• 한국기계가공학회지
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• 제6권2호
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• pp.3-8
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• 2007

Nonlinear property and contact matter are analyzed about the pipe applied with internal pressure through this study. The weakest part and its safety can be examined. Maximum equivalent stress is shown at the contact surface between bolt and nut. The value of contact stress with the pressure of 12MPa is increased 1.4 times as large as that with no pressure. The maximum contact pressure is shown at the clamp corner of the external surface on pipe. The value of contact pressure with the pressure of 12MPa is increased 1.4 times as large as that with no pressure. The radial deformation with no pressure is also increased greatly at the middle part of internal surface on pipe. But this maximum deformation on pipe with the pressure of 12MPa is shown at the part far away the support of pipe. This value is increased 5.7 times as large as that value with no pressure. As contact status, the sticking occurs most at the external surface of pipe. It also tends to occur at the contact surface between bolt and nut. At the external surface of pipe, the sticking in case of the pressure of 12MPa occurs more than that in case of no pressure.

• 한국가스학회지
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• 제21권4호
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• pp.70-75
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• 2017

본 연구에서는 차단기능형 수평식 가스밸브와 기존 수직식 가스밸브의 변형거동 안전성을 FEM으로 해석하였다. FEM 해석결과에 의하면, 차단기능형 수평식 가스밸브의 나사부와 가스방출구에 가스내압이 작용할 때 밸브몸체의 우측 끝단부에서 최대 변형량 $4.4{\mu}m$가 발생하였다. 두 번째로 큰 변형량 $2.9{\mu}m$는 안전밸브가 설치된 포트의 끝단부에 형성된 것으로 나타났다. 이렇게 작은 변형량이 발생한 것은 나사부, 가스방출구, 스템 및 스핀들 축이 장착되는 포트, 안전밸브 포트로 구성되는 수평식 가스밸브의 평형이 잘 이루어지도록 설계되었기 때문이다. 반면에 나사부와 가스방출구에 가스내압이 작용할 때, 기존 차단기능형 수직식 가스밸브의 상단부에서 최대 변형량 0.076mm가 형성된 것으로 나타났다. 가스유출구의 좌측 끝단부에서 두 번째로 큰 최대 변형량 0.055mm가 발생하였다. 이러한 변형량은 차단기능형 안전장치의 그루브에 삽입된 오링의 밀봉간극에 영향을 미칠 가능성이 높다. 따라서 본 연구에서는 LPG 용기용 가스밸브의 가스누출을 완벽하게 차단할 수 있는 메커니즘을 갖춘 차단기능형 수평식 가스밸브가 수직식 가스밸브에 비해 우수하다할 수 있다.

• Geomechanics and Engineering
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• 제14권5호
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• pp.421-428
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• 2018

In deep mining, the lateral deformation of strip coal pillar appears to be a new characteristic. In order to study the lateral deformation of coal-mass, a monitoring method and monitoring instrument were designed to investigate the lateral deformation of strip coal pillar in Tangkou Coalmine with the mining depth of over 1000 m. Because of without influence of repeated mining, the bedding sandstone roof is easy to break and the angle between maximum horizontal stress and the roadway is small, the maximum lateral deformation is only about 287 mm lower than the other pillars in the same coalmine. In deep mining, the energy accumulation and release cause a discontinuous damage in the heterogeneous coal-mass, and the lateral deformation of coal pillar shows discontinuity, step and mutation characters. These coal-masses not only show a higher plasticity but also the high brittleness at the same time, and its burst tendency is more obvious. According to the monitoring results and theoretical calculations, the yield zone of the coal pillar width is determined as 15.6 m. The monitoring results presented through this study are of great significance to the stability analysis and design of coal pillar.

• 한국융합학회논문지
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• 제7권1호
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• pp.161-166
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• 2016

본 연구에서는 타이로드 엔드의 형상에 따른 변형량과 응력, 피로 수명을 연구하였으며, 총 세 가지 형상을 가진 타이로드 엔드들을 CATIA 프로그램으로 3차원으로 모델링 한 뒤, ANSYS 유한요소해석 프로그램으로 시뮬레이션 해석을 수행하였다. 타이로드 엔드 모델의 형상별로는 모델 A, B 및 C가 있다. 본 연구 결과로서는 모델 A형의 최대 변형량, 최대 등가 응력 및 최대 피로수명들은 각각 0.0614mm, 160.27MPa 및 336,930cycle로 나타났으며, 모델 B형의 최대 변형량, 최대 등가 응력 및 최대 피로수명들은 각각 0.0648mm, 90.889MPa 및 1,171,000cycle로 나타났다. 또한 모델 C형의 최대 변형량, 최대 등가 응력 및 최대 피로수명들은 각각 0.0402mm, 84.794MPa 및 20,000,000cycle로 나타났다. 이러한 결과 값들을 통하여 형상에 따른 타이로드 엔드 모델들의 내구성을 예측할 수 있었고, 보다 진보된 타이로드 엔드의 설계 및 개발을 위한 데이터를 확보할 수 있었다. 또한 디자인 면에서 융합 기술로의 접목도 가능하여 미적인 감각물로 나타낼 수 있다.

• Nuclear Engineering and Technology
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• 제53권5호
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• pp.1556-1568
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• 2021

The plate-type fuel assembly adopted in nuclear research reactor suffers from complicated effect induced by non-uniform irradiation, which might affect stress conditions, mechanical behaviors and thermal-hydraulic performance of the fuel assembly. This paper is the Part II work of a two-part study devoted to analyzing the complex unique mechanical deformation and thermal-hydraulic characteristics for the typical plate-type fuel assembly under irradiation effect, which is on the basis of developed and verified numerical thermal-fluid-structure coupling methodology under irradiation in Part I of this work. The mechanical deformation, thermal-hydraulic performance and Mises stress have been analyzed for the typical plate-type fuel assembly consisting of support plates under non-uniform irradiation. It was interesting to observe that: the plate-type fuel assembly including the fuel plates and support plates tended to bend towards the location with maximum fission rate; the hot spots in the fuel foil appeared at the location with maximum thickness increment; the maximum Mises stress of fuel foil was located at the adjacent location with the maximum plate thickness increment et al.

• 소성∙가공
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• 제31권2호
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• pp.64-72
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• 2022

Since aluminum alloys experience both tensile and compression deformation modes during forming process, it is important to understand the role of deformation mode on the hot formability of metallic alloys. In the present work, the hot formability of Al7050 alloy was investigated by conducting both tensile and Gleeble tests at various temperatures and strain rates. Processing maps representing low efficiency regions were observed at low temperature and high strain rate in both tensile and compressive deformation modes while the maximum efficiency regions depended on different deformation modes. Moreover, samples tested at stable processing conditions presented a smaller pore fraction than those at instable conditions that resulted in crack initiation during plastic deformation. This result shows that different deformation modes during plastic forming can affect formability changes of metallic alloys. Understanding of tension-compression behaviors will help us solve this problem.

• Journal of Magnetics
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• 제16권3호
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• pp.294-299
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• 2011

Nd-Fe-B high performance magnets were prepared by die-upset forging. The effects of the deformation parameters on magnetic properties and flow stress were studied. Deformation temperatures in the range of $600{\sim}900^{\circ}C$ enable to achieve an effective anisotropy and temperature $800^{\circ}C$ proves to be suitable for deformation of Nd-Fe-B magnets. The amount of c-axis alignment along the press direction seems to depend on the amount of deformation and a saturation behavior is shown at deformation ratio of 75%. Magnetic properties are also related to strain rate, and maximum energy product is attained at an optimum strain rate of ${\varphi}=1{\times}10^{-2}s^{-1}$. By analyzing the relationship of stress and strain at different deformation temperature during die-upset forging process, deformation behavior of Nd-Fe-B magnets was studied and parameters for describing plastic deformation were obtained. Nd-rich boundary liquid phase, which is additionally decreasing the flow stress during deformation, is supposed to play the role of diffusion path and enhance the diffusion rate.

• 한국기계가공학회지
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• 제7권3호
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• pp.12-16
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• 2008

The state of deformation and stress and the structural safety are studied at the main frame composed with car body by the impact of front, offset and overturn in this study. The values of maximum deformation and von-Mises stress in case of offset impact are 2 to 3 times as high as those in case of front or offset impact at the parts of front and middle legs of roll cage. The case of front impact is of the greatest safety as compared with the case of offset or overturn impact. As there is a great stress on the side in case of overturn impact, this value is more than 2 times as low as that in case of offset impact. But there is a great possibility of overturn by the buckling on both sides in case of overturn impact.

• 한국기계가공학회지
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• 제10권3호
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• pp.47-52
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• 2011

A tracked vehicle is dependent on performance of power pack and suspension systems. Especially, road wheels which are components of suspension system contribute distributing vehicle weight on soil and preventing from misguiding tracks. In this study, the maximum force was calculated that a tracked vehicle is driven on the worst condition. And then, FE analyses were carried out to evaluate strength road wheel under maximum force condition. In standard of quality evaluation for road wheel, FE simulations and experimental works were carried out under thirty degree slant load of normal direction of shaft. And then, A relationship residual deformation for slant load was investigated. The result of this research is applicable to evaluate strength and to make use of basis data.

• 한국철도학회논문집
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• 제9권3호
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• pp.251-256
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• 2006

This paper explains manufacturing process, analysis and experimental studies on a hybrid composite carbody of Korean tilting train. The composite carbody with length of 23m was manufactured as a sandwich structure composed of a aluminium honeycomb core and woven fabric carbon/epoxy faces. In order to evaluate deformational behavior of the composite carbody, the static load test under vertical load has been conducted. From the test, the vertical deflection an겨 cross sectional deformation of the carbody were analysed and measured. The maximum deflection along the side sill was 9.25mm in the experiment and 8.28mm in the analysis. The maximum cross sectional deformation was measured 5.42mm at carbody center in lateral direction and 4.06mm at roof center in vertical direction.