scholarly journals Experimental Study of the Probabilistic Fatigue Residual Strength of a Carbon Fiber-Reinforced Polymer Matrix Composite

2020 ◽  
Vol 4 (4) ◽  
pp. 173
Author(s):  
Xiang-Fa Wu ◽  
Oksana Zholobko
Keyword(s):  
Experimental Study ◽  
Tensile Strength ◽  
Carbon Fiber ◽  
Cyclic Loading ◽  
Polymer Matrix ◽  
Residual Strength ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Reinforced Polymer ◽  
Carbon Fiber Reinforced

Degradation of the mechanical properties of fiber-reinforced polymer matrix composites (PMCs) subjected to cyclic loading is crucial to the long-term load-carrying capability of PMC structures in practice. This paper reports the experimental study of fatigue residual tensile strength and its probabilistic distribution in a carbon fiber-reinforced PMC laminate made of unidirectional (UD) carbon-fiber/epoxy prepregs (Hexcel T2G190/F263) with the ply layup [0/±45/90]S after certain cycles of cyclic loading. The residual tensile strengths of the PMC laminates after cyclic loading of 1 (quasistatic), 2000, and 10,000 cycles were determined. Statistical analysis of the experimental data shows that the fatigue residual tensile strength of the PMC laminate follows a two-parameter Weibull distribution model with the credibility ≥ 95%. With increasing fatigue cycles, the mean value of the fatigue residual strength of the PMC specimens decreased while its deviation increased. A free-edge stress model is further adopted to explain the fatigue failure initiation of the composite laminate. The present experimental study is valuable for understanding the fatigue durability of PMC laminates as well as reliable design and performance prediction of composite structures.

scholarly journals Experimental investigation of the microstructures and tensile properties of polyacrylonitrile-based carbon fibers exposed to elevated temperatures in air

2019 ◽  
Vol 14 ◽  
pp. 155892501985001 ◽  
Author(s):  
Chenggao Li ◽  
Guijun Xian
Keyword(s):  
Tensile Strength ◽  
Carbon Fiber ◽  
Carbon Fibers ◽  
Elevated Temperatures ◽  
Tensile Modulus ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Reinforced Polymer ◽  
Carbon Fiber Reinforced

The elevated temperature resistance and even fire resistance of carbon fiber-reinforced polymer composites were critical concerns in many applications. These properties of a carbon fiber-reinforced polymer depend not only on the degradation of the polymer matrix but also on that of the carbon fibers under elevated temperatures. In this study, influences of elevated temperatures (by 700°C for 30 min) in air on the mechanical properties and microstructures of a carbon fiber were investigated experimentally. It was found that the tensile strength and modulus as well as the diameters of the carbon fibers were reduced remarkably when the treatment temperatures exceeded 500°C. At the same time, the content of the structurally ordered carbonaceous components on the surface of carbon fibers and the graphite microcrystal size were reduced, while the graphite interlayer spacing ( d002) was enhanced. The deteriorated tensile modulus was attributed to the reduced graphite microcrystal size and the reduced thickness of the skin layer of the carbon fiber, while the degraded tensile strength was mainly attributed to the weakened cross-linking between the graphite planes.

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