• Title/Summary/Keyword: 열습

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Failure Behavior of Pin-jointed Carbon/Epoxy Composites under Hygrothermal Environmentals (열습환경을 고려한 탄소섬유/에폭시 복합재의 핀 체결부 파괴거동)

  • Kim, Chan-Gyu;Hwang, Young-Eun;Yoon, Sung-Ho
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2012.05a
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    • pp.411-413
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    • 2012
  • This study has been investigated about hygrothermal environmental effects on the pin-joined carbon/epoxy composites through acoustic emission technique. The specimens were classified as three types for pin loading test : Base (before immersion), RT (room temperature immersion), HT ($75^{\circ}C$ immersion). As a results, the bearing strength of RT specimens was weakly decreased than that of base specimens. The bearing strength of HT specimens was greatly decreased than that of Base and RT specimens due to effects of simultaneous moisture and higher temperature. Also, the results from cumulative hit of acoustic emission indicated that AE events induced by matrix cracks of HT specimens was lower than that of base specimens.

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Failure Behavior of Pin-jointed Composites under Hygrothermal Environments (열습환경을 고려한 핀 체결부 복합재 파괴거동)

  • Kim, Changyu;Hwang, Youngeun;Yoon, Sungho
    • Journal of the Korean Society of Propulsion Engineers
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    • v.17 no.2
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    • pp.31-38
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    • 2013
  • This research analyzed the acoustic emission signals collected from the pin loading tests and investigated the effect of hygrothermal exposure on the fracture behavior of the pin-jointed carbon fiber/epoxy composites. The composite specimens include: the Base specimen that has not been exposed to any environments, the RT specimen that has been immersed in room temperature water, and the HT specimen that has been immersed in high temperature water. According to the pin loading test, the RT and the HT specimens showed 2.2% and 13% decreases in the bearing strength compared to the Base specimen, respectively. The analysis of the acoustic emission signals showed different fracture acceleration points for three types of the specimens. Furthermore, for the RT and the HT specimens, the event from the matrix crack signals in the composites decreased. This shows the effect of the hygrothermal conditions on the acoustic emission signals. Additionally, upon investigating the fracture behaviors of the pin-jointed composites, the exposing specimens to hygrothermal environments decreases the interfacial characteristics of the composites.

The Influence of Hygrothermal Effect to Residual Strength GFRP Composites (열습효과가 GFRP의 잔류강도에 미치는 영향)

  • 한길영;이동기;김이곤;김기성
    • Journal of Ocean Engineering and Technology
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    • v.9 no.1
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    • pp.57-62
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    • 1995
  • The hygrothermal effect on three different types of Glass/Polypropylene was investigated under the environment of 4$0^{\circ}C$ distilled water. The residual strength of Glass/Polypropylene with randomly oriented and fiber content of 4-wt%(R40) was found stable under the moisture content of 0.2%. In this case, the maximum moisture content was 0.53%. On the other hand, Glass/Polypropylene with unidirection and 42wt%(U42) and 50st%(U50) fiber content, respectively, showed the residual strength less stable than R40. However, the maximam moisture contents were 0.52% and 0.45% respectively.

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Strength Evaluation on CFRP Hat-shaped Sectional Members According to Changes in Temperature Under Hygrothermal Environment (온도 변화에 따른 열습 환경하에서의 CFRP 모자형 단면부재의 강도평가)

  • Yang, Yongjun;Kook, Hyun;Yang, Inyoung
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.21 no.6
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    • pp.892-896
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    • 2012
  • CFRP composites with light weight, high strength, and high elasticity by comparing with metal are widely used rather than previous steel plates. However, CFRP composite material has the weakness at hydrothermal and collapsed impact environment. Especially, moisture absorption into composite material can change molecule arrangement and chemical properties under hydrothermal environment. And static collapse experiment is the research in the differences of absorbed energy and deformation mode between moisture and non-moisture absorbed specimens. This study is compared and analyzed on the progress change of moisture absorption ratio after setting up the temperatures of 60 and 80 degrees C in order to comprehend how the change in the temperature influences on moisture absorption status inside CFRP composite materials.

Collapse Characteristics of CFRP Hat Shaped Members under the Hygrothermal Environment According to Stacking Angle (열습환경 하에서의 적층각도 변화에 따른 CFRP 모자형 단면부재의 압궤특성)

  • Yang, Yong-Jun;Yang, In-Young;Sim, Jae-Ki
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.18 no.5
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    • pp.507-513
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    • 2009
  • It is important to satisfy the requirements and standards for the protections of passengers in a car accident. There are lots of studies on the crushing energy absorption of structure members in automobiles. We have investigated collapse characteristics and moisture absorption movements of CFRP(Carbon Fiber Reinforced Plastics) hat shaped sectional members when CFRP laminates are under the hygrothermal environment. The absorbed energy, mean collapse load and deformation mode were analyzed for side members which absorbed most of the collision energy. Therefore we have made a static collapse experiment to research into the difference of absorbed energy and deformation mode between moisture absorbed specimen and non-moisture absorbed specimen.

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A Study on the Bearing Strength of Bolt Jointed Section for Composite Aircraft Radome Under Hygrothermal Environments (열습환경을 고려한 항공기용 레이돔 볼트 체결부의 베어링 강도에 관한 연구)

  • Kim, Ho Il;Ryu, Guh Yun;Kim, Joon;Kim, Kwang Min;Lee, Kyu Song;Park, Young Ju;Park, Byum Jun;Ryu, Hong Kyun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.41 no.8
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    • pp.759-764
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    • 2017
  • This research investigated the hygrothermal effect on the strength of bolt jointed section and moisture contents of composites exposed to hygrothermal environment for composite aircraft radome. The decrease in strength in the test environment is mainly attributed to the change in the material properties of the matrix due to temperature and moisture. The composite specimens were tested in three different environmental conditions: RTD(room temperature and dry), CTD(cold temperature and dry) and ETW(elevated temperature and wet). The failure mode of the bolt jointed composite specimens were studied using tests and finite element analysis. Finite element analysis reasonably predicted the failure load and mode of the joints. A reliability-based design was carried out for the bolt jointed composites of radome.

Hygrothermal and Impact Damage Evaluation of CFRP Hat shaped sectional members with Stacking Angle Variation (적층각도 변화를 갖는 CFRP 모자형 단면부재의 열습 및 충격손상 평가)

  • Yang, Yong-Jun;Sim, Jae-Ki
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.19 no.6
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    • pp.782-789
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    • 2010
  • It is important to satisfy the requirements and standards for the protections of passengers in a car accident. There are lots of studies on the crushing energy absorption of a structure member in automobiles. In this paper, we have studied to investigate collapse characteristics and moisture absorption movements of CFRP( carbon fiber reinforced plastics) structure members when CFRP laminates are under the hygrothermal environment. In particular, the absorbed energy, mean collapse load and deformation mode were analyzed for CFRP members which absorbed most of the collision energy. Also, variation of stacking angle is important to increase the energy absorption capability. The purpose of this study is to evaluate the strength reduction and moisture absorption behavior of CFRP hat shaped member. Therefore we have made a impact collapse experiment to research into the difference of absorbed energy and deformation mode between moisture absorbed specimen and non-moisture absorbed. As a result, the effect of moisture absorption and impact loads of approximately 50% reduction in strength are shown.

Influence of Hygrothermals on Residual Fatigue Bending Strength of CFRP Composite Laminates (CFRP적층재의 잔류피로굽힘강도애 미치는 열습의 영향)

  • 박노식;임광희;양인영
    • Journal of the Korean Society of Safety
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    • v.12 no.2
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    • pp.27-36
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    • 1997
  • This paper evaluates the static and fatigue bending strengths of CFRP (carbon fiber reinforced plastic) laminates subjected to hygrothermals. The specimens which had different stacking composition, orthotropic and quasi-isotropic laminated plates, were prepared for this experiment. A steel ball launched by the air gun collides against CFRP laminates to generate impact damages, and the 3-point fatigue bending test is carried out by using the impacted laminates to investigate the influence of hygrothermals on the effect on the residual bending fatigue strength of CFRP laminates.

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Hygrothermal Effect of Salt-Water Environments on Mechanical Properties of Carbon/Epoxy Composites (탄소섬유/에폭시 복합재의 기계적 특성에 미치는 염수환경의 열습 영향)

  • Hwang, Young-Eun;Yoon, Sung-Ho
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.10
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    • pp.1261-1266
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    • 2012
  • In this study, salt-water immersion tests were experimentally performed for up to 12 months to investigate the hygrothermal effect of salt-water environments on the mechanical properties of carbon/epoxy composites. The composites were manufactured by laminating prepregs composed of carbon plain-woven fabric and epoxy resin. The specimens were subjected to temperatures of 35, 55, and $75^{\circ}C$ while being exposed to the salt-water environments. Mechanical test results showed that the tensile modulus and tensile strength decreased at a small rate, and the compressive modulus and compressive strength decreased at a relatively larger rate, as the exposure temperature and time increased. The rate of decrease in compressive strength became larger as the exposure temperature became higher. This is because a higher environmental temperature accelerates the salt-water uptake; this, in turn, reduces the compressive strength more rapidly.

Collapse Characteristics of CFRP Hat Shaped members According to Variation of Interface Numbers under the Hygrothermal Environment (고온.고습 환경 하에서의 계면수 변화에 따른 CFRP모자형 단면 부재의 압궤특성)

  • Yang, Yong-Jun;Cha, Cheon-Seok;Yang, In-Young
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.18 no.3
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    • pp.241-247
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    • 2009
  • It is important to satisfy the requirements and standards for the protections of passengers in a car accident. There are lots of studies on the crushing energy absorption of a structure members in automobiles. We have studied to investigate collapse characteristics and moisture absorption movements of CFRP(Carbon Fiber Reinforced Plastics) hat shaped sectional members when CFRP laminates are under the hygrothermal environment. In particular, the absorbed energy, mean collapse load and deformation mode were analyzed for side members which absorbed most of the collision energy. Variation of CFRP interlaminar numbers is important to increase the energy absorption capability. Therefore we have made a static collapse experiment to research into the difference of absorbed energy and deformation mode between moisture absorbed specimen and non-moisture absorbed.

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