• Title/Summary/Keyword: 좌굴모우드

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Dynamic Stability of Orthotropic Cylindrical Shells under Axial Compression (압축하중을 받는 직교이방성 원통셸의 동적 안정성)

  • Kim, C. W.;;Sung Y. Lu
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.7 no.1
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    • pp.73-82
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    • 1983
  • 초기결함을 가진 직교이방성원통셸이 축방향스텝하중을 받은 때의 동적좌굴을 연구하였다. 원통 쉘의 운동방정식은 비선형 Donnell 방정식을 사용하였으며 변위식에는 6개항을 채용하였다. 좌굴 조건은 원통셸의 수직변위와 길이변화의 급격한 변화로써 정의하였다. 좌굴모우드형상은 초기결 함과 쉘재료의 이방성에 따라 달라짐은 발견하였고 좌굴강도는 초기결함의 증가에 따라 크게 감 소된다.

Tests on Failure of Steel Angles due to Very Low-Cycle Fatigue of Loading (극저사이클 재하하에서 앵글 강부재의 파괴실험)

  • Park, Yeon Soo;Kim, Sung Chil;Lim, Jung Soon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.12 no.4_1
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    • pp.23-32
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    • 1992
  • The objective of this study is to identify the quantitative relationships among the important physical factors associated with failure of steel members under strong seismic excitations through very low-cycle fatigue tests. Very low-cycle fatigue is meant to be structural fatigue causing cracks and rupture in about 5~30 cycle ranges. The angle specimen was subjected to repeated axial Ioad after undergoing inelastic buckling. The test results reveal that the energy absorption capacities vary heavily with the history of loading and the failure mode. The maximum values of residual local strain at the initiation of a visible crack due to the very low-cycle fatigue were of the order of 25~40%, regardless of loading patterns, deflection modes, and width-to-thickness ratios.

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Crashworthiness Design Concepts for the Improved Energy Absorbing Performance of an Aluminum Lightweight Vehicle Body (알루미늄 경량 차체의 충돌에너지 흡수 성능 향상을 위한 설계 개선 연구)

  • 김범진;허승진
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.3
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    • pp.155-160
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    • 2003
  • For the weight reduction of vehicle body up to 20∼30% compared to the conventional monocoque steel body·.in-white, most automotive manufacturers have attempted to develop the aluminum intensive body-in-white using an aluminum space frame. In this paper, the crush tests and simulations for the aluminum extrusions filled with the structural from are performed to evaluate the collapse characteristics of that light weighted material. From these studies. the effectiveness of structural for is evaluated in improving automotive crashworthiness. In order to improve the improve energy absorption capability of the aluminum space frame body, safety design modifications are performed and analyzed based on the suggested collapse initiator concepts and on the application of the aluminum extrusions filled with structural foam. The effectiveness of these design concepts on the frontal and side impact characteristics of the aluminum intensive vehicle structure is investigated and summarized.

Buckling Behavior and Variation of Dynamic Characteristics under Shear Displacement of Cylindrical Shell (원통쉘의 좌굴 거동 및 전단 변위에 따른 동적 특성 변화)

  • 이창훈;우호길;구경회;이재한
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.756-759
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    • 2001
  • The purpose of this paper is to investigate the buckling and dynamic characteristics for the cylindrical shell under shear loading. To do this, a vibration model tests and analyses and static buckling analyses were performed for the reduced scale model of nuclear reactor vessel. From the results of vibration modal analysis with the pre-shear displacement loads, it is known that the beam vibration mode is not affected by the shear displacement, however shell vibration modes are significantly affected by it. As the pre-shear displacement increases to the critical buckling displacement, the 1st shell vibration frequency in greatly reduces and approaches to zero value.

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Test and Analysis for Axial and Bending Collapse Characteristics Evaluation of Aluminum Extruded Beams (알루미늄 압출재의 압괴 및 굽힘붕괴 특성규명을 위한 시험 및 해석)

  • 김범진;허승진;구정서;송달호
    • Journal of the Korean Society for Railway
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    • v.4 no.3
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    • pp.110-115
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    • 2001
  • Recently, many engineers actively participate in research and development w.r.t the weight reduction and the safety increase of vehicle body structure to meet the requirement of fuel economy and regulations. However, vehicle design concept related with weight reduction and safety increase is reduced to the design conflict problem. In the paper, the axial and bending collapse test of aluminum extruded beams are performed and the collapse characteristics are investigated. The analysis method to verify the fracture characteristics of aluminum extruded beam is presented and discussed.

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Design of the Impact Energy Absorbing Members and Evaluation of the Crashworthiness for Aluminum Intensive Vehicle (알루미늄 초경량 차체의 충격 흡수부재 설계 및 충돌 안전도 평가)

  • Kim, Heon-Young;Kim, Jin-Kook;Heo, Seung-Jin;Kang, Hyuk
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.1
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    • pp.216-233
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    • 2002
  • Due to the environmental problems of fuel consumption and vehicle emission, etc., automotive makers are trying to reduce the weight of vehicles. The most effective way to reduce a vehicle weight is to use lighter materials, such as aluminum and plastics. Aluminum Intensive Vehicle(AIV) has many advantages in the aspects of weight reduction, body stiffness and model change. So, most of automotive manufacturers are attempting to develop AIV using Aluminum Space Frame(ASF). The weight of AIV can be generally reduced to about 30% than that of conventional steel vehicle without the loss of impact energy absorbing capability. And the body stiffness of AIV is higher than that of conventional steel monocoque body. In this study, Aluminum Intensive Vehicle is developed and analyzed on the basis of steel monocoque body. The energy absorbing characteristics of aluminum extrusion components are investigated from the test and simulation results. The crush and crash characteristics of AIV based on the FMVSS 208 regulations are evaluated in comparison with steel monocoque. Using these results, the design concepts of the effective energy absorbing members and the design guide line to improve crashworthiness for AIV are suggested.

Free Vibration Analysis of Laminated Composite Stiffened Plates under the In-plane Compression and Shear Loads (면내 압축 및 전단하중을 받는 적층 복합 보강 판의 자유진동해석)

  • Han, Sung-Cheon;Choi, Samuel
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.1A
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    • pp.191-203
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    • 2006
  • The vibration characteristics of composite stiffened laminated plates with stiffener is presented using the assumed natural strain 9-node shell element. To compare with previous research, the stiffened plates are composed of carbon-epoxy composite laminate with a symmetric stacking sequence. Also, the result of the present shell model for the stiffener made of composite material is compared with that of the beam model. In the case of torsionally weak stiffener, a local buckling occurs in the stiffener. In this case, the stiffener should be idealized by using the shell elements. The current investigation concentrates upon the vibration analysis of rectangular stiffened and unstiffened composite plates when subjected to the in-plane compression and shear loads. The in-plane compression affect the natural frequencies and mode shapes of the stiffened laminated composite plates and the increase in magnitude of the in-plane compressive load reduces the natural frequencies, which will become zero when the in-plane load is equal to the critical buckling load of the plate. The natural frequencies of composite stiffened plates with shear loads exhibit the higher values than the case of without shear loads. Also, the intersection, between the curves of frequencies against in-plane loads, interchanges the sequence of some of the mode shapes as a result of the increase in the inplane compressive load. The results are compared with those available in the literature and this result shows that the present shell model for the stiffened plate gives more accurate results. Therefore, the magnitude, direction type of the in-plane shear and compressive loads in laminated composite stiffened plates should be selected properly to control the specific frequency and mode shape. The Lanczos method is employed to solve the eigenvalue problems.

A Study on Characteristics of Damageability and Repairability with Similar Platform Type at Low Speed 40% Offset Crash Test (동일 플렛폼 차량에 대한 저속 충돌시 손상성 수리성에 미치는 영향에 관한 연구)

  • Lim, Jong-Hun;Park, In-Song;Heo, Seung-Jin
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.2
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    • pp.108-113
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    • 2005
  • The damageability and repairability of similar platform type vehicles could be very concerned with design optimization. In all the vehicles crash tested, small size passenger vehicles were weakness in aspect of damageability and repairability. The most critical area appears to be repair cost considering that parts cost is the largest portion of total repair cost segments. Besides repair cost, attaching method of front sidemember and subframe are placed special importance for impact energy absorption and damageability and repairability. So in order to improve damageability and repairability of vehicle structure and body component of the monocoque type passenger vehicles, the end of front side member and front back beam should be designed with optimum level and to supply the end of front side member as a partial condition approx 300mm. The effectiveness of design concept on the 40% offset frontal impact characteristics of the passenger vehicle structure is investigated and summarized.