Axial Compressive Properties of Carbon/Glass Thermoplastic Epoxy Hybrid Composite Rods
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JMEPEG https://doi.org/10.1007/s11665-020-04981-w
Axial Compressive Properties of Carbon/Glass Thermoplastic Epoxy Hybrid Composite Rods Kimiyoshi Naito and Chiemi Nagai (Submitted May 18, 2020; in revised form June 25, 2020) In this study, the axial compressive properties and fracture behavior of car-bon/glass thermoplastic epoxy hybrid composite rods were investigated. The hybrid composite rods are cut, then glass fabric/epoxycomposite wrapping is applied by the wet hand layup method at each end of the specimens. The results show that the induced strain is linearly proportional to the applied stress until failure. This test method is effective in evaluating the axial compressive properties of the hybrid composite rods. The test results reveal an increase in the axial compressive modulus and strength of the hybrid composite rods as the volume fraction of the carbon fiber increases. However, a decrease in the volume fraction of the voids resulted in an increase in the axial compressive strength and thereby an increase in the Weibull shape parameter. The observed fracture surfaces showed shear cracks of the matrix at the fiber bundle intersections due to the braiding structures. Observing the internal fractures also revealed the occurrence of the micro-buckling and fiber kinking of the carbon fiber bundles. Keywords
axial compressive properties, failure analysis, hybrid composite rods, mechanical testing, thermoplastic epoxy
1. Introduction The high weight and poor corrosion resistance of steels have been a problem in their applications in tension cables (Ref 1-3). Consequently, the use of fiber-reinforced polymer matrix composites has been proposed (Ref 4-6). Currently, thermosetting epoxy resins are most often used for FRP tendons (Ref 79); however, the brittle nature of thermosetting polymers such as epoxy is an important issue that makes them less viable for certain applications. Conversely, fiber-reinforced thermoplastic matrix composites (FRTP) can potentially be post-formed and recycled, but their manufacturing is usually an energy-intensive process due to the high temperatures and pressures necessary for impregnating high molecular weight polymers (Ref 10). Novel carbon/glass thermoplastic epoxy hybrid composite rods were developed using a new thermoplastic epoxy resin (Ref 11, 12), and Naito et al. investigated the morphology and tensile properties of the hybrid composite rods (Ref 13); the results are summarized in Fig. 1 and Table 1. Tension cables consist of rods spun or twisted together to form complex structures, meaning that the stress state during use would be more complex than uniaxial tension. Additionally, such cables can be used as concrete reinforcement (in the absence of prestress) in which axial compressive stresses arise. Therefore, in addition to the tensile properties of the hybrid
Kimiyoshi Naito and Chiemi Nagai, Research Center for Structural Materials, Polymer Matrix Hybrid Composite Materials Group, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047,
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