• Steel and Composite Structures
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• 제50권2호
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• pp.237-247
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• 2024

Research on interfacial crack formation in orthotropic bi-materials has experienced a notable increase in recent years, driven by growing concerns about structural integrity and reliability. The existence of a crack at the interface of bi-materials has a substantial impact on mechanical strength and can ultimately lead to fracture. The primary objective of this article is to introduce a comprehensive analytical model and establish stress relationships for investigating interfacial crack between two non-identical orthotropic materials with desired crack-fiber angles. In this paper, we present the application of the Interfacial Maximum Tangential Stress (IMTS) criterion, in combination with the Reinforcement Isotropic Solid (RIS) model, to investigate the behavior of interfacial cracks in orthotropic bi-materials under mixed-mode I/II loading conditions. We analytically characterize the stress state at the interfacial crack tip using both Stress Intensity Factors (SIFs) and the T-stress term. Orthotropic materials, due to their anisotropic nature, can exhibit complex crack tip stress fields, making it challenging to predict crack initiation behavior. The secondary objective of this study is to employ the IMTS criterion to predict the crack initiation angle and explore the notable impact of the T-stress term on fracture behavior. Furthermore, we validate the effectiveness of our approach in evaluating Fracture Limit Curves (FLCs) for interfacial cracks in orthotropic bi-materials by comparing our FLCs with relevant experimental data from existing literature.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.560-565
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• 2001

The objective of the present study is to investigate the characteristics for flow and wall shear stress in the aneurysm which is a local dilatation of the blood vessel. The numerical simulation using the commercial software for the laminar and steady flow were carried out over the diameter ratios(ratio of maximum diameter of aneurysm to the diameter of blood vessel) ranging from 1.5 to 2.5 and Reynolds number ranging from 900 to 1800. It was shown that a recirculating vortex occupied the entire bulge with its core located closer to the distal end of the bulge and the strength of vortex increased with increase of the Reynolds number and diameter ratio. Especially, for the Reynolds number of 1800 and diameter ratio of 2.5, the very weak secondary recirculating flow was produced at the left upper of the aneurysm. The position of a maximum wall shear stress was the distal end of the aneurysm(z=18mm) regardless of the Reynolds number and diameter ratios. But the maximum values of the wall shear stress increased in proportion to the increase of Reynolds number and diameter ratio.

• Journal of Advanced Marine Engineering and Technology
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• 제37권6호
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• pp.603-610
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• 2013

유한요소해석을 수행하여 조향장치용 타이로드 볼 조인트의 주름 형상 더스트 커버의 응력과 변형을 평가하였다. 조립상태 및 작동상태 하에서 기존 설계안의 더스트 커버를 해석한 결과, 밀봉성이 우수하고 최대응력은 인장강도보다 낮게 나타났다. 더스트 커버의 최대응력을 저감시키기 위하여 형상설계변수를 선정하고, 다구찌 기법을 사용하여 최적형상을 구하였다. 도출된 최적설계안의 작동상태에서의 최대응력은 초기설계안 대비 22 % 감소되는 것으로 나타났다. 본 연구에서 제시된 방법을 사용하면 더스트 커버의 평가 및 설계를 효율적으로 할 수 있다.

• 한국가스학회지
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• 제16권5호
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• pp.52-57
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• 2012

본 연구에서는 유한요소해석법을 사용하여 다접오링의 밀봉특성에 관련된 변형률, 응력, 접촉법선응력을 해석하였다. 밀봉특성에 관한 FEM 해석결과에 의하면, 다접오링에 작용하는 최대 변형률, 최대압축응력, 최대접촉 법선응력은 기존의 오링에 비해 약 1.7배나 더 높게 나타났다. 이것은 다접오링의 절단면에 U홈을 형성하였기 때문이고, 다접오링은 고압가스 용기, 밸브, 가스기기의 밀봉을 유지하는데 매우 유용할 것으로 판단된다. 그리고, 다접오링에서 가스압력을 높여도 압출파손 현상이 발생되지 않았는데, 이것은 U홈이 있기 때문인 것으로 판단된다. 따라서, 다접오링은 기존의 오링에 비해 밀봉수명을 길게 연장시킬 수 있다.

• 대한기계학회논문집
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• 제7권2호
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• pp.161-167
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• 1983

In this study the phenomenon of cutting stress which arises on cutting tools and work pieces in cutting process is investigated by rake angle of cutting tools and feed for this measurement, P$_{s}$-1 (high modulus, photolastic Inc.) was used as a cutting tool, P$_{s}$-3 (medium modulus, photolastic Inc.) was used as work piece and reduction apparatus was attached to the head stock, and orthogonal cutting was adapted as a cutting method and transparent glass was used to block the strain in the orientation of thickness. The followings are the results of this study. (1) Photoelastic experimental equipments have made it possible to make dynamic measurement and analyze stress distribution in cutting tool and work piece surface which has hitherto been conducted only in static measurement and analyzing method. (2) The maximum stress arising at tools and work pieces in cutting process is on the tool edge tip, and the maximum stress arising on the tip of cutting tools is equal to that on the contacting area of work pieces in values. (3) The distributions of maximum shear stress on certain parts of the cutting tools and work pieces are as follows; for cutting tools, .alpha.=12.deg., .alpha.=0.deg., .alpha.=-12.deg. in order, and for work pieces, .alpha.=-12.deg., .alpha.=0.deg., .alpha.=12.deg. in opposite order.der.

• 한국자동차공학회논문집
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• 제21권6호
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• pp.166-174
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• 2013

This study investigates the strength durability on the results of structural and vibration analysis due to the shape of excavator wheel. As model 2 has the least stress by comparing three models with maximum equivalent stress, model 2 has most durability among three models at static analysis. Maximum equivalent stress is shown at the bottom part contacted with ground and this part on wheel is most affected by load in cases of all models. Safety factor can be decided with the value of 2.3 by considering the yield stress of this model. The range of maximum harmonic response frequencies becomes 6900 to 7000Hz. As model 2 has the least total deformation and equivalent stress at these critical frequencies, model 2 has the most durability at vibration analysis among three models. The structural and vibration analysis results in this study can be effectively utilized with the design of excavator wheel by investigating prevention and durability against its damage.

• Nuclear Engineering and Technology
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• 제52권4호
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• pp.802-810
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• 2020

Three-dimensional finite element simulations are implemented for the in-pile thermo-mechanical behavior in U-Mo/Al monolithic fuel plates with different thermal creep rates of cladding involved. The numerical results indicate that the thickness increment of fuel foil rises with the thermal creep coefficient of cladding. The maximum Mises stress of cladding is reduced by ~85% from 344 MPa on the 98.0^th day when the creep coefficient of cladding increases from 0.01 to 10.0, due to its equivalent thermal creep strain enlarged by 3.5 times. When the thermal creep coefficient of Aluminum cladding increases from 0 to 1.0, the maximum mesoscale stress of fuel foil varies slightly. At the same time, the peak mesoscale normal stress of fuel foil can reach 51 MPa on the 98.0^th day for the thermal creep coefficient of 10, which increases by 60.3% of that with the thermal creep un-occurred in the cladding. The maximum through-thickness creep strain components of fuel foil differ slightly for different thermal creep coefficients of cladding. The dangerous region of fuel foil becomes much closer to the heavily irradiated side when the creep coefficient of cladding becomes 10.0. The creep performance of Aluminum cladding should be optimized for the integrity of monolithic fuel plates.

• 비파괴검사학회지
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• 제22권5호
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• pp.539-544
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• 2002

기계구조물의 피로과정에 대한 손상정도를 평가하기 위하여 X선 회절을 이용하여 반가폭 및 하중방향과 수직방향에서의 2축에 대한 잔류응력의 변화를 측정하였다. 반가폭은 피로과정의 초기에는 큰 변화를 보이지만 피로수명 비의 약 $10{\sim}20%$ 이후에는 큰 변화를 보이지 않았다. 2축 방향에 대한 잔류응력은 피로수명비의 40% 전후에서 길이방향의 경우는 감소와 증가를, 폭방향의 경우는 증가와 감소를 하였으며, 응력진폭이 클수록 잔류응력의 절대 값은 커지는 증가하는 경향을 나타내었다.

• 대한기계학회논문집B
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• 제27권7호
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• pp.920-928
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• 2003

The objective of the present study was to investigate the characteristics of flow and wall shear stress under steady and pulsatile flow in the aneurysm. The numerical simulation using the software were carried out for the diameter ratios ranging from 1.5 to 3.0, Reynolds number ranging from 900 to 1800 and Womersley number, 15.47. For steady flow, it was shown that a recirculating vortex occupied the entire bulge with its core located closer to the distal end of the bulge and the strength of vortex increased with increase of the Reynolds number and diameter ratio. The position of a maximum wall shear stress was the distal end of the aneurysm regardless of the Reynolds number and diameter ratios. For the pulsatile flow, a recirculating flow at the bulge was developed and disappeared for one period and the strength of vortex increased with the diameter ratio. The maximum values of the wall shear stress increased in proportion to the diameter ratio. However, the position of a maximum wall shear stress was the distal end of the aneurysm regardless of the diameter ratios.

• 한국생산제조학회지
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• 제21권3호
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• pp.451-458
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• 2012

This study aims at the structural analysis with fatigue according to the configuration of railway vehicle wheel. Maximum equivalent stress or deformation is shown at the lower face in contact with wheel and rail. As model B has the maximum stress or deformation which becomes lower than model A, model B is shown to have more durability than model A. Among the cases of nonuniform fatigue loads, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. In case of 'Sample history' with the average stress of 0 to $-10^{11}$ Pa and the amplitude stress of 0 to $10^{10}$ Pa, the possibility of maximum damage becomes 3%. This stress state can be shown with 6 times more than the damage possibility of 'SAE Bracket history' or 'SAE transmission'. The structural result of this study can be effectively utilized with the design of railway vehicle wheel by prevention and durability against its damage.