• Title/Summary/Keyword: Collapse mode

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Collapse of Thin-Walled Hatted Section Tubes (박판 상형 부재의 붕괴 특성연구)

  • Kim, C.W.;Han, B.K.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.2 no.1
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    • pp.65-72
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    • 1994
  • Collapse characteristics of thin-walled hatted section tubes are investigated. The square section members with flanges are substituted by the equivalent rectangular tube. The stiffening effects of flanges are transformed to the restraining plate with the equivalency of buckling strength. The square tubes of single-hatted and double-hatted sections are investigated. The double-hatted section members show symmetric and antisymmetric crushing modes depending on the stiffness of flanges. The single-hatted section members show only symmetric modes. The bifurcation point of the compact crushing modes are investigated by experiments and shown almost same thickness-width ratio of the rectangular tubes. A large maximum crippling strength can be obtained by double-hatted section members with proper flange dimensions.

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A Method for Calculation of Compressive Strength of a One-Sided Stiffened Plate (편면 보강판의 압축강도 해석을 위한 한 방법)

  • C.D. Jang;S.I. Seo
    • Journal of the Society of Naval Architects of Korea
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    • v.28 no.1
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    • pp.117-124
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    • 1991
  • In this paper, a method to overcome inefficiency of the finite element method in the calculation of compressive strength of one-sided stiffened plates, is proposed. In this method the collapse modes of stiffened plates are assumed as follows. a) Overall buckling $\rightarrow$ Overall collapse b) Local buckling $\rightarrow$ Overall collapse c) Local buckling $\rightarrow$ Local collapse In each collapse mode, shape of deflection is assumed, and then elastic large deformation analysis based on the Rayleigh-Ritz method is carried out. One-sided stiffening effect is considered by taking into account of the moment due to eccentricity. Plastic analysis by assuming hinge lines is also carried out. The ultimate strength of a stiffened plate is obtained as the point of intersection of the elastic analysis curve and the plastic one. From this study, it is concluded that the angles between the plastic hinge lines in plastic collapse mode are determined as the ones which give the minimum collapse load, and these angles are different from the ones assumed in the previous studies. Minimum stiffness ratios can also be calculated. Calculated results according to this method show good agreements with the results by the finite element method.

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Effects of high temperatures and hygrothermals on the collapse characteristics of CFRP thin-walled laminates (고온 .senter dot. 고습환경이 CFRP 적층 원통부재의 압궤특성에 미치는 영향)

  • 곽훈이;김정호;양인영
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1995.10a
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    • pp.650-654
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    • 1995
  • In this study, in order to measure energy-absorbing charactistics in collapse test of CFRP thin-walled laminates and interpretate the cause of decreasing age when collapse test is carried out under the environments of high temperatures and hygrothermals, the moisture absorbing behavior according to the variety of orientation angel is observed and collapse characteristics is compared with the influence of high temperatures and hygrothermals. Especially, we supposed to clearly understand reationship between collapse characteristics in proportion to the variety of orientation angel and moisture absorbing. The value of the maximum loading, mean loading,rate of energy absorption energy per unit volume and mass in CFRP thin-walled laminates on the high temperatures and hygrothermals is measured lower than under no moisture absorbing. The maximum collapse loading in dynamic impact test is taken measurement lower than in static collapse test regarding compared with collapse characteristics conformity with the variety of the CFRP circular laminates in high temperatures and hygrothermals. But the absorbed energy per unit mass and volume is almost same and the biggest amount of energy is shown in the CFRP circular laminates with orientation angel of 15 .deg.. Therefore, in the case of use to CFRP circular laminates with axisymmetric mode, CFRP thin-walled structal members with orientation angel of 10 .deg. , 15 . deg. are generally useful.

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Collapse Simulation with a Finite Element Limit Analysis for Thin-walled Structures Considering Forming Effects (성형효과를 고려한 박판 부재의 유한요소 극한해석을 이용한 붕괴거동해석)

  • Kim, Kee-Poong;Heh, Hoon
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.5
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    • pp.182-189
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    • 2002
  • This paper is concerned with a collapse behavior analysis for a thin-walled structure considering farming effects. Numerical simulation is carried out with a finite element limit analysis in order to identify forming effects on collapse behavior of a thin-walled structure such as an S-rail. The formed S-rail contains fabrication histories such as residual stress, work hardening, non-uniform thickness distribution and geometric changes resulted from the forming process. The collapse behavior analysis of an S-rail with forming effects leads to different results from that without such effects. The present study deals with the collapse analysis of the S-rail fabricated with the typical forming, trimming and springback processes. Collapse properties such as the collapse load, the collapse mode and the energy absorption are calculated and investigated In order to identify forming effects. It is fully demonstrated that the design of thin-walled structures needs to consider the forming effects for a proper assessment of the load-carrying capacity and the deformation of the formed structures.

A Study on the Axial Collapse Characteristics of Thin-Walled Members for Vehicles on the Variation of Section Shapes (차체구조용 박육단면부재의 단면형상변화에 따른 축압궤 특성에 관한 연구)

  • 이길성;백경윤;차천석;정진오;양인영
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1549-1552
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    • 2003
  • The front-end side members of automobiles absorb most of the energy in a front-end collision. The front-end side members are required to have a high stiffness together with easiness to collapse sequentially to absorb more impact energy. The axial static collapse test (5mm/mim) was conducted by using UTM with respect to the single hat shaped section members which are the standard section shape of the spot welded section members, to the single cap shaped section members, to the double cap shaped section members and to the double hat shaped section members whose section shape are changed in order to give more stiffness. As a result of test, the energy absorbing characteristic was analyzed for different section shapes. That is, it was analyzed that the change of section shape influenced the absorbing energy, the mean collapse load and the maximum collapse load, and that the relation between the change of section shape and the collapse mode.

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Major causes of failure and recent measurements of tunnel construction (터널시공 중 붕락발생 원인과 최신 보강기술)

  • Park, Bong-Ki;Hwang, Je-Don;Park, Chi-Myeon;Kim, Sang-Su
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.10a
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    • pp.140-153
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    • 2005
  • During the tunnel construction the major failure mode can be categorized as: tunnel failure just after the tunnel excavation without support, failure after application of shotcrete and finally failure after setting the concrete lining. The failure mode just after the tunnel excavation without support, can be further classified as : bench failure, crown failure, face failure, full face failure, failure due to weak strata and failure due to overburden. Moreover the failure after application of shotcrete is classified as heading face failure, settlement of shotcrete support, local failure of shotcrete lining and invert shotcrete. To find out the major causes of tunnel collapse, the investigation was done in case of the second phase of Seoul subway construction. The investigation results depicted that the major causes of tunnel collapse were due to the weak layer of rock/fault and sudden influx of ground water from the tunnel crown. While the investigation results of the mountain road tunnels construction have shown that the major causes of tunnel failure were inadequate analysis of tunnel face mapping results, intersection of faults and limestone cavities. In this paper some recent measurement in order to mitigate such tunnel collapse are presented

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An Experimental Study on the Impact Energy Absorption Mechanism of CFRP/Al Compound Square Tube (CFRP/Al 혼성 사각부재의 충격에너지 흡수 메카니즘의 실험적 고찰)

  • Hwang, Woo Chae;Cha, Cheon Seok;Yang, Yong Jun;Jung, Jong An;Yang, In Young
    • Journal of the Korean Society of Safety
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    • v.30 no.6
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    • pp.12-17
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    • 2015
  • In this study, the collapse characteristic of CFRP/Al compound square tube was investigated experimentally. The conclusions are as follows; The impact collapse characteristic of CFRP/Al compound square tube was found to be the most superior stacking conditions $[90^{\circ}]_8$. It showed that a very stable collapse mode was crushing. In the member with $[0_2{^{\circ}}/90_2{^{\circ}}]_s$ and $[90_2{^{\circ}}/0_2{^{\circ}}]_s$, stacking conditions, $0^{\circ}$ fibers were splayed to the external by laminar bending, while the $90^{\circ}$ fibers were held between the folds of the aluminum member by laminar bending, local buckling and transverse crack. In the member with $[45_2{^{\circ}}/45_2{^{\circ}}]_s$ stacking conditions, fibers were held between the folds of the aluminum member by local buckling and transverse crack.

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.

The Static Collapse Characteristics of CFRP Single and Double Hat Shaped Section Members according to the Interface Number for Lightweight (경량화용 CFRP 단일 모자형 부재와 CFRP 이중 모자형 부재의 계면수 변화에 따른 정적압궤특성)

  • Hwang, Woo-Chae;Cha, Cheon-Seok;Yang, In-Young
    • Journal of the Korean Society of Safety
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    • v.27 no.6
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    • pp.20-25
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    • 2012
  • Currently, the most important purpose in designing automobile is environment-friendly and safety performance aspect. CFRP(Carbon Fiber Reinforced Plastics) of the advanced composite materials as structure materials for vehicles, has a wide application in lightweight structural materials of air planes, ships and automobiles because of high strength and stiffness. In this study, experimental investigations are carried out for CFRP single and double hat shaped section member in order to study the effect of various stacking condition. They were cured by heating to the appropriate curing temperature($130^{\circ}C$) by means of a heater at the vacuum bag of the autoclave. The stacking conditions were selected to investigate the effect of the interface numbers. The CFRP single and double hat shaped section members which manufactured from unidirectional prepreg sheets were made of 8ply. The static collapse tests performed and the collapse mode and energy absorption capability were analyzed according to interface number.