Florin Bobaru

Contact Information:
W355 NH
City Campus (Lincoln)
(402) 472-8348
fbobaru2@unl.edu
Email   

Professor
Hergenrader Distinguished Scholar
Academic Degrees
  • Ph.D., Theoretical and Applied Mechanics, Cornell University, Ithaca, NY, 2001
  • M.S., Mathematics and Mechanics of Solids, University of Bucharest, Romania, 1997
  • B.S., Mathematics and Mechanics, University of Bucharest, Romania, 1995
News

  1. New paper accepted in Corrosion Science! See some amazing simulations of pits and lacy covers merging in 3D!!! https://doi.org/10.1016/j.corsci.2019.01.006
  2. New paper on failure in electronic packaging, see https://doi.org/10.1109/TCPMT.2018.2862898
  3. New results on advection-diffusion problems published in Int. J. of Heat and Mass Transfer!
  4. New results on intergranular corrosion damage published in JES!
  5. Our work on pitting corrosion has been highlighted on the May 3rd post on the Facebook page of CORROSION journal ! Check out the simulation movies in the Media tab or the Supplement tab
  6. Prof. Bobaru will give a Keynote presentation on "Crack-path instabilities in glass as a way of determining the peridynamic horizon size in thermally-driven fracture"
    at the 10th European Solid Mechanics Conference in Bologna, Italy, July 2nd-6th, 2018. 
  7. A strange connection between vortices and thermally-driven cracks in glass! Take a look at the fascinating simulation movies in Supplementary material. See the new paper here.
  8. New paper published on corrosion and peridynamic fracture in Materials Science and Engineering A.
  9. New paper on impact and supershear damage front propagation in ceramics published in Int. J. Impact Engineeringhttps://doi.org/10.1016/j.ijimpeng.2017.11.010 
  10. New paper on peridynamic surface corrections published in Computational Mechanics! See it at: http://rdcu.be/vpx
  11. New paper on objectivity of state-based PD models published in Journal of Elasticity. See it at: https://link.springer.com/article/10.1007/s10659-017-9641-6
  12. Congratulations to Guanfeng Zhang for receiving the 2017 UNL College of Engineering Outstanding Graduate Research Assistant Award!  
  13. Handbook of Peridynamic Modeling  just published ! You can purchase it HERE or HERE.   
  14. New papers published in CMAME on selecting the peridynamic kernel, and in JES on the properties of the corrosion diffusion layer in MG alloys! 
  15. Our paper in Engineering Fracture Mechanics (EFM) is Top 3 most cited paper in EFM among papers published since 2011!
  16. Prof. Bobaru awarded the 2016 College of Engineering Faculty Research and Creative Activity Award. http://engineering.unl.edu/awards/faculty-staff-awards/
  17. New paper on fatigue damage and fracture published in Engineering Fracture Mechanics: "Validation of a peridynamic model for fatigue cracking", 162: 76–94 (2016), see http://dx.doi.org/10.1016/j.engfracmech.2016.05.008
  18. New paper on Why Do Cracks Branch? published in International Journal of Fracture anniversary issue. See it at  http://link.springer.com/article/10.1007/s10704-015-0056-8 and check out the 22 simulation movies in the Supplementary Material section.
  19. New paper in Journal of The Electrochemical Society on influence of passive film on corrosion damage. JES, vol. 163 no. 2 C19-C24 (2016). See it at   http://dx.doi.org/10.1149/2.0521602jes

Areas of Research and Professional Interest
  • Damage and fracture with peridynamics
  • Modeling of corrosion damage and stress corrosion cracking
  • Damage in heterogeneous materials (fiber-reinforced composites, polycrystalline ceramics, etc.)
  • Dynamics of Granular Materials
  • Optimization of material composition and optimal shape design
About Florin Bobaru

Ever wondered why does glass break in such complex patterns, fragments and chips? Or how does corrosion of a few bolts and plates bring an entire bridge down? Our research group works on computational models that answer such questions and  explain the behavior observed experimentally in some of the most challenging problems that have puzzled researchers for decades. We use these models for solving problems that deal with heat and mass diffusion, dynamic fracture, and fragmentation. Recent focus is on: peridynamics for impact fracture in glass, glassy-polymers, polycrystalline ceramics, and fiber-reinforced composites; fracture in concrete induced by corrosion; corrosion damage and Stress Corrosion Cracking; dynamics of granular materials and their interaction with elastic media, multidisciplinary optimization, inverse problems, and multiscale and multiphysics methods.

Damage, corrosion, and fracture with peridynamics
The peridynamic theory is a novel reformulation of the classical continuum mechanics which allows one to model fracture, damage, fragmentation in a natural way. In peridynamics, cracks are part of the solution, not part of the problem. We have used such models to explain the role Van der Waals forces play in the deformation and damage behavior of nanofiber networks, to explain the growth of cracks and fragmentation evolution in glass plates, to model trans- and intergranular fracture in polycrystalline ceramics, to discover strain-rate effects in the failure of fiber-reinforced composites, and to simulate the growth of subsurface damage in corrosion. This research is being funded by AFOSR through a MURI project, by ONR, by NAVAIR, by ARO and ARL. Recent past funding includes grants from Boeing Co, Sandia National Laboratories, Callahan Innovation (New Zealand), NASA.  

Dynamics of Granular Materials interacting with vibrating plates
Granular materials are one of the most puzzling material systems. The models we proposed,  simulate the dynamic interaction between a layer of granular material and an elastic vibrating plate to provide us with a deeper understanding of the fascinating dynamic behavior of granular materials. Think of a land- or rock-slide and imagine the possibility of predicting their behavior under their interaction with the elastic soil support.

Optimization of material composition
Is it possible to find the "best" composition of a multi-component material (such as a composite or a functionally graded material - FGM) that maximizes its strength or stiffness, and reduces its mass? Our results on optimal material design of FGMs show new possible architectures that minimize the chance of failure due to thermal and mechanical stresses.

Optimal shape design
What is the best shape of a cooling thermal fin? Our novel algorithms compute optimal shape of systems when there are large shape changes between the initial guess and the final optimal design. Our meshfree approach leads to interesting solutions that mimic naturally occurring systems like the plates on the back of a stegosaurus dinosaur, or the extended surfaces on the inner side of the intestine (intestinal villi). 



Experience

Employee History:

  • University of Nebraska-Lincoln, Hergenrader Distinguished Scholar, August 2017-June 2022. 
  • University of Nebraska-Lincoln, Professor, Mechanical & Materials Engineering, 2013 – present
  • Visiting Scholar, University of Padova, Italy, September 2015.
  • Visiting Associate Professor, Mechanical and Civil Engineering, California Institute of Technology, Pasadena, California, USA, April-August 2011
  • Visiting Scholar, Multiscale Dynamic Material Modeling Department, Sandia National Laboratories, Albuquerque, New Mexico, USA, January-March 2009
  • Visiting Scholar, Fracture Group, Cavendish Lab, University of Cambridge, Cambridge, U.K., September-December 2008
  • University of Nebraska-Lincoln, Associate Professor, Department of Engineering Mechanics, 2007 – 2013
  • University of Nebraska-Lincoln, Assistant Professor, Department of Engineering Mechanics, 2001 – 2007
  • Sandia National Laboratories, Computer Science Research Institute, Albuquerque, NM. Summer Research Fellow. 2002 – 2004, 2005
  • Cornell University, Ithaca, NY. Graduate Teaching and Research Assistant. 1996-2000

Funding
  • AFOSR MURI Center for Material Failure Prediction through Peridynamics (2014-2019)
  • ONR  on corrosion (2015-2017)
  • ONR on fatigue failure in composites (2016-2018)
  • NAVAIR (2014-2015)
  • ARO/ARL (2010-2016)
  • Boeing Co.
  • NASA

Selected Publications

Books

Handbook of Peridynamic Modeling, Edited by  Florin Bobaru, J.T. Foster, P.H. Geubelle, S.A. Silling. Chapman and Hall/CRC, 2017.

Book Chapters:

  1. "Peridynamic Functionally Graded and Porous Materials: Modeling Fracture and Damage",
    Z. Chen, S. Niazi, G. Zhang, and F. Bobaru. In "Handbook of Nonlocal Continuum Mechanics for Materials and Structures", G.Z. Voyiadjis (ed.), 2018. https://doi.org/10.1007/978-3-319-22977-5_36-1

Journal Publications:

h-index = 28, i10-index=39, over 3,100 citations (Google Scholar, Feb. 2019)

  1. S. Jafarzadeh, Z. Chen, J. Zhao, F. Bobaru, "Pitting, lacy covers, and pit merger in stainless steel: 3D peridynamic models", Corrosion Science, 150:17-31 (2019). https://doi.org/10.1016/j.corsci.2019.01.006 
  2. J. Mehrmashhadi, Y. Tang, X. Zhao,  Z. Xu, J. Pan, Q.V. Le, F. Bobaru, "The Effect of Solder Joint Microstructure on the Drop Test Failure: a Peridynamic Analysis", IEEE Transactions on Components, Packaging and Manufacturing Technology9(1)58 - 71 (2019). https://doi.org/10.1109/TCPMT.2018.2862898

  3. J. Zhao, Z. Chen, J. Mehrmashhadi, F. Bobaru, “Construction of a peridynamic model for transient advection-diffusion problems”, International Journal of Heat and Mass Transfer, 126, Part B: 1253-1266 (2018). https://doi.org/10.1016/j.ijheatmasstransfer.2018.06.075
  4. S. Jafarzadeh, Z. Chen, F. Bobaru, “Peridynamic Modeling of Intergranular Corrosion Damage”, Journal of The Electrochemical Society, 165(7): C362-C374 (2018). https://doi.org/10.1149/2.0821807jes

  5. Z. Xu, G. Zhang, Z. Chen, F. Bobaru, "Elastic vortices and thermally-driven cracks in brittle materials with peridynamics", International Journal of Fracture, 209(1-2): 203–222 (2018). https://doi.org/10.1007/s10704-017-0256-5
  6. G. Zhang, G. A. Gazonas, F. Bobaru, "Supershear damage propagation and sub-Rayleigh crack growth from edge-on impact: A peridynamic analysis", International Journal of Impact Engineering, 113: 73-87 (2018). https://doi.org/10.1016/j.ijimpeng.2017.11.010
  7. S. Li, Z. Chen, L. Tan, F. Bobaru, "Corrosion-induced embrittlement in ZK60A Mg alloy", Materials Science and Engineering A, 713: 7-17 (2018). https://doi.org/10.1016/j.msea.2017.12.053
  8. S. Jafarzadeh, Z. Chen, F. Bobaru, “Peridynamic modeling of repassivation in pitting corrosion of stainless steel”, Corrosion, 74(4): 393-414 (2018). http://corrosionjournal.org/doi/abs/10.5006/2615
  9. Quang Van Le, Florin Bobaru, "Surface corrections for peridynamics models in elasticity and fracture", Computational Mechanics, 61(4): 499-518 (2018). http://rdcu.be/vpxv
  10. Quang Van Le, Florin Bobaru, "Objectivity of State-Based Peridynamic Models for Elasticity", Journal of Elasticity131(1): 1-17 (2018). https://doi.org/10.1007/s10659-017-9641-6
  11. G. Zhang, F. Bobaru, "Modeling the evolution of fatigue failure with peridynamics", Romanian  Journal of Technical Sciences - Applied Mechanics, 61(1): 22-40 (2016).
  12. Ziguang Chen, Drew Bakenhus, Florin Bobaru, "A constructive peridynamic kernel for elasticity", Computer Methods in Applied Mechanics and Engineering, 311: 356-373 (2016). doi: 10.1016/j.cma.2016.08.012
  13. Shumin Li, Ziguang Chen, Fei Wang, Bai Cui, Li Tan, Florin Bobaru, "Analysis of Corrosion-Induced Diffusion Layer in ZK60A Magnesium Alloy", Journal of The Electrochemical Society, 163(13): C784-C790 (2016).  doi: 10.1149/2.1001613jes
  14. Guanfeng Zhang, Quang Le, Adrian Loghin, Arun Subramaniyan, Florin Bobaru, "Validation of a peridynamic model for fatigue cracking", Engineering Fracture Mechanics162: 76–94 (2016). doi:10.1016/j.engfracmech.2016.05.008.

  15. G. Sarego,  Q.V. Le, F. Bobaru, M. Zaccariotto, U. Galvanetto, "Linearized state-based peridynamics for 2-D problems", International Journal for Numerical Methods in Engineering,  108(10): 1174-1197 (2016). doi: 10.1002/nme.5250.

  16. Z. Chen, G. Zhang, F. Bobaru, "The Influence of Passive Film Damage on Pitting Corrosion", Journal of The Electrochemical Society163(2),C19-C24, (2016). http://dx.doi.org/10.1149/2.0521602jes

  17. F. Bobaru, G. Zhang, "Why do cracks branch? A peridynamic investigation of dynamic brittle fracture", Special Invited Article Celebrating IJF At 50, International Journal of Fracture196(1): 59-98 (2015). http://dx.doi.org/10.1007/s10704-015-0056-8
  18. Z. Chen, F. Bobaru, "Selecting the kernel in a peridynamic formulation: A study for transient heat diffusion", Computer Physics Communications, 197: 51–60 (2015). http://dx.doi.org/10.1016/j.cpc.2015.08.006

  19. Z. Cheng, G. Zhang, Y. Wang, F. Bobaru, "A peridynamic model for dynamic fracture in functionally graded materials", Composite Structures, 133: 529–546 (2015).   http://dx.doi.org/10.1016/j.compstruct.2015.07.047 
  20. Z. Chen, F. Bobaru, "Peridynamics modeling of pitting corrosion damage", Journal of the Mechanics and Physics of Solids, 78352–381 (2015).  http://dx.doi.org/10.1016/j.jmps.2015.02.015
  21. W. Hu, Y. Wang, J. Yu, C.F. Yen, F. Bobaru, “Impact damage on a thin glass with a thin polycarbonate backing”, International Journal of Impact Engineering62: 152- 165 (2013).
  22. F. Bobaru, YD. Ha, and W. Hu, “Damage progression from impact in layered glass modeled with peridynamics”, Open Engineering, 2(4): 551-561 (2012).
  23. F. Bobaru and W. Hu, “The meaning, selection, and use of the Peridynamic horizon and its relation to crack branching in brittle materials” International Journal of Fracture176: 215–222 (2012).
  24. W. Hu, YD. Ha, F. Bobaru, and S.A. Silling, “The formulation and computation of the nonlocal J-integral in bond-based Peridynamics”, International Journal of Fracture176: 195–206 (2012).
  25. W. Hu, YD. Ha, and F. Bobaru, “Peridynamic model for dynamic fracture in unidirectional fiber-reinforced composites”, Computer Methods in Applied Mechanics and Engineering217–220: 247–261 (2012).
  26. F. Bobaru and M. Duangpanya, “A Peridynamic Formulation for Transient Heat Conduction in Bodies with Evolving Discontinuities”, Journal of Computational Physics231(7): 2764-2785 (2012).
  27. YD. Ha and F. Bobaru, “Characteristics of dynamic brittle fracture captured with peridynamics”,Engineering Fracture Mechanics78: 1156–1168 (2011). doi:10.1016/j.engfracmech.2010.11.020.
  28. F. Bobaru and YD. Ha, “Adaptive refinement and multiscale modeling in 2D Peridynamics”,International Journal for Multiscale Computational Engineering, 9(6): 635-659 (2011).
  29. F. Bobaru, “Peridynamics and Multiscale Modeling” Editorial in Special Issue on “Advances in Peridynamics”, International Journal for Multiscale Computational Engineering9(6): vii-ix (2011).
  30. W. Hu, YD. Ha, and F. Bobaru. “Modeling Dynamic Fracture and Damage in Fiber-Reinforced Composites with Peridynamics”, International Journal for Multiscale Computational Engineering9(6): 707–726 (2011).
  31. A.L. Collins, J.W. Addiss, S.M. Walley, K. Promratana, F. Bobaru, W.G. Proud, D.M. Williamson, “The effect of rod nose shape on the internal flow fields during the ballistic penetration of sand”,International Journal of Impact Engineering, 38(12): 951-963 (2011).
  32. F. Bobaru and M. Duangpanya, “The peridynamic formulation for transient heat conduction,”International Journal of Heat and Mass Transfer53(19-20): 4047-4059 (2010).
  33. YD. Ha and F. Bobaru, “Studies of dynamic crack propagation and crack branching with peridynamics,” International Journal of Fracture162(1-2): 229-244 (2010).
  34. S. A. Silling, O. Weckner, E. Askari, and F. Bobaru, “Crack nucleation in a peridynamic solid,”International Journal of Fracture162(1-2): 219-227 (2010).
  35. F. Bobaru, M. Yang, L.F. Alves, S.A. Silling, E. Askari, and J. Xu, “Convergence, adaptive refinement, and scaling in 1D peridynamics”, International Journal for Numerical Methods in Engineering77: 852-877 (2009).
  36. Principal Guest Editor: Florin Bobaru, J.S. Chen, Joseph A. Turner, "Advances in the Dynamics of Granular Materials", Mechanics of Materials41(6): 635-636, June 2009.
  37. Kitti Rattanadit, Florin Bobaru, Konlayut Promratana, Joseph A. Turner, "Force chains and resonant behavior in bending of a granular layer on an elastic support", Mechanics of Materials,41(6): 691-706, June 2009.
  38. P. Qiao, M. Yang, and F. Bobaru, “Impact mechanics and high-energy absorbing materials: review”, Journal of Aerospace Engineering21(4): 235-248 (2008).
  39. F. Bobaru, “Influence of van der Waals forces on increasing the strength and toughness in dynamic fracture of nanofiber networks: a peridynamic approach”, Modelling and Simulation in Materials Science and Engineering 15: 397-417 (2007).
  40. F. Bobaru, “Designing optimal volume fractions for functionally graded materials with temperature-dependent material properties”, Journal of Applied Mechanics74: 861-874 (2007).
  41. W. Kang, J.A. Turner, F. Bobaru, L. Yang, and K. Rattanadit, “Granular layers on vibrating plates: Effective bending stiffness and particle-size effects”, Journal of the Acoustical Society of America121: 888-896 (2007).
  42. F. Bobaru and S. Rachakonda, “E(FG)2: a new fixed-grid shape optimization method based on the element-free Galerkin meshfree analysis”, Structural and Multidisciplinary Optimization, 32(3): 215-228 (2006).
  43. R.K. Lakkaraju, F. Bobaru, and S.L. Rohde, “Optimization of multilayer wear-resistant 3 thin films using finite element analysis on stiff and compliant substrates”, Journal of Vacuum Science and Technology (A),  24 (1): 146-155 (2006).
  44. S.A. Silling and F. Bobaru, “Peridynamic modeling of membranes and fibers”, International Journal of Non-Linear Mechanics40(2-3): 395-409 (2005).
  45. F. Bobaru and S. Rachakonda, “Optimal shape profiles for cooling fins of high and low conductivity”, International Journal of Heat and Mass Transfer47(23): 4953-4966 (2004).
  46. F. Bobaru and S. Rachakonda, “Boundary layer in shape optimization of convective fins using a meshfree approach”, International Journal for Numerical Methods in Engineering, 60(7): 1215-1236 (2004).
  47. F. Bobaru and Subrata Mukherjee, “Meshless approach to shape optimization of linear thermoelastic solids”, International Journal for Numerical Methods in Engineering53(4): 765-796 (2002).
  48. F. Bobaru and S. Mukherjee, “Shape Sensitivity Analysis and Shape Optimization in Planar Elasticity Using the Element-Free Galerkin Method”, Computer Methods in Applied Mechanics and Engineering190(32-33) 4319-4337 (2001).
  49. F. Bobaru, “Prestressed Elastic Solid Containing a Crack, Subjected to Normal or Tangential Loadings”, Revue Roumaine des Science Technique, Serie de Mecanique Applique41(5-6): 421-429 (1996).

OI: 10.1109/TCPMT.2018.2862898