Rani Elhajjar, Ph.D.

Associate Professor
Civil & Environmental Engineering

Dr. Elhajjar is the director of UWM’s Engineering Mechanics and Composites Research Laboratory. The lab’s main focus includes testing composite structures for safety, developing composite materials for zero greenhouse emissions and developing on-site non-destructive testing methods. Dr. Elhajjar is field leader on carbon fiber and cellulose nanofiber composites.



  • Ph.D., Civil Engineering, Georgia Institute of Technology, 2004
  • M.S., Civil Engineering, University of Texas at Austin, 2000
  • B.S., Civil Engineering, University of Nebraska Lincoln-Omaha, 1998


Research Focus:

  • Effects of defects in composite structures.
  • Sustainable composite materials.
  • Full field non-destructive testing methods.


Honors and Awards:

  • Tau Beta Pi Engineering Honor Society
  • Phi Kappa Phi Honor Society


  • 2013 - co-edited along with Dr. Valeria La Saponara and Dr. Anastasia Muliana, Smart Composites – Mechanics and Design, by CRC Press. The book addresses the current progress in the mechanics and design of smart composites and multifunctional structures.


  • Shams, S. M. and, Elhajjar, R., “Overlay Patch Repair of Scratch Damage in Carbon Fiber/Epoxy Laminated Composites,” Composites A, 2013. 49: 148–156.
  • Shams, S. M. and, Elhajjar, R., “Effects of Scratch Damage on Progressive Failure of Laminated Carbon Fiber/Epoxy Composites,” International Journal of Mechanical Sciences, 2013. 67: 70-77.
  • Qamhia, I., Sabo, R., and Elhajjar, R., “Static and Dynamic Characterization of Cellulose Nanofibril Scaffold-Based Composites,” Bioresources Journal, 2014. 9(1): 381-392.
  • Martinsen, M., Elhajjar, R., and, Berzins, D., “3D Full Field Strain Analysis of Polymerization Shrinkage in a Dental Composite,” Dental Materials, 2013. 29:161-167.
  • Elhajjar, R. F., and Qamhia, I. I., “Modeling and Characterization of the Moisture Dependent Bilinear Behavior of Regenerated Cellulose Composites,” Journal of Wood Science, 2013. 59(4): 331-336.
  • Qamhia, I. I., Lauer-Hunt, E. M, Elhajjar, R., “Identification of Acoustic Emissions from Porosity and Waviness Defects in Continuous Fiber Reinforced Composites,” ASTM Journal of Advances in Civil Engineering Materials, 2013. 2(1): 14 pages.
  • Elhajjar, R., Shams, S. M. and, Kehrl, D. J., “Closed Form Solutions for Predicting the Elastic Behavior of Quasi-Isotropic Triaxially Braided Composites,” Composite Structures, 2013. 101: 1-8.
  • Yang, P. and Elhajjar, R., “Porosity Content Evaluation in Carbon-Fiber / Epoxy Composites using X-ray Computed Tomography,” Polymer-Plastics Technology and Engineering, 2013. Accepted for publication.
  • Haj-Ali, R. and Elhajjar, R., “An Infrared Thermoelastic Stress Analysis Investigation of Single Lap Shear Joints in Continuous and Woven Carbon/Fiber Epoxy Composites,” International Journal of Adhesion and Adhesives, 2013.  Accepted for publication.
  • Song, K., Roehrich, D., and Elhajjar, R., “Full Field Non-Contact Investigation of Deformation Fields in Fillet and Plug Welds,” SAE International Journal of Materials and Manufacturing, 2013.  Accepted for publication.
  • . Haj-Ali, R., Zemer, H., Elhajjar, R., Aboudi, J, “Piezoresistive Fiber-Reinforced Composites: A Coupled Nonlinear Micromechanical- Microelectrical Modeling Approach,” International Journal of Solids and Structures, 2013. Accepted for publication.
  • Petersen, D., Elhajjar, R., and Kabor, B., “On the tension strength of carbon/epoxy composites in the presence of deep scratches,” Engineering Fracture Mechanics, 2012. 90: 30-40.
  • Yang, P. and Elhajjar, R., “Porosity Defect Morphology Effects in Carbon Fiber - Epoxy Composites,” Polymer-Plastics Technology and Engineering, 2012. 51(11): 1141-1148
  • Elhajjar, R., and, Lo Ricco, M., “A Modified Average Stress Criterion For Open-Hole Tension Strength In the Presence of Localized Wrinkling,” Plastics, Rubber and Composites: Macromolecular Engineering. 2012. 41(9): 396-406
  • Sisneros, P. M., Yang, P. and Elhajjar, R., “Fatigue and Impact Behaviour of Carbon Fibre Composite Bicycle Forks,” Fatigue & Fracture of Engineering Materials & Structures, 2012. 35(7): 672-682.
  • Masoodi, R., Elhajjar, R., Pillai, K., and Sabo, R., “Mechanical characterization of a cellulose nanofiber and bio-based epoxy composite,” Materials & Design, 2012. 36:570-576.
  • Mishra, K. and Elhajjar, R., “Nonlinear Strain Invariant Failure Approach for Fiber Reinforced Composite Materials,” International Journal of Materials and Structural Integrity, 2012. 6 (2/3/4): 284-296.
  • Elhajjar, R., and Petersen, D., R.,  “Gaussian Function Characterization of Unnotched Tension Behavior in a Carbon/Epoxy Composite Containing Localized Fiber Waviness,” Composite Structures, 2011. 93:2400–2408.
  • Elhajjar, R., and Petersen, D., “Adhesive Polyvinyl Chloride Coatings for Quantitative Strain Measurement in Composite Materials,” Composites Part B, 2011. 42(7):1929-1936.
  • Haj-Ali, R., Wei, B., Johnson, S. and Elhajjar, R., “Thermoelastic and infrared-thermography methods for surface strains in cracked orthotropic composite materials,” Engineering Fracture Mechanics, vol. 75, pp.  58-75, 2008
  • Elhajjar, R., and Haj-Ali, R.,  "In-plane Shear Testing of Thick-Section Pultruded FRP Composites using a Modified Arcan Fixture,” Composites Part B: Engineering, vol. 35, no. 5, pp. 421-428, 2004
  • Elhajjar, R., and Haj-Ali, R., “A Quantitative Thermoelastic Stress Analysis Method for Pultruded Composites,” Composites Science and Technology, vol. 63, no. 7, pp. 967-978, 2003.
  • Elhajjar, R. and Haj-Ali, R., “Mode-I Fracture Toughness Testing of Thick Section FRP Composites using the ESE(T) Specimen,” Engineering Fracture Mechanics, vol. 72, no. 4, pp. 631-643, 2005
  • . Haj-Ali, R., Elhajjar, R., and Muliana, A., “Cohesive fracture modeling of crack growth in thick-section composites,” Engineering Fracture Mechanics, vol. 73, pp. 2192-2209, 2006
  • Haj-Ali, R. and Elhajjar, R.,"Crack Propagation Analysis of Mode-I Fracture in Pultruded Composites using Micromechanical Constitutive Models," Mechanics of Materials International Journal, vol. 35, no. 9, pp. 885-902, 2003
  • Elhajjar, R., and Haj-Ali, R., "Infrared (IR) Thermography for Strain Analysis in Pultruded Fiber Reinforced Plastics,” Experimental Techniques, vol. 28, no. 2, pp.19-22, 2004.