• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.4
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• pp.887-902
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• 1994

Within the framework of anisotropic thermoelasticity, the problem of an interlaminar crack in a laminated fiber-reinforced composite subjected to a uniform heat flow is investigated. Under a state of generalized plane deformation, dissimilar anisotropic half-spaces with different fiber orientations are considered to be bound together by a matrix interlayer containing the crack. The interlayer models the matrix-rich interlaminar region of the fibrous composite laminate. Based on the flexibility/stiffness matrix approach, formulation of the current crack problem results in having to solve two sets of singular integral equations for temperature and thermal stress analyses. Numerical results are obtained, illustrating the parametric effects of laminate stacking sequence, relative crack size, crack location, crack surface partial insulation, and fiber volume fraction on the values of mixed mode thermal stress intensity factors.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.1
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• pp.65-70
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• 2001

The hear transfer mechanism initiating the friction welding is examined and a transient three dimensional heat conduc-tion model for the welding of two dissimilar cylindrical metal bars is investigated. The cylindrical metal bars are made of materials made of A2024 and SM 45C. Numerical simulations of heat flow are performed using the finite volume method. Respectively. Commercial FLUENT code is used in the heat flow simulation and maximum temperature and distribution of temperature are calculated. Temperature of friction welded joining face is compared with the temperature distribution measured by experiment and numerical simulation. The maximum temperature of friction welded joining face is lower than melting point of A2024-T6 aluminum alloy using insert metal. The temperature distribution of friction welded join- ing face with insert metal is more uniform than that of without inset metal.

• Laser Solutions
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• v.2 no.1
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• pp.61-67
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• 1999

This study introduces the new concept in the evaluation criteria of the $CO_2$ laser Tailored Blank weldability, The materials used are 0.7mm, 1.5mm thick low carbon automotive galvanized steels. Welding tests were conducted for both similar thickness(0.7mm-0.7mm, 1.5mm-1.5mm) and dissimilar thickness(0.7mm-1.5mm) cases. The criteria developed for optimum welding conditions were based on relationship between results of die press forming test, weld transverse tensile test Erichsen test and weld penetration measurements. Application of the developed criteria(fracture ratio, strength ratio and D/To) in obtaining optimum welding condition revealed that a weld which satisfied any of the criteria did not fracture during actual die press test.

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.331-336
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• 2004

The phase change due to the reflection from target surfaces in a white-light interferometer induces measurement errors when target surfaces are composed of dissimilar materials. We prove that this phase change on reflection as the polarization of the white-light changes causes a shift of both envelope peak position and fringe peak position of several tens of nanometers as the polarization of the white-light changes. In addition, we propose a new equation for white-light interference fringes depending on the polarization of the source.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.78-81
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• 2000

The test specimen proposed in this study, named the bimaterial eccentric compression specimen, is a rectangular prism of two dissimilar materials with a notch at their interface. Normalized energy release rates and phase angles were calibrated with the finite element method. The normalized energy release rate increases with notch ratio but decreases with E2/E2, loading point, and phase angle, Bimaterial specimens consisting of mortar and ploymer as well as mortar and rock were prepared and tested to simulate fracture behavior ar the interface. Test results have confirmed that initial notch has significant effect on the apparent interfacial toughness.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.10a
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• pp.42-46
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• 2000

In this paper, joints of Cu-1Cr-0.1Zr alloy to STS316L were performed by friction welding method. Cu-1Cr-0.1Zr alloy is attractive candidate as nuclear power plant material and exibit the best combination of high sts good electrical and thermal conductivity of any copper alloy examined. The stainless steel is a structural material who alloy acts as a heat sink material for the surface heat flux in the first wall. So, in this paper, not only the develop optimizing of friction welding with more reliability and more applicabililty but also the development of in-process rear quility(such as strength and toughness) evaluation technique by acoustic emission for friction welding of such nuclear component of Cu-1Cr-0.1Zr alloy to STS316L steel were performed.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.10a
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• pp.26-32
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• 2000

It was confirmed that the life predictive equation by LMP-ISM are effective only up to 10$^2$hours and can not be used for long times of 10$^3$~10$^{5}$ hours, but that by ISM can be used for long times creep life prediction with more reliability. The predictive creep life equation of ISM has better reliability than those by LMP and LMP-ISM, and its realizably is getting better for long time creep prediction(10$^3$~10$^{5}$ H).

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.104-109
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• 2008

Distribution of welding residual stresses are mainly characterized by degrees and frequencies of thermal loads applied to materials. However, other effects as component size and clamping condition can also affect stress distributions to a certain extent thus careful manipulation of these parameters based on clear understanding of how they affect residual stresses distributions and why can be additional measure to mitigate residual stresses. This paper discusses aforementioned issues for the case of safety and relief nozzle in nuclear power plant through finite element analysis.

• Journal of Welding and Joining
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• v.26 no.6
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• pp.48-53
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• 2008

Although Magnetic Pulse Welding(MPW) is not a recently developed technique, it has gained the attention of the automotive industry. MPW has become an accepted welding process because it enables the joining of similar, and dissimilar materials, with a very short cycle time, without the need for filler metal and gases. In this study, the effect of the stand-off distance on the weld strength has been investigated. The compressive strength of the MPW joints was evaluated using UTM. The interface of weld, IMC composition and morpology were studied by SEM and EDS. It was concluded that the stand-off distance and the voltage are the main parameters influencing the strength of weld. In case of too high stand-off distance, it influenced harmful effect because of the resistance of deformation.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.141-143
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• 2007

Increasing demand of using low weight materials in recent automotive trends has been the challenge to develop a sound welding of aluminum alloys. A heat treatable AA6082-T6 and a non-heat treatable AA5083-0 aluminum alloys were joined in this study. Investigations revealed that about 60 UTS will be reduced due to welding process. Fracture happened in the interface between fusion zone and base metal of top specimen where penetration is shallow. Therefore, lower welding torch angle produced the better strength which allows deeper penetration to the top specimen. PWHT at $560^{\circ}C$ for 2 hours can be used to return the original UTS of the specimens.