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Journal of the Korea Concrete Institute

J Korea Inst. Struct. Maint. Insp.
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  • Korea Citation Index (KCI)

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Title Study on Tensile Properties of Carbon Fiber Reinforced Polymers (CFRP) Laminate with Strain Distribution
Authors 김윤곤(Yun-Gon Kim)
DOI https://doi.org/10.11112/jksmi.2020.24.6.25
Page pp.25-33
ISSN 2234-6937
Keywords 탄소섬유보강폴리머; 시편시험; 변형률분포; 환산변형률; 유효변형률 carbon fiber reinforced polymers; coupon test. strain distribution; converted strain; effective strain
Abstract To investigate the relationship between strain distribution and tensile properties of brittle material, five types of tensile coupon of carbon fiber reinforced polymer (CFRP) modified the tab portion in order to have a strain distribution including S0, SD1, SD2, SV1, SV2 were tested. The ultimate stress and strain of SD2 and SV2 which was intended to have larger strain distribution were smaller than those of SD1 and SV1, that was more clearly shown in the test results of the symmetric coupons (SV series) than the asymmetric coupons (SD series). In addition, the ultimate stress and strain of most coupons with strain distribution in this study were decreased when compared to the control group with uniform strain. These results were analyzed in various ways through 1) the average of the strain values directly measured by the strain gages, 2) the converted strain calculated by dividing the total deformation by the effective length, and 3) the ultimate effective strain derived from both the elastic modulus and the ultimate load. The values measured by strain gage indicates response of the local region precisely, but it does not represent the response from whole section. However, the converted strain and effective strain can supplement disadvantage of gage because they represent the average response of whole section. In particular, the effective strain can provide rupture strain conservatively, which can be utilized in practice, when the value obtained by strain gage was not effective due to gage damage or abnormal gage readings near ultimate load. This value provides a value that can be used even when partial rupture has occurred and is reasonably useful for specimens with strain distribution.