Piezoresistive Sensing of Strain and Damage in Carbon/Epoxy Rectangular and I-shaped Cross-section Beams in Flexure
The strain and damage sensing capabilities of a carbon fiber/epoxy composite subjectedto monotonic and incremental cyclic flexural loading is investigated using theelectrical resistance approach. The piezoresistive sensitivity of the carbon fiber/epoxycomposites were first characterized using rectangular cross-section specimens andthen application of the electrical resistance approach was extended to an I-shapedcross-section laminated composite. The change in the electrical resistance of the specimenswas simultaneously monitored on both the tensile and compressive sides whilethe specimens were tested under flexural loading. On the tensile side, the positive electricalresistance change (ΔR) showed a linear trend for small deformations (less than0.3% strain) and increased in a nonlinear fashion for larger deformations. In contrast tothe tensile side, ΔR on the compressive side showed a nonlinear and non-monotonicbehavior. Initially, ΔR decreased for low values of deformation (less than 0.3% strain),leveled off at the onset of the specimen’s compressive failure, and then increased upto complete failure. Correlations between abrupt changes in ΔR and indications ofcomposite damage are confirmed with scanning electron microscopy. Carbon fibersin both rectangular and I-shaped cross-section carbon/epoxy specimens are capableof sensing tensile and compressive strain, and adequately capture the onset and progressionof failure by fiber micro-buckling, formation of kink bands, and delamination.The cross-section properties (e.g. stiffness and layup sequence) affect the piezoresistiveand damage sensitivity, with the stiffer I-shaped cross-section being less sensitiveto ΔR than standard specimens of rectangular cross-section. ΔR under cyclic flexuralloading for both tensile and compressive sides showed a permanent change with applieddeformation after each cycle, indicating first the release of residual stresses andthen damage.
| Main Authors: | , , , , |
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| Format: | info:eu-repo/semantics/article biblioteca |
| Language: | eng |
| Subjects: | info:eu-repo/classification/Autores/CARBON FIBER, info:eu-repo/classification/Autores/I-BEAM, info:eu-repo/classification/Autores/PIEZORESISTIVITY, info:eu-repo/classification/Autores/FLEXURAL LOADING, info:eu-repo/classification/cti/7, info:eu-repo/classification/cti/33, info:eu-repo/classification/cti/3312, info:eu-repo/classification/cti/331208, |
| Online Access: | http://cicy.repositorioinstitucional.mx/jspui/handle/1003/1669 |
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| Summary: | The strain and damage sensing capabilities of a carbon fiber/epoxy composite subjectedto monotonic and incremental cyclic flexural loading is investigated using theelectrical resistance approach. The piezoresistive sensitivity of the carbon fiber/epoxycomposites were first characterized using rectangular cross-section specimens andthen application of the electrical resistance approach was extended to an I-shapedcross-section laminated composite. The change in the electrical resistance of the specimenswas simultaneously monitored on both the tensile and compressive sides whilethe specimens were tested under flexural loading. On the tensile side, the positive electricalresistance change (ΔR) showed a linear trend for small deformations (less than0.3% strain) and increased in a nonlinear fashion for larger deformations. In contrast tothe tensile side, ΔR on the compressive side showed a nonlinear and non-monotonicbehavior. Initially, ΔR decreased for low values of deformation (less than 0.3% strain),leveled off at the onset of the specimen’s compressive failure, and then increased upto complete failure. Correlations between abrupt changes in ΔR and indications ofcomposite damage are confirmed with scanning electron microscopy. Carbon fibersin both rectangular and I-shaped cross-section carbon/epoxy specimens are capableof sensing tensile and compressive strain, and adequately capture the onset and progressionof failure by fiber micro-buckling, formation of kink bands, and delamination.The cross-section properties (e.g. stiffness and layup sequence) affect the piezoresistiveand damage sensitivity, with the stiffer I-shaped cross-section being less sensitiveto ΔR than standard specimens of rectangular cross-section. ΔR under cyclic flexuralloading for both tensile and compressive sides showed a permanent change with applieddeformation after each cycle, indicating first the release of residual stresses andthen damage. |
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