• Title, Summary, Keyword: 저속 충격하중

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항공기 복합재 구조물의 저속충격 해석방법 분석

  • Choi, Ik-Hyeon
    • Aerospace Engineering and Technology
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    • v.2 no.1
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    • pp.213-222
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    • 2003
  • Some analytical methods to analyze low-velocity impact force history of composite laminated structures used in aerospace vehicles are reviewed. A classical method used at initial research of low-velocity impact problem in 1980s was reviewed on its physical meaning, and the approximate method assuming the shape of impact force history as a sinusoidal wave was reviewed. A parametric study on contact constant and exponent in contact law was performed in order to analyze an effect on impact force history, and finally its was understood that impact force history could be analyzed accurately even though the linearized contact law was used. Also, in this paper it was shown that impact problem could be analyzed simply and easily using a commercial finite element code.

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Low-Velocity Impact Response and Damage Analysis of Composite Laminates Under Initial In-plane Loading (초기 면내하중을 받는 복합적층판의 저속충격거동 및 손상해석)

  • Choi, Ik-Hyeon
    • Composites Research
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    • v.22 no.1
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    • pp.1-8
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    • 2009
  • In this paper low-velocity impact response and damage of composite laminates is analytically investigated. A modified displacement field of plate considering initially loaded in-plane strain is proposed. From the displacement field a finite element equation on structural behavior of composite laminate is newly induced and a computational program is coded. Numerical results using the FEM code is compared with the numerical ones from reference. Additional numerical analysis is performed on another impact condition and effect of initial in-plane load is reviewed. Potential delamination damage area in the first inter-ply surface from bottom of laminate is approximated and effect of initial in-plane load and impact condition is also reviewed.

Analysis of Behaviors of Concrete Strengthened with FRP Sheets and Steel Fibers Under Low-Velocity Impact Loading (저속 충격하중에서의 FRP Sheet 및 강섬유 보강 콘크리트의 거동 해석)

  • Lee, Jin Young;Kim, Mi Hye;Min, Kyung Hwan;Yoon, Young Soo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.15 no.4
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    • pp.155-164
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    • 2011
  • In the case of impact loading test, measurement of the test data has difficulties due to fast loading velocity. In addition, the dynamic behaviors of specimens are distorted by ignoring local fracture. In this study, therefore, finite element analysis which considers local fracture and strain rate effect on impact load was performed by using LS-DYNA, an explicit analysis program. The one-way and two-way specimens strengthened with FRP Sheets and steel fibers were considered as analysis models. The results showed that the impact resistance of steel fiber reinforced concrete (SFRC) and ultra high performance concrete (UHPC) was enhanced. In the case of specimens strengthened with FRP Sheets, GFRP was superior to CFRP in the performance of impact resistance, and there was little effect of the FRP Sheet orientation. The reliability of this analysis model was verified by comparing with previous experimental results.

Evaluation of Residual Strength of CFRP Pressure Vessel After Low Velocity Impact (저속 충격 하중을 받은 탄소섬유강화 복합재 압력용기의 잔류강도 저하 평가)

  • Park, Jae-Beom;Kim, Dong-Ryun;Kim, Hyung-Geun;Hwang, Tae-Kyung
    • Composites Research
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    • v.21 no.3
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    • pp.9-17
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    • 2008
  • In this paper, the low velocity impact characteristics of filament winding CFRP pressure vessel was investigated using numerical and experimental methods. The cylinder part of CFRP vessel was impacted using triangular shape impactor which simulated the sharp edge of dropping tools and impact response behavior of CFRP was reviewed. The mechanical behavior, such as deformation and stress distribution, were also predicted by explicit finite element method and the validity of the model was investigated. For the quantitative evaluation of the residual strength of the pressure vessel after impact, a series of the ring specimens was cut from the impacted vessel and its burst pressure was measured by hydraulic pressure hoop tension test. As the results, the relationship between the residual strength degradation and the impact energy was successively obtained and a useful methodology to evaluate quantitatively the impact damage tolerance of CFRP pressure vessel was established.

Nonlinear Analysis of Composite Laminates Subjected to Low-Velocity Impact (복합적층판의 저속충격 거동에 대한 비선형 해석)

  • Choi, Ik-Hyeon;Hong, Chang-Sun;Lee, In
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.3
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    • pp.757-770
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    • 1991
  • 본 연구에서는 조속충격을 받는 복합적층판의 거동에 대해 횡전단변형과 대처 짐효과를 동시에 고려하여 선형해석한 결과와의 차이를 비교, 검토하여 저속충격무제 의 해석에 있어서 비선형해석의 중요성을 보이는데 있다.그리고 충격체의 질량과 속도가 충격하중과 판의 거동, 그리고 동적 변형도등에 미치는 영향을 파악하여 복합 적층판의 외부 물체에 의한 저속충격문제를 이해 하고자 한다.

Analysis of Low Velocity Impact on Biomimetic Composites Mimicking Nacre (진주조개를 모방한 생체모방 복합재료의 저속충격 해석)

  • Jo, Seung-Un;Beom, Hyeon-Gyu
    • Composites Research
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    • v.23 no.4
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    • pp.1-6
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    • 2010
  • The dynamicresponse of biomimetic composites mimicking nacre under low velocity impact is investigated. The composites have hierarchical structures with a staggered pattern consisting of a protein and a mineral. To analyze the impact response of the composites, the finite element method is used. The effects of the hierarchical structures of the compositeson the dynamic response are examined. It is shown that the maximum stress, displacement and contact force in the composite subjected to low velocity impact decrease as the level of structural hierarchy increases.

Low Velocity Impact Behavior of Aluminium and Glass-Fiber Honeycomb Structure (알루미늄과 유리섬유 하니컴 구조의 저속 충격 거동)

  • Kim, Jin Woo;Won, Cheon;Lee, Dong Woo;Kim, Byung Sun;Bae, Sung In;Song, Jung Il
    • Composites Research
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    • v.26 no.2
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    • pp.116-122
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    • 2013
  • In this study, impact behavior of aluminium and glass-fiber structure is studied under low impact velocity. Compression test is carried out to investigate the compressive strength of the specimens. The degree of damage is observed using microscopy and compared with the experimental analysis data. The maximum load capacity, impact strength and elastic energy of glass-fiber honeycomb sandwich panel are more than the aluminium honeycomb sandwich panel.

Low Velocity Impact Monitoring for a Composite Sandwich Beam Using Piezo Thin Film Sensors (압전필름센서를 이용한 복합재 샌드위치 보의 저속충격 모니터링)

  • Park, Chan Ik;Lee, Gwan Ho;Kim, In Geol;Lee, Yeong Sin
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.31 no.2
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    • pp.51-56
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    • 2003
  • The piezoelectric thin film(PVDF: polyvinylidene fluoride) sensors having good dynamic sensing charachteristics can be used to monitor low vwlocit impact on composite structures. The impact response function for composite sandwich beam was derved. The impact tests at low energy without inducing damage were performed on the instrumented drop weight impact tester. The measured signals of PVDF sensors attached on the surface of the beam agreed well with the simulated signals. And the inverse technique was applied to reconstruct the impact forces from the PVDF sensor signals. Most of reconstructed impact forces showed good agreement with the measured forces. The comparison results showed that the piezoelectric thin film sensor can be used to monitor the low velocity impact on composite sandwich structures.

Punching Behavior of Concrete Strengthening with CFRP Sheet under Low Velocity Impact Loading (CFRP Sheet로 보강한 콘크리트의 저속 충격하중에 하에서의 펀칭파괴 거동)

  • Min, Kyung-Hwan;Cho, Seong-Hun;Ahn, Mi-Young;Lee, Jin-Young;Yoon, Young-Soo
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.9-10
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    • 2010
  • In this study, the static and low velocity impact tests for two-way concrete specimens strengthening with the CFRP sheets were carried out. The specimens that had a dimension of $50{\times}350{\times}350mm$ with 40 MPa plain concrete and steel fiber reinforced concrete which had same mixture to plain concrete and 0.75% steel fibers were fabricated. The specimens reinforced with the CFRP or steel fibers showed mixed failure modes, splitting and punching, also splitting cracks and fragments were much reduced than plain concrete specimens'. Two-way concrete members reinforced with the CFRP and steel fiber simultaneously dissipated 6.8 times larger energy than not-retrofitted members' under the low-velocity impact loading.

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Analysis of low-velocity impact on composite sandwich panels using an assumed strain solid element (가정변형률 솔리드 요소를 이용한 복합재 샌드위치 평판의 저속충격 해석)

  • Park, Jung;Park, Hoon-Cheol;Yoon, Kwang-Joon;Goo, Nam-Seo;Lee, Jae-Hwa
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.30 no.7
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    • pp.44-50
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    • 2002
  • Low-velocity impact on composite sandwich panel has been investigated. Contact force is computed from a proposed modified Hertzian contact law. The Hertzian contact law is constructed by adjusting numerical value of the exponent and reducing the through-the- thickness elastic constant of honeycomb core. The equivalent transverse elastic constant is calculated from the rule of mixture. Nonlinear equation to calculate the contact force is solved by the Newton-Raphson method and time integration is done by the Newmark-beta method. A finite element program for the low-velocity impact analysis is coded by implementing these techniques and an 18-node assumed strain solid element. Behaviors of composite sandwich panels subjected to low-velocity impact are analyzed for various cases with different geometry and lay-ups. It has been found that the present code with the proposed contact law can predict measured contact forces and contact times for most cases within reasonable error bounds.