• 제목/요약/키워드: impact damages

검색결과 310건 처리시간 0.02초

고온.고습하에서 직교이방성 CFRP 복합적층판이 잔류피로 굽힘강도에 미치는 영향에 관한 연구 (A Study on Effects to Residual Fatigue Bending Strength or Orthotropy CFRP Composite Laminates under High Temperature and Moisture)

  • 임광희;양인영
    • 한국자동차공학회논문집
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    • 제8권6호
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    • pp.247-258
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    • 2000
  • It is thought that impact damages and hygrothermals can affect to CFRP (Carbon-fiber reinforced plastic) composite laminated due to the sensitivity on the composite laminated Therefore, this paper focuses on the fracture mechanisms experimentally based on a scanning acoustic microscope (SAM) when subjected to impact damages, i.e., foreign object damages(FOD), and also the influence of impact damages and hygrothermals on residual fatigue bending strength of CFRP laminates. Composite laminates used in the experiment are CF/EPOXY orthotropy laminated plates, which constist of two-interfaces [04/904]s. A steel ball launched by an air gun collides against CFRP laminates to generate impact damages. Bending fatigue tests are periodically interrupted for a nondestructive evaluation (NDE) measurement of the progrossive damages to built the fracture mechanism by impact damages, and three-point fatigue bending tests are carried out to investigate the influence of hygrothermals on the effect on the residual bending fatigue strength of CFRP laminates.

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온도변화가 CF/PEEK 적층재의 충격 후 굽힘강도에 미치는 영향 (The Effects of Temperature Change on the Bending Strength of CF/PEEK Laminates after Impact)

  • 양인영;정종안;나승우
    • 한국안전학회지
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    • 제18권2호
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    • pp.34-39
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    • 2003
  • In this paper, when CF/PEEK laminates for high efficiency space structure are subjected to FOD(Foreign Object Damage), the effects of temperature change on the impact damages(interlaminar separation and transverse crack) of CF/PEEK laminates and the relationship between residual lift and impact damages are experimentally investigated. Composite laminates used in this experiment are CF/PEEK orthotropic laminated plates, which have two-interlaces [$0^{\circ}_4/90^{\circ}_8/0^{\circ}_4$]. A steel ball launched by the air gun collides against CF/PEEK laminates to generate impact damages. And then CF/PEEK specimens with impact damages are observed by a scanning acoustic microscope under room and high temperatures. In this experimental results, various relations are experimentally observed including the delamination area vs. temperature change, the bending strength vs. impact energy and the residual bending strength vs. impact damage of CF/PEEK laminates.

온도변화가 CFRP 적층재의 충격후 잔류굽힘강도에 미치는 영향 (The Effects of Temperature Change on the Residual Bending Strength of CFRP Laminates after Impact)

  • 나승우;정종안;양인영
    • 한국안전학회지
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    • 제20권1호
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    • pp.75-80
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    • 2005
  • In this paper, when CF/EPOXY laminates for high efficiency space structure are subjected to FOD(Foreign Object Damage), the effects of temperature change on the impact damages(inter laminar separation and transverse crack) of CF/EPOXY laminates and the relationship between residual life and impact damages ale experimentally investigated. Composite laminates used in this experiment are CF/EPOXY orthotropic laminated plates, which have two-interfaces $[0^{\circ}_6/90^{\circ}_6]S$ and four-interfaces $[0^{\circ}_3/90^{\circ}_6/0^{\circ}_3]S$. CF/EPOXY specimens with impact damages caused by a steel ball launched from the air gun were observed by the scanning acoustic microscope under room and high temperatures. In this experimental results, various relations were experimentally observed including the delamination area vs. temperature change, the bending strength vs. impact energy and the residual bending strength vs. impact damage of CF/EPOXY laminates. And as the temperature of CF/PEEK laminates increases, the delaminaion areas of impact-induced damages decrease linearly. A linear relationship between the impact energy and the delamination areas were observed. As the temperature of CF/PEEK laminates increases, the delamination areas decrease because of higher initial delaminatin damage energy.

PVDF 센서신호를 이용한 Gr/Ep 적층판의 저속충격 손상탐지 (Low-Velocity Impact Damage Detection for Gr/Ep Laminates Using PVDF Sensor Signals)

  • 박찬익;김인걸;이영신
    • 한국복합재료학회:학술대회논문집
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    • 한국복합재료학회 2003년도 추계학술발표대회 논문집
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    • pp.158-162
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    • 2003
  • The PVDF(polyvinylidene fluoride) film sensor as one of smart sensors has good characteristics to detect the impact damages of composite structures. The capabilities of the PVDF film sensor for evaluating impact behaviors and damages of Gr/Ep laminates subjected to low-velocity impact were examined. From sensor signals, the specific wave-forms implying the damage were detected. The wavelet transform(WT) and Short Time Fourier Transform(STFT) were used to decompose the piezoelectric sensor signals in this study. The impact behaviors of Gr/Ep laminates were simulated and the impact forces were reconstructed using the sensor signals. Finally, the impact damages were predicted by finite element analysis with the reconstructed forces. For experimental verification, a series of low-velocity impact tests from low energy to damage-induced energy were carried-out. The extent of damage in each case was examined by means of ultrasonic C-scan and the measured damage areas were agreed well with the predicted areas by the F.E.A.

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고온에서 총격을 받는 CFRP 적층재의 총격손상과 잔류강도에 관한 연구 (A study on the Impact damages and residual strength of CFRP laminates to impact under high temperature)

  • 정종안;이상호;양인영
    • 한국안전학회지
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    • 제11권3호
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    • pp.44-52
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    • 1996
  • An experimental study on the effects of temperature change on the impact damages of CFRP aminates was made through an observation of the interrelations between the Impact energy vs. delamination area, the impact energy vs. residual bending strength, and the delamination area vs. the decreasing of the residual bending strength for CF/EPOXY and CF/PEEK composite laminates subjected to FOD (Foreign Object Damage) under high temperatures.

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접촉하중형태에 따른 복합재의 거동변화 (Behavior of Woven-glass/Epoxy Composites after Impact Loading)

  • 이재준;김병식;황성식;김태우;김찬묵
    • 한국복합재료학회:학술대회논문집
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    • 한국복합재료학회 2002년도 춘계학술발표대회 논문집
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    • pp.53-56
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    • 2002
  • External low-velocity impact loadings onto the composites cause reduction of stiffness and/or strength. The reductions indicate that internal(external) damages were developed within the composites. These damages could be matrix cracking, fiber/matrix debonding, or delamination between layers. In previous studies, damage evaluation have been done by applying secondary mechanical loading such as buckle-driven compressive, or fatigue, or flexural loadings. An evaluation method by applying indentation loadings on the composites was proposed. The load-displacement curves obtained from the indentation testing provided the extent of damages within the composites due to impact loadings.

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섬유강도와 적층구성이 CFRP적층판의 충격손상에 미치는 영향 (Influence of Fiber Strength and Stacking Sequences on Impact Damages of CFRP Composites)

  • 임광희;박노식;양인영
    • 한국자동차공학회논문집
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    • 제9권3호
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    • pp.210-220
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    • 2001
  • This paper aims at the evaluation on the characterization of CFRP laminate plates using falling weight impact tester. The experimentation was conducted on several laminates of different fiber and ply orientation. A system was built for the impact strength of CFRP laminates in consideration of stress wave propagation with using drop-weight impact tester as one of impact test. Absorbed energy of orthotropic composites with using T300 fiber, which are composed of the same fiber and stacking number is higher than that or quasi-isotropic specimen over impact energy 7J, but in case or using T700 fiber, much difference does not show. Also, absorbed energy of orthotropic composites with using T300 fiber, which are composed or stacking number and orientation became more than that of T700 fiber specimen; however great change doesn't show in case of quasi-isotropic specimens. It is found that influence was confirmed between impact energy and absorbed energy as the impact energy is increased with adding the falling weight.

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하이브리드 복합재 철도 차량의 결함검출에 관한 연구 (A Study on the Damage Damage Dection of Woven Cabon/Epoxy Laminates for the Hybrid Composite Train Bodyshell)

  • 이재헌;김정석;엄기영;이동선;정성균
    • 한국복합재료학회:학술대회논문집
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    • 한국복합재료학회 2005년도 추계학술발표대회 논문집
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    • pp.264-267
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    • 2005
  • Impact damages are very important in the perspective of residual strength of composite structures such as aircrafts, ships, and trains because those damages are sometimes not visible on the surface of the point of impact and the impact resistance of laminated composites is usually not so high. Thus, the impact characteristics of laminated composites should he investigated for the safety of composite structures. This paper investigates the low-velocity impact and damage detection conducted on woven carbon/epoxy laminates. Experimental results show that the type of damage is dependent on the impact energy level and the delamination area becomes larger as the impact energy increases.

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다양한 비파괴 측정 방법에 의한 CFRP의 BVID 분석 (Barely Visible Impact Damage Detection Analyses of CFRP by Various NDE Techniques)

  • 임현민;이보영;김영국
    • Composites Research
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    • 제26권3호
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    • pp.195-200
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    • 2013
  • 본 연구에서는 탄소섬유강화플라스틱(CFRP, carbon fiber reinforced plastics)에 충격을 가하여 발생하는 결함에 대한 분석을, 특히 눈으로 식별이 어려운 손상(Barely Visible Impact Damage: BVID)을 중심으로 진행하였다. 낙하형 충격시험기를 통하여 충격 시험을 진행하였고, 추의 자유 낙하를 통하여 실제 항공기에 적용된 복합재료에 충격에 의한 손상을 모사한 후, 표면과 내부에 다양한 비파괴 검사를 적용하여 충격에너지에 따른 시편의 결함 거동을 확인하고 살펴보았다. 이를 위해 여러 가지 비파괴 검사법을 사용하여 결함을 비교, 분석, 검토하였다. 그 결과 눈으로 식별이 어려운 손상과 이를 측정하기 위해 사용된 각각의 측정법에 따른 특성이 논의되었다. 일반적으로 육안으로 보이는 표면결함보다 큰 결함이 내부에 발생하였으나, 충격에너지가 작아지면 내부결함이 표면결함 보다 작을 수 있다는 사실이 관찰되었다.

소음·진동에 의한 가축피해 사례분석 (A Case Study on the Effects of Noise and Vibration on the Damage of Livestock)

  • 박형숙
    • 환경영향평가
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    • 제17권6호
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    • pp.381-391
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    • 2008
  • The instances of the damage to livestock are increasing with frequent environmental disputes on the noise and vibration. This study analyzed 134 open cases dealing with the environmental disputes on livestock damaged by noise and vibration, and being intervened by National Environmental Dispute Resolution Commission. The environmental disputes on the noise and vibration account for 86% of all the disputes, and cases of the consequent damages to livestock have increased. As shown in the 134 cases, pig is the most lethal livestock attacked by the noise and vibration. During last 10 years, 89% of the noise damages hurting the livestock resulted from the noises pertaining to construction and 58% was due to the noise damages from the road constructions. The noise levels in the range of 70~80 dB(A) and the vibration levels of 70~75 dB(V) caused most of the disputes. The average rate of reimbursement for the livestock damages for the last 10 years was higher than the average rate of reimbursement of the total disputes intervened by National Dispute Resolution Commission.