• Title, Summary, Keyword: 압괴 해석

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Energy Absorption of Collision Post Based on North American CFR Regulations for Railway Vehicles (철도차량의 북미 CFR 법규에 대한 충돌 기둥에너지 흡수에 관한 연구)

  • Kim, Seung-Tech;Jeong, Ji-Ho;Choi, Jeong-Yong;Woo, Kwan-Je
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.8
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    • pp.935-943
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    • 2012
  • In accidents involving the collision of railway vehicles, there is a risk that structural members might penetrate the cab frame of the railway vehicle in the space in which the driver or passengers are seated. To reduce this risk, worldwide, studies on the collision of railway vehicles are underway. In North America, the Code of Federal Regulations (CFR) was revised in 2010 to include crush criteria for a collision and the corner post in an end frame. In this study, a crush analysis and crush test for a collision post and a crash analysis for a rigid cylinder were performed according to the CFR. The analysis and test results were compared and reviewed. This study aims to determine the usefulness of crush analysis for developing various end frames, and to understand the crush and crash characteristics and review the accuracy of the analysis.

Energy Absorption Characteristics and Optimal Welding Space of Square Hat Type Thin-walled Tube (정사각 모자형 박판튜브의 에너지흡수특성 및 최적 용접간격)

  • Lee, Hyung-Yil;Kim, Bum-Joon;Han, Byoung-Kee
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.12
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    • pp.2703-2714
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    • 2002
  • In this work, energy absorption characteristics and optimal welding space of spot-welded square hat type tube are investigated via quasi-static crush experiments and finite element (FE) analyses. A FE model reflecting the crush characteristics is established based on the experimentally observed crush mechanisms of specimens with welding spaces (20, 30 & 45 mm) and (25,40 & 55 mm) respectively for two specimen widths (60, 75 mm). The established FE model is then applied to other crush models of widths (50, 60 & 75 mm) with various welding spaces (20, 25, 30, 40, 45, 55, 75, 150, 300 mm) respectively. We examine the energy absorption characteristics with respect to the welding space for each specimen width. The outcome suggests an optimal spot welding space of square hat type thin-walled tube. Energy absorption is also presented in terms of yield strength of base metal, specimen thickness, width, and mean crushing force of spot-welded square hat type thin-walled tube.

Semi Empirical Analysis on the Crushing Mechanism of Thin-Walled Rectangular Tubes (박판 4각튜브의 반실험적 압괴메카니즘 해석)

  • Kim, Cheon-Uk;Han, Byeong-Gi;Im, Chae-Hong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.1
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    • pp.12-21
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    • 1997
  • A model for analysis of the crushing mechanism of thin-walled rectangular tube is presented. The crushing modes of rectangular tubes may be characterized as either compact or noncompact and the model presented only considers compact modes. The unloading process in the crushing are categorized into three different stages where the distinction is based on the ratio of outward to inward fold length. Using the kinematic relations and the energy conservation principle, the instantaneous crush load is derived. An approximate equation that considers the rolling behavior is also given so that the crush load history may be established. The equation is experimentally proved.

On the Dissipation Energy of a Tapered Box Column (경사진 상자형 기둥의 압괴에너지 해석)

  • J.M. Choung;J.W. Lee;S.J. Hong;Y.H. Kim
    • Journal of the Society of Naval Architects of Korea
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    • v.32 no.4
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    • pp.97-104
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    • 1995
  • A study on the structural dissipation energy and crushing strong is presented for the axially compressed straight square box column and off-axially compressed tapered box column. A new formula on the energy dissipation and crushing strength of the tapered box column is proposed, where the tapered box column is replaced by the equivalent straight square box column. It is seen that the theoretical solutions agree well with experimental results.

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Research trends on the automobile crush (자동차 충돌특성 연구동향)

  • 김천욱;한병기;원종진;임채홍
    • Journal of the korean Society of Automotive Engineers
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    • v.18 no.4
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    • pp.1-17
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    • 1996
  • 자동차의 안전에 대한 연구는 객실의 변형제한과 승객의 감속도 축소를 위한 여러가지 구조부재의 에너지 흡수능력 및 흡수 메카니즘을 연구하는데 초점이 맞추어져 왔다. 그 이유는 충돌사고시에 인명을 보호하기 위해서는 차제변형에 의한 물리적 접촉의 회피 뿐 아니라 충돌에너지를 적절히 흡수조절하여 충돌력을 감소시키도록 구조부재를 설계함으로써 충돌안전성이 확보되기 때문이다. 충돌에너지 흡수 특성은 구조부재의 단면 형상과 재질에 따라 달라지며 압괴모드도 구분되어진다. 즉, 복합재료의 압축붕괴특성은 금속이나 플라스틱 재질과는 다르다. 일반적으로 복합재는 재질의 파손으로 에너지가 흡수되지만 금속재는 소성변형으로 에너지를 흡수한다. 이때의 붕괴양상은 작용하중에 따라 축방향 붕괴, 굽힘붕괴, 측면붕괴의 경우는 정규압괴모드(compact mode) 및 불규칙압괴모드(noncompact mode)로 나뉘고, 원통쉘의 경우는 축대칭모드 및 다이아몬드형 모드 등으로 나뉠수 있다. 원형 및 사각 튜브는 광범위한 형상비와 후폭비를 가지도록 제작할 수 있으며 산업전반에 걸쳐 널리 쓰이므로 충돌특성 연구의 대상으로 많은 연구들이 진행되어 왔다. 또한, 충돌특성의 해석을 위한 이론적 모델이 제시되었으며 계속적인 보완이 이루어져 오고 있다.

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Study on Axial Crushing Behaviors of UD Kevlar/Epoxy with Different Trigger Models (트리거 모델에 따른 일방향 케블라/에폭시 복합재 튜브의 축방향 압괴 거동 연구)

  • Kim, Hyung-Uk;Kim, Jung-Seok;Jung, Hyun-Seung;Yoon, Hyuk-Jin;Kwon, Tae-Soo
    • Composites Research
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    • v.23 no.4
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    • pp.28-34
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    • 2010
  • In this paper, in order to develop a realistic trigger model for a unidirectional Kevlar/Epoxy tube, the numerical model has been established and then verified by comparison with the experimental result. To achieve this goal, four different trigger models were candidated and evaluated using the commercial explicit FE code LS-DYNA. In the finite element analysis, the 2D shell element and Chang-Chang failure criterion was used. Mechanical material properties for the model were obtained by material testing in advance. The numerical results were compared with quasi-static test results under axial compressive loading at 10mm/min. The load-crushed displacement curves were very close to the experiments and SEA (specific energy absorption) showed a good agreement with experimental one within less than 5%.

Study on the Axial Crushing Behaviors of UD Kevlar/Epoxy and Carbon-Kevlar/Epoxy Composite Tubes (단방향 케블라/에폭시, 탄소-케블라/에폭시 복합재 튜브의 축방향 압괴 거동에 대한 연구)

  • Kim, Hyung-Uk;Kim, Jung-Seok;Jung, Hyun-Seung;Yoon, Hyuk-Jin;Kwon, Tae-Soo
    • Journal of the Korean Society for Railway
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    • v.13 no.3
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    • pp.271-277
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    • 2010
  • In this paper, a numerical model for a Kevlar/Epoxy and Carbon-Kevlar/Epoxy tube used as an energy absorbing component has been developed and then results have been verified through experiment. The 2D shell element and Chang-Chang failure criterion of LS-DYNA that is commercial explicit FE code was used. Mechanical material properties for the model were obtained by material testing in advance. The numerical results were compared with quasi-static test results under axial compressive loading at 10mm/min. From the results, in the case of the Kevlar/Epoxy tube, load-crushed displacement curves were very close to the experiments and SEA (specific energy absorption) shows a good agreement with experimental one within less than 6%. However, the Carbon-Kevlar/Epoxy tube shows some differences with the experimental results.

FE Simulation of Axial Crushing Test for AZ31 Tube Considering Tension-Compression Asymmetry (압축-인장 비대칭을 고려한 AZ31 튜브의 압괴해석)

  • Yoon, Jong-Hun;Lee, Jung-Hwan
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.9
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    • pp.997-1002
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    • 2012
  • With the increasing demand for lightweight materials to reduce fuel consumption, especially in the transportation industry, magnesium alloys are being widely studied. However, there are several limitations to the large-scale application of magnesium alloys in a structure because of their low formability and strong anisotropy. In order to take into account both the strong anisotropy and tension-compression asymmetry of AZ31 sheet alloy, the Cazacu-Plunkett-Barlat yield criterion (Cazacu, 2006) was adopted in material modeling. The variation of the anisotropic coefficients that describe the yield surface evolution of AZ31 is optimized using an interpolation function based on specific calibration results. It generates continuous yield surfaces, which makes it possible to describe different hardening rates in tension and compression as well as the tension-compression asymmetry of magnesium alloys. The performance of the CPB06 yield criterion for simulating an axial crushing test was tested and compared with that of the Hill (1948) yield criterion.

Equivalent Modeling Technique for 1-D Collision Dynamics Using 3-D Finite Element Analysis of Rollingstock (열차의 3차원 유한요소해석을 이용한 1차원충돌 동역학 등가 모델링 기법)

  • Park, Min-Young;Park, Young-Il;Koo, Jeong-Seo
    • Journal of the Korean Society for Railway
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    • v.13 no.2
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    • pp.139-146
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    • 2010
  • In this study, a new equivalent modeling technique of rollingstock for 1-D collision dynamics was proposed using crash analysis of 3-D finite element model in some detail. To obtain good simulation results of 1-D dynamic model, the force-deformation curves of crushable structures should be well modelled with crash analysis of 3-D finite element model. Up to now, the force-deformation curves of the crushable structures have been extracted from crash analyses of sectionally partitioned parts of the carbody, and integrated into 1-D dynamic model. However, the results of the 1-D model were not satisfactory in terms of crash accelerations. To improve this problem, the force-deformation curves of the crushable structures were extracted from collision analysis of a simplified train consist in this study. A comparative study applying the suggested technique shows in good agreements in simulation results between two models for KHST.

Prediction of Ships' Bow Structural Damage during Collisions (충돌시 선수구조의 손상추정에 관한 연구)

  • P.D.C. Yang
    • Journal of the Society of Naval Architects of Korea
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    • v.29 no.2
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    • pp.92-102
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    • 1992
  • Prediction of energy absorption for bow structure is important for a design of protective structures against collision. For the crushing behaviour of basic element of energy absorption, the plastic mechanism method is applied. The ship's crushing strength of bow section is obtained by summing the energy dissipated in all individual elements. The theoretical predictions are compared with experimental results for ship's bow models published with experimental results for ship's bow models published in the references, and it is observed that the present prediction method of crushing strength correlates well with the experimental results.

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