• Journal of the Korea Concrete Institute
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• v.19 no.4
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• pp.449-456
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• 2007

This research was conducted to analyze the features of the critical tensile stresses at the top and bottom of the concrete slab in the jointed concrete pavement (JCP) when subjected to both the environmental and vehicle loads. First, the stress distribution in JCP was analyzed when the system was subjected to only the environmental loads or the vehicle loads by using the finite element model of JCP. Then, the stresses were analyzed when the system was subjected to the environmental and vehicle loads at the same time. From this study, it was found that the critical tensile stresses at the slab bottom under the vehicle loads were almost constant regardless of the loading positions once the loads were applied at the positions having some distance from the transverse joint. The critical tensile stresses at the slab bottom could be obtained using the model consisting of normal springs for underlying layers by adding the critical stresses due to the environmental loads and the vehicle loads for the curled-down slab, and by subtracting the critical stress due to the environmental loads from that due to the vehicle loads for the curled-up slab. The critical tensile stresses at the top of the slab could be obtained using the model consisting of tensionless springs for underlying layers by adding the critical stress due to the environmental loads and the stress at the middle of the slab under the vehicle loads applied at the joint for the curled-up slab. An alternative to obtain the critical stresses at the top of the slab for the curled-up slab was to use the critical stresses under only the environmental loads obtained from the model having normal springs for underlying layers.

• International Journal of Highway Engineering
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• v.8 no.3 s.29
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• pp.143-153
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• 2006

The differences in the stress distribution and the critical stresses in concrete pavement systems were analyzed when the dual-wheel single-, tandem-, and tridem-axle loads were applied at the interior and the edge of the pavement. The effects of the concrete elastic modulus, slab thickness, foundation stiffness, and tire contact pressure were investigated. The stresses under the interior loads were calculated using the transformed field domain analysis and stresses under the edge loads were obtained using the finite element method. The critical stresses under the interior and the edge loads were compared with respect to various parameters and the equations to predict the ratio between the stresses under the edge and the interior loads were developed and verified. From this study, it was found that the trends of the changes in the critical concrete stresses under the interior and the edge loads were very similar and the critical stress locations under those loads were identical. The critical stress ratio, which was obtained by dividing the critical stress under the edge loads into that under the interior loads, decreased with increasing the number of axles. That ratio became larger as the concrete elastic modulus increased, the slab thickness increased, the foundation stiffness decreased, and the tire contact pressure increased.

• 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.

• International Journal of Highway Engineering
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• v.8 no.4 s.30
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• pp.13-24
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• 2006

The stresses in concrete pavement systems are larger when vehicle loads are applied at pavement edges, and these large stresses significantly affect the behavior and performance of pavements. Therefore, in this study, the stress distribution and the critical stresses in concrete pavements were investigated using a finite element model when dual-wheel single-, tandem-, and tridem-axle loads were applied at pavement edges. First, the stress distribution along the longitudinal and transverse directions was analyzed, and then the effects of slab thickness, concrete elastic modulus, and foundation stiffness on the stress distribution were investigated. The effect of the tire contact pressure related to the tire print area was also studied. The location of the critical stress occurrence in concrete pavements was finally investigated. From this study, it was found that the critical concrete stress due to edge loads became larger as the concrete elastic modulus increased, the slab thickness increased, and the foundation stiffness decreased. The effect of the tire contact pressure on the critical stress was clear as the slab thickness became smaller. The critical stress location in the transverse direction was independent of the concrete elastic modulus and the foundation stiffness; however, it moved into the interior as the slab thickness increased. The critical stress location in the longitudinal direction was under the axle for single- and tandem-axle loads, but for tridem-axle loads, it tended to move under the middle axle from the outer axles as the concrete elastic modulus and/or slab thickness increased and the foundation stiffness decreased.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.579-582
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• 2011

본 논문에서는 9 % Ni강 LNG 저장탱크 조사를 통해서 유한요소해석을 수행하여 구조건전성을 평가하였으며 실용에서 활용할 수 있는 자료를 제시하였다. 과거의 LNG 저장탱크의 설계는 2차원 선에서만 유한요소해석이 수행되었으나 보다 진보된 하드웨어와 소프트웨어의 발전으로 3차원 유한요소해석이 가능케 되었다. 본 연구에서는 9 % Ni 강 LNG 저장탱크 내조의 정적 구조 해석이 상용 유한 요소 해석 프로그램인 ABAQUS를 통해 수행되었다. LNG 저장 탱크 내조 시공 시 용접부 형상을 참고하여 용접부 모델을 고려한 해석을 각각 수행하였다. 용접부의 탄성계수의 변화를 통하여 최대응력과 최대변위를 계산하였다. 실제 LNG tank의 운용 시 발생하는 하중은 자중과, 수두 압과, 온도차에 의한 열응력이며 이들이 복합적으로 작용하였을 시, 용접선을 고려하지 않은 모델에 대해서는 최대응력이 207 MPa이며, 동일 조건에서 용접선을 포함한 모델에 대해 해석을 수행한 결과로서 최대응력이 그보다 약 100 MPa 정도 상승한 결과가 나타났다. 하중조건에서 온도차에 의한 열응력을 고려함과 고려하지 않음을 비교함으로서 실제 열응력에 대해서는 내조에 큰 영향을 미치지 않음을 확인하였다.

• Explosives and Blasting
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• v.30 no.1
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• pp.1-8
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• 2012

In this study, the inner principal stress of concrete blocks caused by an impact load was analyzed with a finite element program, Visual FEA, which was used to model the cross section of the concrete blocks. As a result, it was found that the deviation of the maximum principal stress was varied 2 to 3 times depending on the physical properties of the concrete blocks.

• Journal of the Korea Concrete Institute
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• v.18 no.5 s.95
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• pp.695-702
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• 2006

The stress distribution and the critical stresses in concrete pavements were analyzed using formulations in the transformed field domains when dual-wheel single-, tandem-, and tridem-axle loads were applied. First the accuracy of the transformed field domain analysis results was verified by comparing with the finite element analysis results. Then, the stress distribution along the longitudinal and transverse directions was investigated, and the effects of slab thickness, concrete elastic modulus, and foundation stiffness on the stress distribution were studied. The effect of the tire contact pressure related to the tire print area was also studied, and the location of the critical stress occurrence in concrete pavements was finally investigated. From this study, it was found that the critical concrete stress due to multi-axle loads became larger as the concrete elastic modulus increased, the slab thickness increased, and the foundation stiffness decreased. The number of axles did not tend to affect the critical stress ratio except for a small foundation stiffness value with which the critical stress ratio became significantly larger as the number of axles increased. The critical stress location in the transverse direction tended to move into the interior as the tire contact pressure increased, the concrete elastic modulus increased, the slab thickness increased, and the foundation stiffness decreased. The critical stress location in the longitudinal direction was under the axle for single- and tandem-axle loads, but for tridem-axle loads, it tended to move under the middle axle from the outer axles as the concrete elastic modulus and/or slab thickness increased and the foundation stiffness decreased.

• Korean Journal of Materials Research
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• v.5 no.4
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• pp.468-475
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• 1995

활성금속 브레이징 방법으로 스테인레스 스틸과 질화규소를 접합하여 기계적 특성 및 유한요소법을 사용하여 접합체에서 발생되는 잔류응력의 크기를 조사하였다. 고강도 접합체를 제조하기 위하여 연성금속인 Cu 및 Cu/Mo 적층체를 중간재로 사용하였으며, 중간재의 두께 및 구조에 따라 접합체에서 발생되는 잔류응력의 크기 및 분포가 접합강도에 미치는 영향에 관하여 조사하였다.중간재인 Cu의 두께가 0.2mm 일대 세라믹스에 발생되는 최대 잔류응력의 크기가 급격히 감소하였으며, 최대 접합강도가 나타났다. Cu/Mo 다층 중간재를 사용한 접합체에서는 Cu/Mo 두께비가 감소할수록 접합강도는 증가되었다. 스테인레스 스틸/질화규소 접합체에서 Cu/Mo 중간재의 사용은 Cu 중간재 사용보다 접합강도를 증가시키는데 효과적이었으며, 최대 접합강도는 450Mpa 정도이었다. Cu/Mo 중간재를 사용한 접합체에서는 Mo에 최대 인장방향의 잔류응력이 발생하여 강도 측정시 Mo의 지배적인 소성변형으로 잔류응력이 감소되어 접합체의 접합강도를 향상시키는 것으로 생각된다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.10
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• pp.1297-1303
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• 2013

A nonlinear finite element analysis is performed to evaluate the sealing capability and stress of dust covers for the ball joint of an automotive steering system. The analysis is performed for two types of dust covers: wrinkle type and pot type. The assembly condition and operation condition are analyzed, and the maximum stress and contact normal stress at the ribs are evaluated. It is confirmed that the sealing capability of both types is fairly good, but the wrinkle type is better than the pot type in terms of the maximum stress.

• Journal of Welding and Joining
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• v.15 no.3
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• pp.12-20
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• 1997

구조의 용접접합부에는 재료의 항복응력 크기의 용접잔류응력이 발생되고, 이 잔류응력 상태에서는 응력비(최소응력/최대응력)의 영향이 거의 없다는 것이 일정 진폭 하중조건의 피로실험결과로부터 알려져 있다. 이와 관련하여, 용접구조의 설계 단계에서는 초기 용접잔류응력이 그래도 잔류한 소형실험편의 일정진폭하중 상태의 피로실험 결과로부터 도출된 피로설계선도(S-N 선도)를 이용, 변동하중에 의한 응력 진폭의 밀도분포만으로 일생동안의 누적피해도를 구해 피로강도를 평가하는 것이 일 반적이다. 지금까지는 선박용접구조의 경우도 이러한 개념으로 피로강도 평가를 수행 하였으나, 일반적인 육상 또는 해상 용접구조물과는 달리, 화물의 적재 등의 정하중 이력에 의한 응력변동폭은 피로를 유발하는 파랑 응력변동폭보다 상당히 크다. 그리 고, 정하중에 의해 용접접합부에 인장응력을 발생시키는 하중이력을 받을 경우, 초기 용접잔류 응력은 상당히 저하될 것으로 생각된다. 본 연구에서는 인장응력을 유발하는 정하중 이력에 의해 저하된 용접잔류응력분포와 이러한 잔류응력분포를 가진 선측 종늑골 용접접합부의 피로강도를 검토한다.