• Title/Summary/Keyword: Woven CFRP

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Crack Propagation and Acoustic Emission Evaluation of Plain Woven CFRP Laminate Composites for Fiber Orientation (섬유방향 변화에 따른 직물구조 CFRP 적층판의 균열진전 및 AE평가)

  • Yun, Yu-Seong;Kwon, Oh-Heon
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.364-369
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    • 2003
  • Crack propagation and AE characteristics of CFRP plain woven laminate composites are examined with acoustic sensor by AEDSP 32/16 board in PC system. AE signals are measured during the fracture behavior tests. The purpose of study is the estimation of the crack extension behavior effected between three kinds of fiber orientation for plain woven CFRP laminate composite and the relationship between AE characteristics and load-displacement curves and crack extension length.

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Evaluation of the Damage Mechanism in CFRP Composite Using Computer Vision

  • Kwon, Oh-Heon;Xu, Shaowen;Sutton, Michael
    • Journal of Advanced Marine Engineering and Technology
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    • v.34 no.5
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    • pp.686-694
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    • 2010
  • Continuing progress in high technology has created numerous industrial applications for new advanced composite materials. Among these materials, carbon fiber-reinforced plastic (CFRP) laminate composite is typically used for low-weight carrying structures that require high specific strength. In this study, the damage mechanism of a compact tension (CT) specimen of woven CFRP laminates is described in terms of strain and displacement changes and crack growth behavior. The digital image correlation (DIC) method (which is employed here as a computer vision technique) is analyzed. Acoustic emission (AE) characteristics are also acquired during fracture tests. The results demonstrate the usefulness of these methods in evaluating the damage mechanism for woven CFRP laminate composites. From the results, we show these methods are so useful in order to evaluate the damage mechanism for woven CFRP laminate composites.

The Effect of Load Orientation for Crack Propagation and Acoustic Emission Evaluation on Plain Woven CFRP (평직 CFRP 복합재료의 균열진전 및 AE평가에 미치는 하중방향 영향)

  • Kwon, Oh-Heon;Yun, Yu-Seong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.4
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    • pp.443-452
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    • 2004
  • In recent year, composite materials are increasingly used in various fields of engineering because of its superior properties. The relationships of between crack propagation and AE characteristics fer CFRP plain woven laminate composites are examined. AE signals are measured during the fracture behavior tests. The purpose of study is to estimate the crack extension behavior with AE characteristics according to the load orientation fur plain woven CFRP laminate composite.

Evaluation of Material Properties about CFRP Composite Adapted for Wind Power Blade by using DIC Method (풍력발전기 블레이드 적용 CFRP 복합재료의 DIC 방법에 의한 재료특성치 평가)

  • Kang, J.W.;Kwon, O.H.;Kim, T.K.;Cho, S.J.
    • Journal of Power System Engineering
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    • v.14 no.5
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    • pp.17-23
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    • 2010
  • In recent, the capacity of a commercial wind power has reached the range of 6 MW, with large plants being built world-wide on land and offshore. The rotor blades and the nacelle are exposed to external loads. Wind power system concepts are reviewed, and loadings by wind and gravity as important factors for the mechanical performance of the materials are considered. So, the mechanical properties of fiber composite materials are discussed. Plain woven fabrics Carbon Fiber Reinforced Plastics (CFRP) are advanced materials which combine the characteristics of the light weight, high stiffness, strength and chemical stability. However, Plain woven CFRP composite have a lot of problems, especially delamination, compared with common materials. Therefore, the aim of this work is to estimate the mechanical properties using the tensile specimen and to evaluate strain using the CNF specimen on plain woven CFRP composites. For the strain, we tried to apply to plain woven CFRP using Digital Image Correlation (DIC) method and strain gauge. DIC method can evaluate a strain change so it can predict a location of fracture.

The Evaluation of Interlaminar Fracture Toughness and AE Characteristics in a Plain Woven CFRP Composite with ENF Specimen (ENF 시험편을 이용한 평직 CFRP의 층간파괴인성 및 AE 특성 평가)

  • Yun, Y.S.;Kwon, O.H.
    • Journal of Power System Engineering
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    • v.10 no.2
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    • pp.117-123
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    • 2006
  • Woven fabrics composites are used as primary structural components in many applications because of their superior properties that offer high specific strength and stiffness. However, the complexity of the fabric structure makes understanding of their failure behavior very difficult. Also, laminate woven fabrics CFRP have unique failure mechanisms such as fiber bridging, fiber/matrix crack and so on. In particular, the delamination phenomenon of the composite materials is one of the most frequent failure mechanisms. So, we estimated interlaminar fracture and damage in composites using as ENF specimen by a 3 point bending test. And AE characteristics were examined for crack propagation on plain woven CFRP. We obtained the following conclusions from the results of the evaluation of the 3 point bending fracture test and AE characteristic estimation. AE counts of maximum crack length were obtained as $85.97{\times}10^4\;and\;93{\times}10^3\;for\;a_0/L=0.3$ and 0.6, respectively. Also the maximum amplitudes were over 80dB at both $a_0/L=0.3\;and\;0.6$. $G_{IIc}$ at that's $a_0/L$ ratio were obtained with $1.07kJ/m^2\;and\;3.79kJ/m^2$.

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The Strength Evaluation on Repaired Plain Woven CFRP Composite with a Circular Hole

  • Kwon, Oh-Heon;Park, Jun-Ho
    • International Journal of Safety
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    • v.8 no.1
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    • pp.1-5
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    • 2009
  • The CFRP composite has unique properties that offer high strength and stiffness, even though it has light weight. Therefore it can be used in many industrial applications. When mechanical fasteners are used for joining composites, high stress concentrations appear near the edge of holes prepared for accommodating structural bolts and rivets. This presence of high stress concentrations can be a source of damage. The aim of this work is to evaluate fracture behavior and patterns of plain woven CFRP with circular hole and repairing patch element. The maximum strength and pattern for the plain woven carbon composite specimen with the repaired circular hole were examined. From the results, we show that repairing of the CFRP composite specimen with ($\pi$) 3~5 mm of circular hole diameter results in load rising effect and the repairing is more effective as bigger hole specimen.

Mode II Interlaminar Fracture Toughness of Hybrid Composites Inserted with Different Types of Non-woven Tissues (종류가 다른 부직포가 삽입된 하이브리드 복합재료의 모드 II 층간파괴인성)

  • Jeong, Jong-Seol;Cheong, Seong-Kyun
    • Composites Research
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    • v.26 no.2
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    • pp.141-145
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    • 2013
  • The mode II interlaminar fracture toughness was evaluated for CFRP laminates with different types of nonwoven tissues and the source of increased mode II interlaminar fracture toughness was examined by SEM analysis in this paper. The interlaminar fracture toughness in mode II is obtained by an end notched flexure test. The experiment is performed using three types of non-woven tissues: 8 $g/m^2$ of carbon tissue, 10 $g/m^2$ of glass tissue, and 8 $g/m^2$ of polyester tissue. On the basis of the specimen with no non-woven tissue, interlaminar fracture toughness on mode II at specimens inserted with non-woven carbon and glass tissues and polyester tissues increases as much as 166.5% and 137.1% and 157.4% respectively. The results show that mode II interlaminar fracture toughness of CFRP laminates inserted with nonwoven tissues increased due to the fiber bridging, fiber breakage, and hackle etc. by SEM analysis.

Study on Fastened Properties by Applied to CFRP Laminates of Subminiature Screw (초소형나사의 CFRP 적층판 적용에 따른 체결특성에 관한 연구)

  • Choi, Byung Hui;Kim, Ho Joong;Kim, Ji Hoon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.11
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    • pp.1239-1243
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    • 2014
  • This paper presents the application of carbon-fiber-reinforced polymer (CFRP) for the damage absorption and optimal design of portable smart devices to close in life. CFRP specimens are subjected to a tensile test to estimate their mechanical properties in terms of the stacking angles. Further, the screw reverse torque and screw torque at each stacking angle are determined using a torque tester after tapping holes on the CFRP specimens. Two experiments are performed for comparing their results in order to determine optimal conditions. In the tensile test, a woven specimen is found to have the highest strength and stiffness. In the case of the woven specimen, no difference is observed even when it is applied to prevent loosening of the coating. And average result value was excellent.

The Evaluation of Interlaminar Fracture Toughness and AE Characteristics in a Plain Woven CFRP Composite with DCB Specimen (DCB 시험편의 평직 CFRP 복합재 층간파괴인성 및 AE 특성 평가)

  • Yun Yu-Seong;Kwon Oh-Heon
    • Journal of the Korean Society of Safety
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    • v.20 no.1 s.69
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    • pp.49-54
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    • 2005
  • Recently, many kinds of advanced composite materials have been used in various industry fields. Among them, fabric CFRP composites are being used as primary structural components in many applications because of their superior properties. However, the complexity of the fabric structure makes understanding of their failure behavior very difficult. The mechanical strength and crack propagation of plain woven carbon fiber fabric laminate composites are examined by acoustic emission(AE) method. AE signals are acquired during the tensile test and fracture tests. Thus, the relationship between AE signal and mechanical behavior curves and crack extension length are shown. Also the interlaminar fracture toughness in terms of AE characteristics are discussed in viewpoint of crack propagation behavior.

Effect of non-woven tissues on interlaminar fracture toughness of composite laminate (부직포가 복합적층판의 층간파괴인성에 미치는 효과)

  • 김영배;정성균;강진식;김태형
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2000.11a
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    • pp.110-114
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    • 2000
  • The Interlaminar fracture behavior of hybrid composite with non-woven carbon tissue was investigated under Mode I (DCB) and Mode II (ENF) loading condition. Hybrid composites were manufactured by means of inserting a non-woven tissue between prepreg layers. Two kinds of specimens were prepared from [0]$_{24}$ and [$0_{12}/0_{12}$]. Where, the symbol "/" means that a non-woven carbon tissue was located at 0/0 mid-plane of the specimen. The interlaminar fracture toughness of hybrid composites was compared with that of CFRP. The fracture surfaces of the specimens were observed using optical microscope and SEM, and the failure mechanism was discussed. The hybrid laminates, which are made by inserting non-woven carbon tissue between layers, were shown to be effective to remarkably improve Mode II fracture toughness.toughness.

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