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Research on the Strength of Carbon Fiber Rope Based on Theoretical Analysis and Experiment

Author: BaiJinZeng
Tutor: JinWenCheng
School: Huazhong University of Science and Technology
Course: Bridge and Tunnel Engineering
Keywords: prestressed concrete carbon fiber parallel-layout fiber bundles strength characteristics renormalization group
CLC: U444
Type: Master's thesis
Year: 2011
Downloads: 54
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Abstract

FRP has showed good mechanical properties. In recent years, Scholars have studied this composite material and constructed some experimental bridges. By the impact of raw materials and production process, the tensile strength of FRP is usually lower than fiber. Furthermore, because of the presence of resin based materials, it is not easy to change the shape of FRP bars. At the same time, bending at the steering block caused strength reduction. In short, FRP bars are not suitable for in-body curve prestressed reinforcement. Using parallel-fiber bundles as an alternative to FRP bars to press compression stress may overcome the shortcomings.The strength characteristic of the parallel-layout carbon fiber bundles and its experimental phenomena was introduced in this paper. All the work is as followed: Firstly, by summarizing the strength statistical characteristics of fibers and experience,we found the incidence of fracture has randomness. The cumulative probability distribution function of the fiber obeys weibull distribution. Experimental phenomena showed the district discreteness of carbon fiber. In addition, we evaluated tensile elastic modulus by the constitutive-curve.Secondly, according to the statistical characteristics of carbon fiber, we deduced the force-strain function and load-L function. According to the experimental results, we estimated the parameters of the weibull description which was uesd to descript the tensile property of carbon fiber.Thirdly, for the fiber bundle which was made of same kind fiber, we derived expressions of expectation value standard deviation to failure strength. Furthermore, we obtained permissible value of fiber bundle. However, sometimes, we tend to use blend fibers to braided fiber rope so that it is hard to estimate the load-carrying capacity only by probability theory method. This thesis proposed an idea based on renormalization to estimate the critical load of fiber bundles.Fourthly, we manufactured test carbon fiber ropes to do tension test. In order to anchor, we cured the both ends of the samples to a shape matching with the anchors where the middle part of the ropes did not contain epoxy resin. According to the study of the failure patterns, we learnt that all failure occurred near curing interface; the average intensities are lower than calculated values (Large diameter, low intensity).In summary, weibull description met the practical well. The existence of the curing interface reduced the strength of the ropes. it would be better if we improve the production process.

Research on the Strength of Carbon Fiber Rope Based on Theoretical Analysis and Experiment

Abstract

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