• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.1
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• pp.170-180
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• 1995

A parallel crack in bonded dissimilar orthotropic planes under out-of-plane loading is analyzed. The problem is formulated by Fourier integral transforms, and reduced to a pair of dual integral equations. By solving the integral equations, the asymptotic stress and displacement fields near the crack tip are determined in closed form, from which the stress intensity factor and energy release rate are obtained. Discontinuity in the stress intensity factor as the distance ratio h/a of the parallel crack approaches zero is found, while the energy releas rate is shown to be continuous at h/a = 0. This information can immediately be used to generate the stress intensity factor for the parallel crack near the interface. By employing "the maximum energy release rate criterion", it could be shown in the case of no existing crack initially that the parallel crack is formed far from the interface for the more compliant material, while it is formed close to the interface for the stiffer material. material.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.207-207
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• 2001

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.33-38
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• 2002

Nowdays, related with vehicle weight reduction, many automotive maker are trying to develop spaceframe. If aluminum member and steel member are applied together in constructing spaceframe, there will be many advantages in aspect of inclosing strength and saving weight of automotive. In this case, joining method of aluminum and steel members has to be proposed. For this method, electomagnetic joining has many advantages compared to welding. In this paper, joining of aluminum tube and steel tube using eletomagnetic pressure was studied and strength of joint was evaluated through commission test.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.785-790
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• 2002

Distributions of residual stress in diffusion bonding of dissimilar materials intermetallics TiAl to steel 40Cr were simulated by FEM calculation. Results showed that destructive residual stresses presented in the minute area adjacent to bond-line of the base material with smaller coefficient of thermal expansion. Reducing bonding temperature and diminishing bonding time are in favor of the mollification of interface tresses.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.3
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• pp.256-263
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• 2009

After several PWSCCs were found in Bugey(France), Ringhals(Sweden), Tihange(Belgium), Oconee, Arkansas, Crystal Fever, Davis-Basse, VC Summer(U.S.A.), Thuruga(Japan), USNRC and PNNL started the research on PWSCC, that is, the PINC project. USNRC required KINS to participate in the PINC project in May 2005. KINS organized the Korean consortium at March 2006 and Pre-RRT for RVHP were performed for the preparation of PINC RRT. Through these preliminary RRT, Korea NDE teams can learn and develop the detection and sizing technique for RVHP dissimilar metal weld. These techniques are now being prepared in Korea and need to be utilized for the In-service inspection of the RVHP and BMI of Korea Nuclear Power Plants. PINC RRT mock-ups will be helpful to training.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.59-59
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• 2010

Friction stir welding has become a viable and important manufacturing alternative or fabrication component, especially in aerospace and automobile applications involving aluminium alloys. In recent years, there is an increasing interest for FSW of dissimilar metals and alloys, particularly systems which are difficult to weld by conventional, thermal (or fusion) welding. In this study we tried to analyse the complex heat distribution occurring in TIG assisted FSW of dissimilar butt joint (STS304 and Al6061). For this, an analytical model for heat generation by FSW based on contact conditions has been developed. The heat input was calculated considering the coefficient of friction and slip factor between each work piece material with the tool material. The thermal model is used to generate the temperature characteristics curve, which successfully predicts the maximum welding temperature in each alloys. The analysis was carried out using the in-house solver.

• Journal of Welding and Joining
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• v.31 no.4
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• pp.54-61
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• 2013

This paper reports mild steel(SPHC) and stainless steel(STS304) sheets commonly used for railroad cars or commercial vehicles such as in the automobile and shipbuilding industries. The sheets are used in these applications, which are mainly fabricated using the shielded metal arc welding(SMAW) of dissimilar materials. It also reports an interesting application of Laser Induced Breakdown Spectroscopy(LIBS) in order to determine the elemental composition diffusion of SPHC and STS304. Arc blow produced by magnetic force during the electric arc welding prevents the formation from a sound weldment. In particular, the mechanical properties of the joint are influenced by not only by geometrical and mechanical factors but also the welding conditions for the arc welded joint. Therefore, the mechanical properties and performance are evaluated by performing a physicochemical component analysis. And they increase in accordance with content of elements and microstructure in mild steel. As results, appropriate range for magnetic fields could be achieved. Therefore, the effect of magnetic force in a butt weld of mild steel plates was investigated by comparing to the measured data.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.5
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• pp.491-497
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• 2019

Dissimilar friction welding were produced using 15 mm diameter solid bar in superalloy(Alloy718) to chrome molybdenum steel(SCM440) to investigate their mechanical properties. Consequently, optimal welding conditions were n=2000 rpm, HP=60 MPa, UP=120 MPa, HT=10 sec and UT=10 sec when the metal loss(Mo) is 3.5 mm. Acoustic Emission(AE) technique was applied to analyze the dissimilar friction welding of Alloy718 and SCM440. The relationship between the AE parameters and dissimilar friction welding of both material was discussed. In the case of heating time of 6 sec, 10 sec, 14 sec and 20 sec, 5 AE events per 0.5 seconds and energy about $2.7{\times}10^{10}$ were exhibited in heating time. In upsetting time, resulting in various numbers of events per second and very low energy. The frequency range of the signal generated during the heating time was about 200 kHz. However, the upsetting time resulted in a wide range of signals from very low frequency to high frequency of 500 kHz due to rapid plasticity of the material.

• Journal of Powder Materials
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• v.31 no.1
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• pp.37-42
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• 2024

Friction stir spot welding (FSSW) is a solid-state joining process and a rapidly growing dissimilar material welding technology for joining metallic alloys in the automotive industry. Welding tool shape and process conditions must be appropriately controlled to obtain high bonding characteristics. In this study, FSSW is performed on dissimilar materials AA5052-H32 aluminum alloy sheet and SPRC440 steel sheet, and the influence of the shape of joining tool and tool insertion depth during joining is investigated. A new intermetallic compound is produced at the aluminum and steel sheets joint. When the insertion depth of the tool is insufficient, the intermetallic compound between the two sheets did not form uniformly. As the insertion depth increased, the intermetallic compound layer become uniform and continuous. The joint specimen shows higher values of tensile shear load as the diameter and insertion depth of the tool increase. This shows that the uniform formation of the intermetallic compound strengthens the bonding force between the joining specimens and increases the tensile shear load.

• International Journal of Precision Engineering and Manufacturing
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• v.3 no.2
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• pp.33-44
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• 2002

The problem of eigenvalues and eigenvectors is obtained from a v-notched crack in pseudo-isotropic dissimilar materials by the traction free boundary and the perfect bonded conditions at interface. The complex stress function of the two-term William's type is used. The eigenvalues are solved by a commercial numerical program, MATHEMATICA. Stress singularities for v-notched cracks in pseudo-isotropic dissimilar materials are discussed. The RWCIM(Reciprocal Work Contour Integral Method) is applied to the determination of eigenvector coefficients associated with eigenvalues with egenvalues. The RWCIM algorithm is also coded by the MATHEMATICA.