Page Map

• Current Research
• Education
• Experience
• Awards
• Professional Service
• Journal Publications
• Book Chapters
• Conference Publications
• Collaborators

Current Research

• Coupled Continuum and Atomistic Models of Dislocations

  • Development of numerical methods which coupled continuum and atomistic models of materials.
    
  • These method allows for atomistic resolution of dislocation core behaviour while still modelling most of the domain with a computationally more efficient continuum model.
    
  • For more information see (PDF (23MB))
    
  
  a) Decomposition of the domain into continuum (modeled by XFEM) and atomistic part. b) Displacement of atoms in the x-direction. The discontinuity from the dislocation can be seen. c) Closeup of displacements here the top-most dislocation core.

• Dislocation Modelling with the Extended Finite Element Method

  • Development of numerical methods for continuum based models of dislocations.
  • Focus on prediction of plasticity and failure in thin films and MEMS devices.
  • For more details see (PDF)
    

• Modeling Extreme Loads on Pipelines

  • Development of soil-structure interaction models for simulating the effect of ice scours on pipelines
  • Study of very soil large deformations
  
  Left: Finite element mesh for an ice scour simulation. Right: Soil deformations due to ice scouring. Green material denotes soil initially in the trench.

• Fracture Mechanics using the Extended Finite Element Method (XFEM)

Education

• Doctor of Philosophy in Mechanical Engineering: 2009

  Northwestern University, Department of Mechanical Engineering
  Advisor: Ted Belytschko
  Scholarship: Canada Graduate Scholarship from the Natural Sciences and Engineering Research Council of Canada (NSERC)
  

• Bachelor in Applied Science in Mechanical Engineering: 2002

  University of Ottawa, Department of Mechanical Engineering
  Graduated Summa Cum Laude
  Gold Medal Canadian Society of Mechanical Engineers (CSME)
  Professional Engineers of Ontario (PEO) Scholarship

• Bachelor of Science in Computing Technologies: 2002

  University of Ottawa, Department of Mechanical Engineering and School of Information Technology and Engineering
  Graduated Summa Cum Laude

Experience

Research Engineer: 2002-2004

• Development of explicit Eulerian Finite Element models to analyze the effect of ice scours on buried offshore artic pipelines, and of implicit/explicit models to analyze the effect of the impact of objects on pressurized concrete encased pipelines.
• Developed an object oriented Finite Element framework.
• Supervised the work of several co-op students

Awards

• 2009 1st Place in the 2009 Robert J. Melosh Medal Competition (link)
• 2005-2008 Canada Graduate Scholarship from the Natural Sciences and Engineering Research Council of Canada (NSERC)
• 2005 Best Paper at Offshore Mechanics and Arctic Engineering 2005
• 2004 Walter P. Murphy Scholarship
• 2001 Gold Medal Canadian Society of Mechanical Engineers (CSME)
• 2001 Earl Dudgeon Memorial Scholarship
• 2000 Professional Engineers of Ontario (PEO) Scholarship
• 1999 J.V. Marsh Memorial Award
• 1998 J.L. Richards Award
• 1998-2001 University of Ottawa Merit Scholarship

Professional Service

• 2009-present: Reviewer for Computer Methods in Applied Mechanics and Engineering.
• 2006-present: Reviewer for International Journal for Numerical Methods in Engineering.
• 2008-present: Reviewer for Computational Mechanics.
• 2007-2008 President for the Mechanical Engineering Graduate Student Society (MEGSS)
• 2006-2007 Treasurer for the Mechanical Engineering Graduate Student Society (MEGSS)
• 2005-2006 Faculty Coordinator for the Mechanical Engineering Graduate Student Society (MEGSS)

Journal Publications

1. T. Rabczuk, R. Gracie, J-H. Song, and T. Belytschko, Immersed Particle Method for Fluid-Structure Interaction. International Journal for Numerical Methods in Engineering, (accepted 2009) .

2. M. Xu, R. Gracie and T. Belytschko, A Continuum-to-Atomistic Bridging Domain Method for Composite Lattices. International Journal for Numerical Methods in Engineering, (accepted 2009) .

3. T. Belytschko, R. Gracie, and G. Ventura, A Review of the Extended/Generalized Finite Element Methods for Material Modelling. Modelling and Simulation in Materials Science and Engineering,17:043001, 2009 . (Submitted Version) (doi: 10.1088/0965-0393/17/4/043001)

4. R. Gracie, and T. Belytschko, Concurrently Coupled Atomistic and XFEM Models for Dislocations and Cracks. International Journal for Numerical Methods in Engineering, 78(3): 354 - 378, 2009. (PDF) (doi: 10.1002/nme.2488)

5. J. Oswald, R. Khare, R. Gracie, and T. Belytschko, An Extended Finite Element Method for Dislocations in Complex Geometries: Thin Films and Nanotubes. Computer Methods in Applied Mechanics and Engineering, 198(21):1872-1886, 2009. (preprint PDF) (doi: 10.1016/j.cma.2008.12.025)

6. G. Ventura, R. Gracie, and T. Belytschko, Fast integration and weight function blending in the extended finite element method. International Journal for Numerical Methods in Engineering, 77(1):1-29, 2009. (PDF) (doi: 10.1002/nme.2387)

7. R. Gracie, H.W. Wang, and T. Belytschko, Blending in the eXtended Finite Element Method by Discontinuous Galerkin and Assumed Strain Methods. International Journal for Numerical Methods in Engineering, 74(11): 1645-1669, 2008. (PDF) (doi: 10.1002/nme.2217)

8. R. Gracie, J. Oswald, and T. Belytschko, On a new extended finite element method for dislocations: core enrichments. Journal of Mechanics and Physics of Solids, 56:200-214, 2008. (PDF) (doi: 10.1016/j.jmps.2007.07.010)

9. T. Belytschko and R. Gracie, On XFEM applications to dislocations and interfaces. International Journal of Plasticity. 23(10-11):1721-1738, 2007. (PDF) (doi: 10.1016/j.ijplas.2007.03.003)

10. R. Gracie, G. Ventura, and T. Belytschko. A new fast method for dislocations based on interior discontinuities. International Journal for Numerical Methods in Engineering, 69:423-441, 2007. (PDF) (doi: 10.1002/nme.1896)

11. Konuk, I. and R. Gracie A three-dimensional Eulerian finite-element model for ice scour. Journal of Pipeline Integrity. 3(4):207-220, 2004. (link)

12. R. Gracie, I. Konuk and F. Abdelfettah, An FEM analysis of the impact of external objects on pipelines. Journal Pipeline Integrity 2(4):241-250, 2003. (link)

Book Chapters

1. M. Xu, R. Gracie, and T. Belytschko. Concurrent Coupling of Atomistic and Continuum Models, Multiscale Methods: Bridging the Scales in Science and Engineering. Ed. J. Fish. Oxford Press, (in press) ISBN: 978-0-19-923385-4 (PDF) (link)

2. T. Belytschko, J.H. Song, H.W. Wang and R. Gracie. On applications of XFEM to dynamic fracture and dislocations, IUTAM Symposium on Discretization Methods for Evolving Discontinuities. Proceedings of the IUTAM Symposium: Lyon, France, 2006. Ed. A. Combescure, R. de Borst, T. Belytschko, Vol. 5, 2007, ISBN: 978-1-4020-6529-3 (link)

Conference Publications

1. R. Gracie and T. Belytschko, An Extended Bridging Domain Method for Continuum-Atomistic Simulations of Discontinuities. 8th World Congress on Computational Mechanics, Venice July 2008. (PDF version of my presentation (23MB))

2. R. Gracie and T. Belytschko, 2D dislocations modelled by interior discontinuities in a Discontinuous Galerkin method. 9th US National Congress on Computational Mechanics (USNCCM), San Francisco, July 2007. (PDF)

3. R. Gracie and T. Belytschko, On a new method for modelling dislocations. 21st Canadian Congress of Applied Mechanics, Toronto June 2007. (PDF)

4. R. Gracie and T. Belytschko, An assumed strain blending element formulation for linear elastic fracture mechanics. 7th World Congress on Computational Mechanics, Los Angeles July 2006. (PDF)

5. I. Konuk, S. Yu, and R. Gracie, A 3-dimensional continuum ALE model for ice scour - study of trench effects. Proceedings of the 24th International Conference on Offshore Mechanics and Arctic Engineering, Halkidiki, Greece, June 2005. (PDF) Awarded Best Paper

6. I. Konuk, S. Yu, and R. Gracie, An ALE FEM Model of Ice Scour. Proceeding of the 11th International Conference of the International Association of Computer Methods and Advances in Geomechanics, Turin, Italy, June 19-21, 2005. (PDF)

7. I. Konuk, and R. Gracie, A 3-Dimensional Eulerian FE Model for Ice Scour. International Pipeline Conference, Calgary, Alberta, October 2004, paper IPC04-0075. (link)

Collaborators

• Dr. G. Ventura: Research Assistant Professor, Politecnico di Torino
• Dr. J.-H. Song : Post-Doctoral Fellow at Northwestern University
• Jay Oswald, MS: PhD Student, Northwestern University
• Dr. H. Waisman : Assistant Professor, Columbia University
• Dr. I. Konuk: Senior Geotechnical Engineer, Natural Resources Canada
• Dr T. Menouillard : Post-Doctoral Fellow at Northwestern University
• Hongwu Wang: Former PhD Student and Post-Doc at Northwestern University; currently at Abaqus.