• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.54-57
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• 2000

Thermal deformation behavior has been investigated for unsymmetric laminates composed of various kinds of material layers, such as stainless steel, aluminum, carbon/epoxy or glass/epoxy. The thermal deformations of unsymmetric laminates were predicted using the classical lamination theory and compared with those obtained from experimental measurement. In the case of unsymmetric laminate composed of stainless steel and aluminum layer, the experimental results were agreed well with the values predicted. But in the case of unsymmetric laminate composed of fiber composite layers, there was a considerable difference of thermal deformation between the prediction and experimental measurement, which may be from the change of material properties of fiber composite layers for temperature variation.

• Journal of the Korean Society of Safety
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• v.18 no.4
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• pp.39-43
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• 2003

An experimental study was conducted to develop and understanding of fracture behavior of ceramic thermal barrier coating when subjected to a thermal shock loading. The thermal loading was applied using a 1.5kW $CO_2$ laser. In the experiments, beam-shaped specimens were subjected to a high heat flux for 4sec and cooling of 7sec in air. The interface crack length was increased as the crack density, the surface pre-crack legth and the coating thickness were increased. The center surface crack length was increased as the maximum surface temperature got higher and the surface pre-crack length for shorter.

• Tribology and Lubricants
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• v.28 no.5
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• pp.246-251
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• 2012

Disc brakes and brake linings are part of the braking system in automobiles; this system works due to the braking power between the disc and pad. Vehicle braking systems have complex environments due to the geometry of the disk and pad, the material properties, the braking conditions, etc. Braking energy is converted into thermal energy during the braking process, due to the frictional heat between the disc brake and pad. This heat is changed to a heat flux, which affects the thermal stress of the disc. The purpose of this study was to use the fluid dynamics software ANSYS CFX to investigate the inner flow characteristics of the air and the heat transfer of the disc, and to analyze the effects on the thermal stress of the disc brake.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.363-366
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• 1999

This paper describes the behavior of prestressed concrete storage tanks under cryogenic temperatures by thermal stress analysis. In concrete tanks to store up LNG, a thermal shock can occur over a global area resulting from the sudden filling of the outer tank with cryogenic storage contents. Analysis results show that internal surface of concrete tank is cooled down rapidly. Tank is subjected mostly to thermal constraint moment due to temperature gradient across its section. Constraint moment may cause tensile stresses beyond tensile strength in the wall. Problems related with concrete cracking due to temperature gradient have been considered.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1436-1441
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• 2006

Each type of optical sheets in a LCD module experiences a characteristic behavior for thermal loading and unloading. During thermal cycling, a polymeric behavior is reversible and recyclable, depending on a material stiffness critically affected by temperature and time. Some critical issues on temperature- and time-dependent themomechanical deformation of the polymeric sheet are addressed by finite-element thermal results, followed by structural simulation results in this study.

• Journal of Mechanical Science and Technology
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• v.15 no.7
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• pp.823-830
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• 2001

The single fiber pull-out technique has been commonly used to characterize the mechanical behavior of fiber/matrix interface in fiber reinforced composite materials. In this study, an improved analysis considering the effect of thermal residual stresses in both radial and axial directions is developed for the single fiber pull-out test. It is found to have the pronounced effects on the stress transfer properties across the interface and the interfacial debonding behavior.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.767-774
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• 2007

Even though a constant repeated load is applied, plastic deformation may cumulate. This kind of behavior is called ratcheting. Ratcheting may lead to cracks and finally to failure of the rail. Usually ratcheting occurs on high rails in curves. Ratcheting is influenced by residual stresses, wheel-rail contact stresses, thermal stresses due to wheel/rail rolling contact, shear strength of the rail, strain hardening behavior, etc. In this study, contact stresses and thermal stresses are examined. It is found their value is considerable compared to the maximum contact pressure.

• Journal of Power Electronics
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• v.14 no.6
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• pp.1345-1356
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• 2014

The thermal behavior of power modules is an important criterion for the design of cooling systems and optimum thermal structure of these modules. An important consideration for high power and high frequency design is the spacing between semiconductor devices, substrate structure and influence of the boundary condition in the case. This study focuses on the thermal behavior of hybrid power modules to establish a simplified method that allows temperature estimation in different module components without decapsulation. This study resulted in a correction of the junction temperature values estimated from the transient thermal impedance of each component operating alone. The corrections depend on mutual thermal coupling between different chips of the hybrid structure. A new experimental technique for thermal mutual evaluation is presented. Notably, the classic analysis of thermal phenomena in these structures, which was independent of dissipated power magnitude and boundary conditions in the case, is incorrect.

• Fashion & Textile Research Journal
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• v.11 no.3
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• pp.474-480
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• 2009

The purpose of this study is to prepare the hardness of polyester(PET) fabric by thermal bonding with low melting component of bicomponent fiber and to describe the change of physical properties of thermal bonded PET fabrics. The PET fabrics were prepared with regular PET fiber as warp and bicomponent fiber as weft. The bicomponent fiber of sheath-core type were composed with a regular PET core and low melting PET sheath. The thermal bonding of PET fabric was carried out in pin tenter from 120 to $195^{\circ}C$ temperature range for 60 seconds. In this study, we investigated the physical properties and melting behavior of PET fiber and the effect of the temperature of the pin tenter on the thermal bonding, mechanical properties. Melting peak of warp showed the thermal behavior of general PET fiber. However, melting peak of weft fiber(bicomponent fiber) showed the double melting peak. The thermal bonding of the PET fabric formed at about temperature of lower melting peak. The optimum thermal bonding conditions for PET fabrics was applied at $190{\sim}195^{\circ}C$ for 60seconds by pin tenter. On the other hand, the tensile strength of the PET fabric decreased with an increasing temperature of thermal bonding.

• Korean Journal of Materials Research
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• v.27 no.1
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• pp.25-31
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• 2017

This study investigates changes in the mechanical behaviors, especially hardness and indentation load-displacement curves, of thermal barrier coatings (TBCs) brought about by thermal shock. The TBCs on the Nickel-based bondcoat/superalloy was prepared with diameters of 25.4 mm and $600{\mu}m$ thickness. The results of thermal shock cycling test from $1100^{\circ}C$ of the highest temperature indicate that the thermal shock do not influence on the mechanical behavior, but a continuous decrease in porosity and increase in hardness were observed after 1200 thermal shock cycles; these changes are believed to be due to sintering of thermal barrier coating materials. The results that no degradation in the indentation load-displacement curves indicate that the coating shows good thermal shock resistance up to 1200 cycles at $1100^{\circ}C$ in air.