• 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.

• Journal of the Korean Society of Clothing and Textiles
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• v.47 no.6
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• pp.1193-1203
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• 2023

This study aims to provide primary data regarding the thermal stress of disposable personal protective coveralls. Thermal stress and surface temperature measurements were taken among ten men wearing coveralls. The size of the ten men corresponds to a size eight in Size Korea. As a result of thermal stress, sensations of humidity and discomfort were higher when wearing Level C compared to Level D. Level D felt significant thermal stress in their upper body after exercise. However, they did not feel such stress in their lower body. Level C felt thermal stress in their upper and lower body after exercise. In addition, in Level C, the ratings of perceived exertion blood pressure and pulse rate after exercise were higher than those of Level D. Furthermore, the surface temperature of disposable personal protective coveralls among Level C was slightly higher than that of Level D.

• 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.

• 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.

• 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.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.7 s.94
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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.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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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.

• 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.

• 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.

• 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.