• Journal of the korean Society of Automotive Engineers
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• v.15 no.5
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• pp.22-30
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• 1993

본 연구는 MSC/DYNA EXPLICIT CODE를 이용하여 자동차용 샤시 프레임의 성형성을 파악하기 위한 모델링 방식과 단계별 변형양상, 컴퓨터 시뮬레이션의 결과인 스프링백, 잔류응력, 두께변화, 변형률 등을 소개하기로 한다. 1. 프레임 스탬핑 개요. 2. 해석 모델 및 성형조건. 3. 해석결과 및 고찰.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.2
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• pp.167-175
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• 2014

If volumetric flaws such as bearing pad fretting flaws and debris fretting flaws are detected in the pressure tubes of pressurized heavy water reactors during in-service inspection, the initiation of fatigue cracks and delayed hydrogen cracking from the detected volumetric flaws shall be assessed by using elastic stress concentration factors in accordance with CSA N285.8-05. The CSA N285.8-05 presents only an approximate formula based on linear elastic fracture mechanics for the debris fretting flaw. In this study, an engineering formula considering the geometric characteristics of the debris fretting flaw in detail was derived using two-dimensional finite element analysis and Kinectrics, Inc.'s engineering procedure with slight modifications. Comparing the application results obtained using the derived formula with the three-dimensional finite element analysis results, it is found that the results obtained using the derived formula agree well with the results of the finite element analysis.

• Journal of Korean Society of Steel Construction
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• v.11 no.4 s.41
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• pp.397-407
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• 1999

In this paper, the fatigue safety in the suspension bridge is investigated by using nominal and variable stress, respectively. The technique on structural modeling and the fatigue evaluation using nominal stress are mainly dealt with in this paper. To make the finite element analysis model reflecting the actual structural behavior of the suspension bridge with cross frame, the parametric study is carried out. In this study, the influence of supporting condition. the difference of the results of 2- and 3-D analysis and the number of cross frames modelled in are considered. The nominal stress under the real traffic flow of the bridge is calculated by the combination of the stresses due to the unit DB-24 loading. The nominal stresses for details under consideration are compared with allowable stress ranges specified in the codes and the results are discussed.

• Journal of Korean Society of Steel Construction
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• v.18 no.5
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• pp.515-524
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• 2006

Cross-sectional distortions take place when steel box girders a re subjected to torsional moment, as a consequence of which distortional warping stresses are necessarily developed. Additional normal stresses due to the distortion are should be included at the design stage. The relative magnitude with respect to the maximum bending stress are kept less than the specific values, i.e., at 5~10%, by properly spaced intermediate diaphragms that could prevent the distortional deformation of the box girder. However, current design equations for the stiffness of intermediate diaphragms were derived based on BEF. In this study, the area required by the intermediate diaphragm members are investigated through three-dimensional finite element analyses. The results of the analyses indicate that the current equations give to conservative values for the intermediate diaphragm of box girder bridges. Finally, an improved equation for the area of the intermediate diaphragm is derived from a regression analysis from the finite element analysis results.

• Journal of Korean Society of societal Security
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• v.3 no.1
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• pp.33-42
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• 2010

This study predicts the stress history for truss bridge with local damages by using global-local model combination method. For this end, the global structure is modeled by 3D frame elements and the selected local details are modeled by shell elements. Then superposition principle enable the global-local model to be combined interactively. Because the frame model cannot consider the rigidity of gusset plate and the interation of structural members due to the complexity of stress distribution in truss connection. The section modification factors are proposed to calibrate the stiffness of global frame element. The global-local model combination is verified by comparing the numerical results with experimental data obtained from the proof loading test to the operating truss bridge. Furthermore, stress histrories of the truss bridge are generated in the consideration of the rigidity of truss connection with local damage by using the combination method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.554-561
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• 2016

In this study, loading tests and a strength evaluation of the bogie frame were conducted to verify the structural safety of the bogie system in an intermodal tram, which runs with cars on a road track. The loads were calculated taking into account the features of the road track with many sharp curves and steep gradients, which are different from the track of conventional railway. They were compared with the loads specified in the previous standard specifications. After the comparison, it was confirmed that the loads acting on the bogie system operating on a road track are slightly different from the specified loads. The specified vertical load of the standard specification for all kinds of trains is conservative, but the specified lateral and longitudinal loads are less than the calculated loads. The application of the actual loads was proven to be reasonable in the development of a new railway system. Based on the defined loads, the bogie frame was fabricated on which strain gauges were attached. It was set on the large loading frame so that the stresses could be measured when loads were applied by hydraulic actuators. After measuring the stresses, it was shown that they were below the allowable stress, which verified the structural safety of the bogie frame.

• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.832-835
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• 2011

최근까지 용접구조물의 피로설계는 용접품질 수준에 따라 공칭응력 또는 핫스팟 응력에 의한 S-N선 도로부터 수행하였다. 본 연구에서는 유한요소망의 크기에 덜 민감하면서 기존의 하중모드형식, 두께 효과 및 용접결합형식에 상관없는 등가구조응력(E2S2) 접근법을 이용한 Master S-N선도로부터 철도차량 대차프레임의 피로수명을 평가하고자 한다. 또한 합리적인 철도차량 용접대차프레임의 피로해석 연구일환으로서, 다축피로조건인 EN규격의 피로시험조건하에 이의 피로수명을 평가하고자 한다.

• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.608-610
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• 2011

본 논문에서는 자동차의 도어의 충격봉의 형상에 따른 변형률과 최대응력을 ANSYS Workbench환경을 이용해 원형, 반원형, 모자형 개단면, 정사각형 등의 단면 형상에 따른 변형량 특성을 측정해 본 결과 변형률은 모자형 개단면 모델이 가장 적은 변형률을 가지는 것으로 나왔으며, 무게가 30%정도 적게 나가는 반원형도 두 번째로 적은 변형률을 가지는 것으로 나타났다. 최대응력의 경우는 반원형이 가장 적은 최대응력 값을 가지는 것으로 나왔고, 변형률과는 다르게 중심부 보다는 충격봉과 프레임의 연결부위에서 최대응력이 발생하는 것을 알 수 있었다. 이를 통해서 충격봉의 중심부는 변형률 및 응력이 다른 부분에 비해서 크게 작용하므로, 중앙부위의 단면계수가 높아야 한다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.2
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• pp.176-183
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• 2010

In the steel deck box girder bridges, the deck is composed of deck plate, longitudinal and lateral direction ribs. The bridge, that is considered in this study, has been used for about 40 years and, recently, several cracks were found in the connection area of U-ribs. Further, additional cracks were occurred after some lateral rib plates and longitudinal frames were attached for the purpose of reinforcement. Therefore, the connection method in the U-ribs reinforcement was changed from the bolting to the weldment to get rid of stress concentration and further cracking. In this study, the stress in the U-ribs connection was analysed numerically and variable amplitude stress for the real traffic loads was measured experimentally before and after the frame reinforcement. Finally, the effects of reinforcement method were investigated and discussed.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.5
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• pp.1135-1144
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• 2018

An electric wheelchair used to be utilized as a piece of equipment for the disabled and the elderly in the past, but the recent changes to its functions and forms have made it available across various fields and purposes. In this paper, we propose a continuous track type of electric wheelchair prototype to be used in various fields and environments and a monitoring system to control it. A frame stress design was applied to improve its stability during driving compared with the previous wheelchairs. In addition, we provide a convenience for free and easy operation of them using the App. based on android. A monitoring system based on C# was also added to control a large number of electric wheelchairs. As a result of the implementation and performance evaluation, the von Mises stress value was measured 4.401% within the normal range through five times of stress interpretations, and its accuracy of communication for system manipulation was recorded about 98.75%, which means that it has been proven to be safer than the previous wheelchairs.