- Associate Professor, Civil and Environmental Engineering
- Department Chair, Civil and Environmental Engineering
Dr. Elhajjar is a Fulbright scholar and tenured associate professor at the College of Engineering and Applied Science at the University of Wisconsin in Milwaukee. His experiences include senior positions in composite quality, certification, and build reliability engineering at Boeing and SpaceX. Dr. Elhajjar was a structural analyst on the Boeing 787 Dreamliner program where he was the lead engineer on the effects of the composite manufacturing defects program for the 787-fuselage structure. He developed various approaches for the structural assessment of composite structures with manufacturing defects. More recently in 2018, he led a similar role with SpaceX to build reliability of composite structures used in the Falcon 9 and Falcon Heavy Vehicles. Dr. Elhajjar was selected as a Fulbright Scholar to the Università Degli Studi di Trento in Italy in 2016 at the Department of Industrial Engineering for a teaching and research appointment in composite materials. He is the author of the book Composite Structures: Effects of Defects.
- PhD, Civil Engineering, Georgia Institute of Technology, 2004
- MS, Civil Engineering, University of Texas at Austin, 2000
- BS, Civil Engineering, University of Nebraska Lincoln-Omaha, 1998
- Effects of defects in polymer based composite structures, sustainable composite materials from renewable and fully recyclable systems
- Full field non-destructive testing methods
- Fracture mechanics (micro and nano composites)
- Smart composites for stress sensing
- Dielectric elastomer composites
- Magnetostrictive composites
- Coupled mechanics of composites
- Composites for infrastructure applications
- Law, C.T., Yermakov, A., Thompson, A., Coaty, C., Sabo, R., and Elhajjar, R., Flexible Magnetostrictive Nanocellulose Membranes for Actuation, Sensing and Energy Harvesting Applications. Frontiers in Materials, 2020. 7: p. 38. https://doi.org/10.3389/fmats.2020.00038
- Rigotti, D., Elhajjar, R., & Pegoretti, A. (2019). Adiabatic effects on the temperature and rate dependency of the fracture toughness of an ethylene-fluoroethylene film. Engineering Fracture Mechanics, vol. 24, pp.260-269.
- Elhajjar, R., Law, C.T. and Pegoretti, A., (2018), Magnetostrictive polymer composites: recent advances in materials, structures and properties. Progress in Materials Science, vol. 97, pp 204-229.
- Yang, P., Law, C.T., Elhajjar, R., (2017) Full-Field Infrared Phase Sensitive Thermography for Microstructural Investigation of Giant Magnetostrictive Materials, Mechanics of Advanced Materials and Modern Processes, vol. 3, no.1 p.10.
- Ning Z., Liu, R., ElHajjar, R., Wang, F.,(2017) Micro-modeling of thermal properties in carbon fibers reinforced polymer composites with fiber breaks or delamination. Composites B, v.114, pp.247-255.
- Van Dyke, S., Titi, H., & El-Hajjar, R. (2017). Comparison of California Bearing Ratio and Pin Puncture Strength Testing Used in the Evaluation of Geotextiles. Transportation Research Record: Journal of the Transportation Research Board, (2656), 1-11.
- Paneerselvam, S., Samad, W., Venkatesh, R., Song, K., Elhajjar, R, and Rowlands, R., (2017) Displacement-based experimental stress analysis of a circularly-perforated asymmetrical isotropic structure, Experimental Mechanics, 57 (1), pp 129-142.
- Sabo, R., Yermakov, A., Law, C., and Elhajjar, R., (2016) Nanocellulose enabled electronics, energy harvesting devices, smart materials and sensors: a review. Journal of Renewable Materials, 4(5): 297-312.
- Tabandeh-Khorshid, M., Schultz, B., Rohatgi, P., Elhajjar,R., (2016) The diametrically loaded cylinder for the study of nanostructured aluminum-graphene and aluminum- alumina nanocomposites using digital image correlation. Frontiers in Materials, 09 May 2016 | http://dx.doi.org/10.3389/fmats.2016.00022
- Al-Hajjeh, A., Lynch, E., Law, C. T., & El-Hajjar, R. (2016). Characteristics of a Magnetostrictive Composite Stress Sensor. IEEE Magnetics Letters, 7, 1-4.
- Elhajjar, R., and Shams, S. (2016). A new method for limit point determination in composite materials containing defects using image correlation. Composites Science and Technology. 122, 140-148,
- Shams, S., Yang, P., and Elhajjar, R. (2016). Damage Initiation and Fatigue Behavior of Carbon-Fiber Composite Disk Springs. SAE Int. J. Mater. Manf. 9(1):181-186,
- Elhajjar, R. F., Shams, S. S., Kemeny, G. J., & Stuessy, G., (2016), A hybrid numerical and imaging approach for characterizing defects in composite structures. Composites Part A: Applied Science and Manufacturing. 2016, 81, 98-104,
- Erfanian-Naziftoosi, H. R., Shams, S. S., & Elhajjar, R. (2016). Composite wave springs: Theory and design. Materials & Design, 95, 48–53
- Elhajjar, R. and Haj-Ali, R., (2016), “Thermoelastic stress analysis for detecting wrinkles and associated resin pockets in polymer composites,” Challenge Journal of Structural Mechanics, 2 (4), 246–247
- 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.
- Elhajjar, R., Grant, P., and Ashforth, C., Composites Structures: Effects of Defects, Wiley, Hoboken, NJ. 2018
Awards, Honors and Societies
- Tau Beta Pi Engineering Honor Society
- Phi Kappa Phi Honor Society