Short Communications | Challenge Journal of Structural Mechanics

Thermoelastic stress analysis for detecting wrinkles and associated resin pockets in polymer composites

Rani Elhajjar, Rami Haj-Ali


DOI: https://doi.org/10.20528/cjsmec.2016.11.025
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Abstract


A thermos elastic stress analysis method is proposed consisting of an array of infrared measurement sensors used for evaluation the wrinkling defects and associated resin pockets in a fiber reinforced polymer (FRP) composite structure. Wrinkling or fiber waviness defects results when out of plane distortions occur in some or all of the composite layers of the laminate. The wrinkles result in significant reductions of mechanical properties in the composite structure. The method involves instrumentation and device for application of internal energy in the material such as transient or cyclic mechanical excitations. These external excitations are induced in a prescribed or measurable cyclic or transient function of time. Infrared measurements from the surface of the composite are synchronized with the applied excitation energy. The results are used to provide for a map detailing the inner wrinkle defects and associated resin pockets in the laminated composite structure.


Keywords


thermoelasticity; experimental stress analysis; effects of defects; composites

References


El-Hajjar RF, Petersen DR (2011). Gaussian function characterization of unnotched tension behavior in a carbon/epoxy composite containing localized fiber waviness. Composite Structures, 93(9), 2400-2408.

https://doi.org/10.1016/j.compstruct.2011.03.029

Elhajjar R, Haj-Ali R, Wei B (2014). An infrared thermoelastic stress analysis investigation for detecting fiber waviness in composite structures. Polymer-Plastics Technology and Engineering, 53, 1251–1258.

https://doi.org/10.1080/03602559.2014.886116

Rauch BJ, Rowlands RE (1993). Thermoelastic Stress Analysis in Handbook on Experimental Mechanics. Kobayashi AS, ed., SEM.

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Peer-review under responsibility of the organizing committee of ICEM17.


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