Phase Field Modeling of Regression Rates and Morphology in Solid Composite Propellants Contributed Talk,USNC/TAM 2022, Austin, TX, 6/22/2022
- Emergent Disconnections in Phase Field Microstructure: Modeling Complex Boundary Migration at the Mesoscale Contributed Talk,TMS 2022, Anaheim, CA, 2/28/2022
- Simulating solid rocket motor composite propellants at the mesoscale Seminar,UCCS Physics Seminar, Colorado Springs, CO, 2/25/2022
- Simulating solid rocket motor composite propellants at the mesoscale Seminar,Auburn Aerospace Engineering Seminar, Virtual, 9/10/2021
- Phase field emergent disconnections: Exploring complex grain boundary migration from the mesoscale perspective Contributed Talk,USNCCM 2021, Virtual, 7/26/2021
- Microstructure evolution in polycrystalline metals: from optimal transportation to phase field disconnections Seminar,Indian Institute of Science Seminar, Bangalore, India, 3/31/2021
- Quantifying potential dependence of grain boundary properties using OpenKIM Invited Talk,Society of Engineering Science Annual Technical Meeting, Virtual, 9/30/2020
- Unifying mechanisms of grain boundary migration through a continuum thermodynamic framework: Applying insights from crystal plasticity to microstructure evolution Seminar,Auburn University Aerospace Engineering Seminar, Auburn, AL, 1/24/2020
- Unifying mechanisms of grain boundary migration through a continuum thermodynamic framework: Applying insights from crystal plasticity to microstructure evolution Seminar,CU Boulder Aerospace Engineering Seminar, Boulder, CO, 11/1/2019
- Unifying mechanisms of grain boundary migration through a continuum thermodynamic framework: Applying insights from crystal plasticity to microstructure evolution Seminar,UC Santa Barbara Mechanical Engineering Seminar, Santa Barbara, CA, 10/21/2019
- Unifying mechanisms of grain boundary migration through a continuum thermodynamic framework Invited Talk,USACM Thematic Workshop on Recent Advances in the Modeling and Simulation of the Mechanics of Nanoscale Materials, Philadelphia, PA, 8/22/2019
- Mesoscale Modeling and Simulation of Microstructure Evolution Driven by Strong Anisotropic Grain Boundary Energy and Mobility Contributed Talk,USNCCM 2019, Austin, TX, 7/30/2019
- Atomistic to Continuum Modeling of Metalized Polyvinylidene Fluoride with Aluminum Nanoparticles Contributed Talk,TMS 2019, San Antonio, TX, 3/12/2019
- The effect of strong anisotropic grain boundary energy on microstructure formation and evolution: mesoscale modeling and simulation Contributed Talk,TMS 2019, San Antonio, TX, 3/12/2019
- Solid mechanics applications with AMReX: Simulating microstructure evolution in metals, solid burn in energetics, and degradation in polymers Invited Talk,SIAM CSE, Spokane, WA, 2/25/2019
- The effect of strong anisotropic grain boundary energy and mobility on microstructure formation and evolution: mesoscale modeling and simulation Seminar,Colorado State University Mechanical Engineering Seminar, Ft Collins, CO, 2/19/2019
- The effect of strong anisotropic grain boundary energy and mobility on microstructure formation and evolution: mesoscale modeling and simulation Seminar,UC Davis Materials Science Seminar, Davis, CA, 1/15/2019
- The effect of strong anisotropic grain boundary energy and mobility on microstructure formation and evolution: mesoscale modeling and simulation Invited Talk,MMM 2018, Osaka, Japan, 11/1/2018
- Phase field modeling of microstructure evolution with anisotropy and orientation dependence, informed by a realistic model for boundary energy Seminar,AFRL Wright Patterson Seminar, Dayton, OH, 7/9/2018
- Computational modeling of VDF composites Invited Talk,Fluoropolymer 2018, Denver, CO, 6/26/2018
- Phase field modeling of grain boundary migration with anisotropy and orientation dependence, informed by a realistic model for boundary energy Contributed Talk,USNC/TAM, Chicago, IL, 6/8/2018
- Phase Field Simulation of Microstructure Evolution Driven by Strong Grain Boundary Anisotropy Computed Using Realistic Models for Grain Boundary Energy Contributed Talk,TMS 2018, Phoenix, AZ, 3/12/2018
- How grain boundaries drive material behavior: from analytic modeling to microstructure evolution Seminar,Auburn University Aerospace Engineering Seminar, Auburn, AL, 10/23/2017
- How grain boundaries drive material behavior: from analytic modeling to microstructure evolution Seminar,Missouri S&T Mechanical Engineering Seminar, Rolla, MO, 10/19/2017
- Phase field simulation of microstructure evolution driven by grain boundary anisotropy – Kinetics of microfaceting with realistic boundary energy Contributed Talk,SES 2017, Boston, MA, 7/27/2017
- Lattice matching for predicting anisotropic grain boundary properties…towards grain boundary engineering for designed microstructure Contributed Talk,TMS 2017, San Diego, CA, 2/27/2017
- Modeling and simulation of grain boundary anisotropy-driven mechanics in fcc and bcc materials Contributed Talk,SES 2016, College Park, MA, 10/4/2016
- Modeling grain boundaries in metals with optimal transportation theory, calculus of variations, and the phase field method Seminar,Colorado State University Mathematics Seminar, Ft Collins, CO, 9/15/2016
- Modeling anisotropic grain boundary energy and morphology in cubic crystals with applications to microstructural evolution Contributed Talk,EMI/PMC 2016, Nashville, TN, 5/24/2016
- A general and predictive model of anisotropic grain boundary energy and morphology Contributed Talk,TMS 2016, Nashville, TN, 2/16/2016
- A general and predictive model of anisotropic grain boundary energy and morphology for polycrystal-level simulations Seminar,Vanderbilt Mechanical Engineering Seminar, Nashville, TN, 2/15/2016
- Modeling grain boundary energy anisotropy with applications to morphology and computational microstructural evolution Seminar,University of Minnesota Solid Mechanics Seminar, Minneapolis, MN, 12/1/2015
- A new model for the energy and morphology of grain boundaries and interfaces Contributed talk,IMECE 2015, Houston, TX, 11/15/2015
- Modeling grain boundary energy anisotropy with applications to morphology and computational microstructural evolution Seminar,Colorado School of Mines Mechanical Engineering Seminar, Golden, CO, 11/1/2015
- A new model for anisotropic grain boundaries: a geometric and variational approach for predicting energy and morphology Contributed Talk,SES 2015, College Station, TX, 10/1/2015
- Temperature-dependent modeling of grain boundary energy anisotropy and applications to interface morphology Invited Talk,American Physical Society – Four Corners Annual Meeting, Phoenix, AZ, 10/1/2015
- A fast, general, predictive model for grain boundary energy anisotropy with applications to morphology and computational microstructural evolution Seminar,CU Boulder Mechanical Engineering Seminar, Boulder, CO, 10/1/2015
- A variational approach to interfaces: a new method for predicting energy and morphology of grain boundaries Contributed talk,USNCCM 2015, San Diego, CA, 7/1/2015
- A variational approach to crystalline interfaces: a new method for predicting interface energy and morphology Seminar,CU Boulder Mechanical Engineering Seminar, Boulder, CO, 10/1/2014
- A relaxation method for predictively determining interface morphology Contributed talk,SES 2014, Lafeyette, IN, 10/1/2014
- A general geometric model for interface energy Contributed talk,United States National Congress on Theoretical and Applied Mechanics, East Lansing, MI, 6/1/2014
- An analytical model for predicting energy and morphology of arbitrary crystal interfaces Seminar,New Mexico Tech Mechanical Engineering Seminar, Socorro, NM, 9/24/2013
- Modeling of thermally-activated dislocation cross-slip Contributed talk,Los Alamos National Laboratory Student Seminar, Los Alamos, NM, 8/8/2012

### Primary Strategic Research Area

Advanced Materials & Manufacturing