• Title, Summary, Keyword: Thermal Stress

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The effect of corner shape in the casting mould on thermal stresses distribution (金型의 모서리부 形狀이 熱應力分布에 미치는 影響)

  • 민수홍;구본권;김옥삼
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.2
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    • pp.567-574
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    • 1991
  • In this study thermal stress generated in three ingot moulds(GC25) during the solidification process of aluminum were analyzed by the two-dimensional thermo-elasto-plastic theory. In temperature analysis, all of the three models are shown steep temperature rising each case in initial stage of cooling. In thermal stress analysis, all of three models took compressible stress on inside wall of the mould, and tensible along with on out side. Model 2 take place less compressible, tensible stress then model 1. But model 3. have similar as thermal stress as model 2. The analysis will made one possible to calculate an optimum mould shape whose thermal stress gradient becomes minimum.

Thermal Stress Analysis of Functuonally Graded Ceramic/Metal Composites(II) (경사기능성 세라믹/금속 복합재료의 열응력해석)

  • Lim, Jae-Kyoo;Song, Jun-Hee
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.10
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    • pp.1571-1579
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    • 1997
  • The development of a new material which should be continuously use under severe environment of very high temperature has been urgently requested. For the development of such super-heat resistant materials, the main problem is not only to make the superior thermal barrier properties but also to actively release thermal stress. So, a new concept of functionally graded material(FGM) has been proposed to overcome this problem. A composition and microstructure of FGM are varied continuously from place to place in ways designed to provide it with the maximum function of mitigating the induced thermal stress. So, FGM can be applied in the aerospace, the electronic and the medical field, etc.. In this study, thermal stress analysis of sintering PSZ/NiCrAlY graded material was conducted theoretically using a finite-element program. The temperature condition was sintering temperature assuming a cooling-down process up to room temperature. Fracture damage mechanism was anlayzed by the parameters of residual stress. It could be known that FGM provided with the function of mitigating the induced thermal stress.

Thermal stress analysis around a cavity on a bimetal

  • Baytak, Tugba;Bulut, Osman
    • Structural Engineering and Mechanics
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    • v.69 no.1
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    • pp.69-75
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    • 2019
  • The plates made of two materials joined to each other having the different coefficient of thermal expansions are frequently encountered in the industrial applications. The stress analysis of these members under the effect of high-temperature variation has great importance in design. In this study, the stress analysis of the experimental model developed for the problem considered here was performed by the method of photothermoelasticity. The thermal strains were formed by the mechanical way and these were fixed by the strain freezing method. For the stress measurements, the method of slicing is applied which provides three-dimensional stress analysis. The analytical solution in the literature was compared with the related stress distribution obtained from the model. Moreover, the axisymmetric finite element model developed for the problem was solved by ABAQUS and the results obtained here compared with those of the experimental model and the analytical solution. As a result of this study, this experimental method and numerical model can be used for these type of thermal stress problems which have not been comprehensively analyzed yet.

Design of Microstructure by Evaluating the Effect of Thermal Barrier Coating's Microstructure on TGO Interface Stress (열차폐코팅의 미세구조가 TGO 계면 응력에 미치는 영향 평가를 통한 미세구조 형상 설계)

  • Kim, Damhyun;Park, Kibum;Wee, SungUk;Kim, Keekeun;Park, Soo;Seok, Chang-Sung
    • Journal of the Korea Institute of Military Science and Technology
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    • v.23 no.5
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    • pp.435-443
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    • 2020
  • Thermal barrier coating(TBC) applied to fighter and turbine engines is a technology that improves the durability of core parts by lowering the surface temperature of base material. The thermal stress caused by mis-match of the coefficient of thermal expansion between the top coating and the TGO interface is the main cause of TBC breakage. Since the thermal stress is dependent on the microstructure of the TBC, designing microstructure of TBC can improve the durability as well as lower the thermal stress. In this study, the effect of coating thickness, volume of porosity and vertical cracking on the thermal stress was analyzed through finite element analysis. Through the analysis results, a design range of a microstructure that can improve the durability of thermal barrier coating by lowering thermal stress is proposed.

Boundary Element Analysis of Thermal Stress Intensity Factor for Interface Crack under Vertical Uniform Heat Flow (경계요소법을 이용한 수직열유동을 받는 접합경계면 커스프균열의 열응력세기계수 결정)

  • Lee, Kang-Yong;Baik, Woon-Cheon
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.7
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    • pp.1794-1804
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    • 1993
  • The thermal stress intensity factors for interface cracks of Griffith and symmetric lip cusp types under vertical uniform heat flow in a finite body are calculated by boundary element method. The boundary conditions on the crack surfaces are insulated or fixed to constant temperature. The relationship between the stress intensity factors and the displacements on the nodal point of a crack tip element is derived. The numerical values of the thermal stress intensity factors for interface Griffith crack in an infinite body and for symmetric lip cusp crack in a finite and homogeneous body are compared with the previous solutions. The thermal stress intensity factors for symmetric lip cusp interface crack in a finite body are calculated with respect to various effective crack lengths, configuration parameters, material property ratios and the thermal boundary conditions on the crack surfaces. Under the same outer boundary conditions, there are no appreciable differences in the distribution of thermal stress intensity factors with respect to each material properties. But the effect of crack surface thermal boundary conditions on the thermal stress intensity factors is considerable.

An Efficient Thermal Stress Estimation Using Block Adaptive Filtering

  • Tai, Ming-Lang
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.1269-1271
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    • 2009
  • We had proposed fast thermal stress estimation methodology for the components on system board when the system is stationary within specific ambient air temperature. Now, we will propose one efficient thermal stress estimation methodology, block adaptive filtering methodology, for the FPD electronic system board which is enclosed by mechanical cover.

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Experimental Investigation of Thermal Stress Cracks in Mechanical Face Seals (기계평면시일의 열응력 크랙에 관한 실험적 연구)

  • 김청균
    • Tribology and Lubricants
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    • v.12 no.3
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    • pp.79-84
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    • 1996
  • One of the greatest dangers in mechanical face seals is the formation of heat checking and thermal stress cracks on the sliding surfaces. These thermal distortions due to non-uniform heating lead to increase the leakage of the sealed fluids and wear, and with balance of the seal can cause the seal faces to part. In this study heat checking and thermal stress cracks are investigated experimentally. These thermal distortions are explained using the thermal models of the conatct geometries between the seal ring and the seal seat. To overcome these thermal problems, the thermohydrodynamic seal is presented. The newly developed mechanical seal may substantially reduce the friction torque, frictional heating which causes heat checking and thermal stress cracks, and wear.

Bounary Element Analysis of Thermal Stress Intensity Factors for Cusp Cracks (커스프 균열에 대한 열응력세기 계수의 경계요소해석)

  • 이강용;조윤호
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.1
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    • pp.119-129
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    • 1990
  • In case that the body with a cusp crack is under uniform heat flow, thermal stress intensity factors are calculated by using boundary element method with linearized body force term. The crack surface is under insulated or fixed temperature condition and the types of crack are symmetric lip and airfoil cusps. Numerical values of thermal stress intensity factors for a Griffith crack and cusp cracks in infinite bodies are proved to be in good agreement within .+-.5% when compared with the previous numerical and exact solutions, respectively. The thermal stress intensity factors for symmetric lip and airfoil cusp cracks in finite bodies are calculated about various effective crack lengths, configuration parameters, and heat flow directions. With the same crack surface thermal boundary conditions, heat flow directions and crack lengths, there are no appreciable differences in variations of thermal stress intensity factors between symmetric lip and airfoil cusp cracks. The signs of thermal stress intensity factors for each cusp crack are changed with each crack surface thermal boundary condition.

Thermal Stress Analysis for a Brake Disk considering Pressure Distribution at a Frictional Surface (마찰면의 압력 분포를 고려한 제동디스크의 열응력 해석)

  • Lee Y.M.;Park J.S.;Seok C.S.;Lee C.W.;Kim J.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.842-846
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    • 2005
  • A brake disk and a pad are important parts that affect the braking stability of a railway vehicle. Especially, because a brake disk stops the vehicle using conversion of the kinetic energy to frictional energy, thermal fatigue cracks are generated by the cyclic thermal load, as frictional heat, on a frictional surface and these cracks cause the fracture of a brake disk. Therefore, many researches for the thermal stress must be performed to improve the efficiency of brake disk and ensure the braking stability. In this study, we performed the thermal stress analysis for a ventilated brake disk with 3-D analysis model. For that, we simplified the shape of a ventilated hole to minimize problems that could be occurred in analysis process. Thermal stress analysis was performed in case that pressure distributions on a frictional surface is constant and is not. To determine pressure distributions of irregular case, pressure distribution analysis for a frictional surface was carried out. Finally using the results that were obtained through pressure distribution analysis, we carried out thermal stress analysis of each case and investigated the results of thermal stress analysis.

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Thermal Stress Analysis for the Printed Circuit Board of Electronic Packages (전자장비 회로기판의 열응력해석)

  • Kwon Y. J.;Kim J. A.
    • Korean Journal of Computational Design and Engineering
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    • v.9 no.4
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    • pp.416-424
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    • 2004
  • In this paper, the heat transfer analysis and thermal stress analysis of the PCB(Printed Circuit Board) equipped in electronic Packages are carried out for various may types of chips on the PCB. And two structural PCB models are used in the analyses. The electronic chips on the PCB usually emit heat and this heat generates the thermal stress around the chip. The thermal load due to the heat generation of chips on the PCB may cause the malfunction of the electronic packages such as a monitor. a computer etc. Hence, the PCB should be designed to withstand these thermal loads. In this paper, the heat transfer analysis and thermal stress analysis are executed for the PCB model with pins and the analysis results are compared with the results for the PCB model without pins. The analysis results show that the PCB model without pins is not good for the thermal stress analysis of PCB, even though these two models have similar heat transfer characteristics. The analysis results also show that the highest thermal stress occurs in the pin especially attached to the highest temperature chip, and the PCB constrained to the electronic package on the long side is structurally more stable than other cases. The analyses of the PCB are executed using the finite element analysis code, NISA.