研究目的
To study the stress field around graphene nanoplates coated carbon fiber strand reinforced in a polymer matrix using photoelasticity method, analyzing stress distribution, concentration, and the effect of fiber orientation on stress sharing and interfacial adhesion.
研究成果
The photoelastic analysis revealed strong fiber/matrix adhesion indicated by bent isochromatics. Fiber orientation at 90° was most effective in stress sharing, reducing indirect tensile stress. Orthotropic fringe orders differed from isotropic ones, and stress patterns varied with orientation, with 0° orientation behaving similarly to pure epoxy. The methods of Jacob and Sampson provided comparable results for 45° orientation, but differed for others, highlighting the importance of transverse stress considerations.
研究不足
The study is limited to diametrical compression loading and specific fiber orientations; it does not cover other loading conditions or composite configurations. The photoelastic method assumes birefringence and may have complexities for orthotropic materials. Sample fabrication might introduce slight bending in the fiber strand, affecting stress patterns.
1:Experimental Design and Method Selection:
The study used photoelasticity to map stress fields in composites under diametrical compression. Theoretical models based on rule of mixture and Hertz relations were employed for stress calculations.
2:Sample Selection and Data Sources:
Carbon fiber strand (
3:4 mm diameter, 40 fibers) coated with graphene nanoplates/epoxy mixture (1 wt% GnPs) was reinforced in epoxy matrix. Pure epoxy and composite samples were fabricated. List of Experimental Equipment and Materials:
Circular polariscope (GUNT HAMBURG, FL 200), sodium lamp light source, molds made of plaster of paris, epoxy resin (DGEBA, PL 411), curing agent (PH 861), stirrer, weights (250 g).
4:Experimental Procedures and Operational Workflow:
Samples were fabricated by coating fiber strand, embedding in epoxy, curing for 24 hours, polishing to mid-plane, and loading under diametrical compression. Isochromatic fringe patterns were captured at various loads for different fiber orientations (0°, 45°, 90°).
5:Data Analysis Methods:
Fringe orders were analyzed using isotropic and orthotropic stress-optic laws. Stresses were calculated theoretically and compared with experimental values from Jacob and Sampson methods.
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