• 제목/요약/키워드: Residual solid

검색결과 239건 처리시간 0.021초

고체-고체-기체 화학 열펌프 시스템의 반응기 설계에 관한 연구 (A Study on the Reactor Design of Solid-Solid-Gas Chemical Heat Pump System)

  • 김성준;이태희;;최홍규;이종호
    • 설비공학논문집
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    • 제6권4호
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    • pp.406-416
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    • 1994
  • In this study the reactor design procedure and method of solid-solid-gas chemical heat pump system using STELF technology were investigated. For manufacturing IMPEX block which is the kernel of reactor, proper salt pair should be selected, and equilibrium temperature drop and COP should be examined for selected salt pair. Moreover, apparent density, residual porosity, and graphite ratio should be calculated to give minimum block volume and mass, and maximum energy density without causing heat and mass transfer problems. Since heat exchange area can be changed with operating condition, reactor diameter, length, and stainless steel thickness should be decided for desired specifications. These procedure and method were applied to the case study of 6kW cold production and 8 hours storage capacity reactor.

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상변태를 고려한 탄소강 용접부의 잔류응력 해석에 관한 연구 (A Study on the Analysis of Residual Stress in Weldment by Considering the Phase Transformation of Carbon Steel)

  • 조시훈;김재웅
    • 대한기계학회논문집A
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    • 제25권3호
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    • pp.390-398
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    • 2001
  • Welding process generates distortion and residual stress in the weldment due to rapid heating and cooling. Welding distortion and residual stress in the welded structure result in many troubles such as dimensional inaccuracies in assembling and safety problem during service. The accurate prediction of welding residual stress is thus very important to improve the quality of weldment and find the way to reduce itself. This paper suggests new analysis method to predict welding residual stress by considering solid phase transformation during welding process. Using the method, analysis is performed for medium and low carbon steel. The analysis result for medium carbon steel reveals that case considering phase transformation has compressive residual stress in contrast with the case neglecting phase transformation because of martensite formation. However, for the case of low carbon steel, residual stress shows little difference between the case considering phase transformation and the other case, because it has small transformation strain and recovers rapidly stress after phase transformation.

Point interpolation method based on local residual formulation using radial basis functions

  • Liu, G.R.;Yan, L.;Wang, J.G.;Gu, Y.T.
    • Structural Engineering and Mechanics
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    • 제14권6호
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    • pp.713-732
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    • 2002
  • A local radial point interpolation method (LRPIM) based on local residual formulation is presented and applied to solid mechanics in this paper. In LRPIM, the trial function is constructed by the radial point interpolation method (PIM) and establishes discrete equations through a local residual formulation, which can be carried out nodes by nodes. Therefore, element connectivity for trial function and background mesh for integration is not necessary. Radial PIM is used for interpolation so that singularity in polynomial PIM may be avoided. Essential boundary conditions can be imposed by a straightforward and effective manner due to its Delta properties. Moreover, the approximation quality of the radial PIM is evaluated by the surface fitting of given functions. Numerical performance for this LRPIM method is further studied through several numerical examples of solid mechanics.

Study on the mechanical behaviors of timber frame with the simplified column foot joints

  • Yang, Qing-shan;He, Jun-xiao;Wang, Juan
    • Structural Engineering and Mechanics
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    • 제77권3호
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    • pp.383-394
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    • 2021
  • Column foot in traditional Chinese timber structures may be subjected to be uplifted due to the lateral load and subsequently reset under the vertical loads. The residual moment of the rocking column foot is the most important parameter representing the mechanical behaviors of column foot, and the simplification of joints is the basis of structural analysis of whole structure. The complicated mechanical behaviors of joint and the modeling of the column foot joint has been undertaken historically based on the experiments and numerical simulation. On the condition of limited application range of those models, a lack of simplified model to represent the mechanical behaviors of joint deserves attentions. There is a great need to undertake theoretical studies to derive the residual moment and make better simplified model of the joint. This paper proposes the residual moment and equivalent simplified model of the rotational stiffness for column foot joint. And, the timber frame is established based on the simplified model, which is verified by solid finite element model. Results show that a mutual agreement on the mechanical behaviors of the timber frame is obtained between the simplified model and the solid finite element model. This study can serve as the references of the structural analysis for the traditional timber structures.

PoC 부착 싸이클론의 미세분진 유출 제어에 관한 연구 (Emission Control of Fine Dust from Gas-Solid Cyclone)

  • 조영민
    • 한국대기환경학회지
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    • 제15권2호
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    • pp.201-210
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    • 1999
  • Cyclones have been extensively used in the industry for removing fine particles from the gaseous streams, based on simplicity in design and construction in association with low cost and flexibility to operate in extreme and harsh environments. However, industrial cyclones are typically not very efficient for particles smaller than 10μm. In this work, in order to improve the separation efficiency of reverse flow cyclones, a simple device named Post Cyclone(Poc) in installed on the top of an existing cyclone. Thereby the residual swirl present at the outlet (vortex finder) of a conventional cyclone has been used to capture the escaped dust from the cyclone in the PoC. The performance of PoC was closely evaluated by changing configuration of the PoC and operation condition. In addition, the dust behaviour in th PoC was investigated based on the hypothesis of residual vortex.

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Residual stresses measurement in the butt joint welded metals using FSW and TIG methods

  • Taheri-Behrooz, Fathollah;Aliha, Mohammad R.M.;Maroofi, Mahmood;Hadizadeh, Vahid
    • Steel and Composite Structures
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    • 제28권6호
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    • pp.759-766
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    • 2018
  • Friction Stir Welding (FSW) is a solid-state process, where the objects are joined together without reaching their melting point. It has been shown that this method is a suitable way to join dissimilar aluminium alloys. The current article employed hole drilling technique to measure the residual stress distribution experimentally in different zones of dissimilar aluminium alloys AA6061-T6 and AA7075-T6 Butt welded using FSW. Results are compared with those of similar AA6061-T6 plates joined using a conventional fusion welding method called tungsten inert gas (TIG). Also, the evolution of the residual stresses in the thickness direction was investigated, and it was found that the maximum residual stresses are below the yield strength of the material in the shoulder region. It was also revealed that the longitudinal residual stresses in the joint were much larger than the transverse residual stresses. Meanwhile, Vickers micro hardness measurements were performed in the cross-section of the samples. The largest hardness values were observed in the stir zone (SZ) adjacent to the advancing side whereas low hardness values were measured at the HAZ of both alloys and the SZ adjacent to the retreating side.

Solid Phase Microextraction법을 이용한 식품포장재 중의 잔류용제 분석 (Analysis of Residual Solvents in Food Packaging Materials Using Solid Phase Microextraction Method)

  • 서택교;박상현;이윤수;김정한;권익부
    • 한국식품위생안전성학회지
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    • 제14권1호
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    • pp.76-83
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    • 1999
  • Solid phase microextraction (SPME) was used for the determination of 6 standard solvents (methanol, isopropanol, methyl ethyl ketone, ethyl acetate, cyclohexane, toluene) in food packaging materials. SPME method is a solvent-free sample preparation technique in which a fused silica fiber coated with polymeric organic liquid is introduced into the headspace above the sample. SPME method using fiber coated polydimethylisiloxane (PDMS) was compared with static headspace (SHS) method used as a reference. It was found that the optimal adsorption condition using PDMS-SPME method was 2$0^{\circ}C$ for 15 minutes for the standard solvents. Detection limits, linearity, reproducibility and recovery of both SHS and PDMS-SPME methods have been determined using 6 standard solvents. Both methods were characterized by high reproducibility and good linearity. Using SHS methods, the mean recovery of the 6 standard solvents was ranged from 75.5% to 105.8% with a mean relative standard deviation (RSD) of 0.3% to 4.8%. With PDMS-SPME method, the mean recovery of the 6 standard solvents was ranged from 86.7% to 108.3% with a mean RSD of 0.4% to 2.5%. The detection limits of both methods were the same for toluene, cyclohexane and methyl ethyl ketone; those of PDMS-SPME method were higher than those of SHS method for methanol, isopropanol and ethyl acetate. PDMS-SPME fiber shoed excellent adsorption for non-polar solvents such as toluene, while it showed relatively low adsorption for polar solvents such as methanol.

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선체 Shell FE 모델 내 용접부의 Solid 요소변환 자동화 시스템 (Pre-processing System for Converting Shell to Solid at Selected Weldment in Shell FE Model)

  • 유진선;하윤석
    • Journal of Welding and Joining
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    • 제34권2호
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    • pp.11-15
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    • 2016
  • FE analyses for weldment of ship structure are required for various reasons such as stress concentration for bead tow, residual stress and distortion after welding, and hydrogen diffusion for prediction of low temperature crack. These analyses should be done by solid element modeling, but most of ship structures are modeled by shell element. If we are able to make solid element in the shell element FE modeling it is easily to solve the requirement for solid elements in weld analysis of large ship structures. As the nodes of solid element cannot take moments from nodes of shell element, these two kinds of element cannot be used in one model by conventional modeling. The PSCM (Perpendicular shell coupling method) can connect shell to solid. This method uses dummy perpendicular shell element for transferring moment from shell to solid. The target of this study is to develop a FE pre-processing system applicable at welding at ship structure by using PSCM. We also suggested glue-contact technique for controlling element numbers and element qualities and applied it between PSCM and solid element in automatic pre-processing system. The FE weldment modeling through developed pre-processing system will have rational stiffness of adjacent regions. Then FE results can be more reliable when turn-over of ship-block with semi-welded state or ECA (Engineering critical assessment) of weldment in a ship-block are analyzed.

쇄빙선의 내충격 특성에 관한 실험적 연구: 제2부 선체 구조의 충격 굽힘 특성 (Study on Crashworthiness of Icebreaker Steel: Part II Ship Side Structural Behavior Due to Impact Bending)

  • 노명현;이재익;한동화;정준모
    • 한국해양공학회지
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    • 제30권4호
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    • pp.277-286
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    • 2016
  • The first part of this study found the tendencies of the mechanical properties of two arctic structural steels (EH32 and FH32). In the second part, the crashworthiness of stiffened panels scaled down from the side frame structure of a Korean research icebreaker was determined. A procedure for designing the shapes and sizes of the stiffened panels, mass and shape of a drop striker, and a large temperature chamber, and then manufacturing these, is introduced in detail. From impact bending tests for the stiffened panels, the residual permanent deformations and deformation histories over time were captured using manual measurement and video image analyses. Numerical simulations of the impact bending tests were carried out for three different finite element models, which were mainly composed of shell elements, solid elements, and solid elements, with welding beads. It was proven from a comparison of the test results and numerical simulation results that the solid element model with the welding bead consideration approached the test results in terms of the residual deformations as long as the strain rate effect was taken into account.

Al6061-T6 열처리 잔류응력의 유한요소해석 및 측정 (FE-Simulation and Measurement of the Residual Stress in Al6061 During T6 Heat Treatment)

  • 고대훈;김태정;임학진;이정민;김병민
    • 대한기계학회논문집A
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    • 제35권7호
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    • pp.717-722
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    • 2011
  • 본 연구의 목적은 Al6061 의 T6 열처리 시 발생되는 잔류응력의 변화를 예측하는 것이다. Al6061-T6 의 일반적인 열처리 조건인 용체화처리($530^{\circ}C$, 2hr)와 인공시효($175^{\circ}C$, 9hr)에서 인공시효 시간에 따라 잔류응력 변화를 고려하였다. 잔류응력 예측은 열처리 실험을 수행하여 대류 열전달계수를 확보하고, 탄소성 모델로 가정한 유한요소해석을 적용하였다. 또한 인공시효와 같이 재료가 고온에서 장시간 유지되는 경우의 Zener-Wert-Avrami 함수를 적용하여 잔류응력 변화를 확인하였다. 잔류응력의 측정은 X 선 회절법으로 측정하고 측정결과는 예측된 유한요소해석 결과와 비교하여 해석의 신뢰성을 확보하고 해석기법을 확립하였다.