• Journal of Welding and Joining
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• v.20 no.6
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• pp.802-808
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• 2002

Front-side members are structures with the greatest energy absorbing capability in a front-end collision of vehicles. This paper was performed to analyze initial collapse characteristics of spot welded hat and double hat-shaped section members, which are basic shape of side members, on the shift of flange weld pitches. The impact collapse tests were carried out by using home-made vertical air compression impact testing machine, and impact velocity of hat-shaped section members is 4.17m/sec and that of double hat-shaped section members is 6.54m/sec. In impact collapse tests, the collapsed length of hat-shaped section members was about 45mm and that of double hat-shaped section members was about 50mm. In consideration of these condition, axial static collapse tests(0.00017m/sec) of hat and double hat-shaped section members were carried out by using UTM which was limited displacement, about 50mm. As the experimental results, to obtain the best initial collapse characteristics, it is important that stiffness of vehicle members increases as section shapes change and the progressively folding mode induces by flange welding pitch.

• Journal of Welding and Joining
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• v.21 no.1
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• pp.54-59
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• 2003

In the present work, a formula for plate deformation produced by line heating, in terms of process parameters such as heat input and plate dimensions, is developed analytically using an eigenstrain concept. The residual deformation that was due to thermal process was depends on the magnitude and region of plastic strains at heating zone. The magnitude of plastic strains was determined by disk model and its region was calculated using the Rosenthal"s solution. The vertical displacement of the plate was analyzed by using an infinite laminated plate theory to consider a cuboidal inclusion with an eigenstrain. Comparison of the calculated results and experimental data shows the accuracy and validity of proposed method.thod.

• Journal of Welding and Joining
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• v.16 no.6
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• pp.77-85
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• 1998

Effects of non-cleaning and cleaning fluxes on the wetting properties and defects at flow soldered joints were investigated. Non-cleaning flux (R-type of 3.3% solid content) and cleaning flux (RMA-type of 15% solid content) were used. Wetting test was accomplished by wetting balance method with changing surface state of wetting specimen, CU. Sn-37%Pb solder was used for wetting test and flow soldering. As experimental results, the wetting time for vertical force from the surface tension being zero was mainly affected by surface state of the wetting specimen. Non-cleaning flux had a good wettability compared with cleaning flux. In case of non-cleaning flux, conveyor speed had a great affection to defects of bridge, icicle, and poor solder.

• Journal of Welding and Joining
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• v.21 no.4
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• pp.31-38
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• 2003

Line heating is an effective and economical process for forming flat metal plates into three-dimensional shapes for plating of ships. Because the nature of the line heating process is a transient thermal process, followed by a thermo elastic plastic stress field, predicting deformed shapes of plate is very difficult and complex problem. In this paper, neural network model o3r solving the inverse problem of metal forming is proposed. The backpropagation neural network systems for determining line-heating positions from object shape of plate are reported in this paper. Two cases of the network are constructed-the first case has 18 lines which have different positions and directions and the second case has 10 parallel heating lines. The input data are vertical displacements of plate and the output data are selected heating lines. The train sets of neural network are obtained by using an analytical solution that predicts plate deformations in line heating process. This method shows the feasibility that the neural network can be used to determine the heating-line positions in line heating process.

• Journal of Welding and Joining
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• v.21 no.4
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• pp.87-91
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• 2003

Effects of the circular and non-circular pad shapes on self-alignment in BGA soldering are predicted using Surface Evolver, and the calculated results are compared with experimental data. While the pad shape has minor effects on self-alignment in the vertical direction, self-alignment in the lateral direction depends on the pad direction and length ratio of the non-circular pad. Larger restoring force is obtained in the minor-axis direction than the major-axis direction, which suggests a possibility of reducing misalignment in the specific direction. The restoring force of the circular pad is between those of the non-circular pad in the major and minor-axis directions. The calculated results of Surface Evolver show reasonably good agreements with experimental data using the shear loading system.

• Journal of Welding and Joining
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• v.17 no.6
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• pp.100-107
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• 1999

In this paper, we deal with the speckle noise reduction and parameter estimation of ultrasonic NDT(non-destructive test) signals obtained during weld inspection of piping. The overall approach consists of three major steps, namely, speckle noise analysis, proposition of wavelet domain AR(autoregressive) model and flaw detection by proposed model parameter. The data are first processed whereby signals obtained using vertical and angle beam transducer. Correlation properties of speckle noise are then analyzed using multiresolution analysis in wavelet domain. The parameter estimation curve obtained using the proposed model is classified a flaw in weld region where is contaminated by severe speckle noise and also clear flaw signal is obtained through CA-CFAR threshold estimator that is a nonlinear post-processing method for removing the noise from reconstructed ultrasonic signal.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.5
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• pp.833-847
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• 2015

Although the transverse butt weld method with ceramic backing strip has been widely used in various industrial fields for its fabricational convenience, it is rarely used in offshore industries since the fatigue strength of the weld joint has not been proved sufficiently. This study conducted fatigue tests for series of butt weld specimens with horizontal (2G) and vertical (3G) welding positions in order to verify the fatigue strength compared to S-N curve by DNV (Det Norske Veritas), IIW (International Institute of Welding) and Eurocode 3. The difference of the 2G specimens and the 3G specimens are investigated in terms of angular distortion and the effect on the fatigue strength are analyzed.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1604-1612
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• 2009

This study introduces comparison the testing results of the AL car body which is applied to FSW and GMAW welding method. The car body is made of aluminum structure materials like a sandwich panel. The static load test was performed to evaluate the structural characteristic and stability of the AL car body. Considering the vertical, compressive, twisting load and 3-point supporting, Bend natural frequency Measurement, Twist natural frequency Measurement type as a testing terms, the structural stability of a car body was evaluated.

• Journal of Welding and Joining
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• v.16 no.4
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• pp.109-116
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• 1998

The three-dimensional profile of a solder fillet is predicted by minimizing the surface tension and gravity energies of the solder joint using finite element modeling. Geometric complexity stemming from the inclined plane of the gullwing lead is resolved by employing three element types. These element types are used to describe the joint profile formed on the vertical, inclined and interfacial planes. The predicted solder joint profiles show good agreements with the experimental data provided that the solder volume is adjusted considering the wicking effects. Effects of the pad length, inclined lead angle and solder volume on joint profiles are also investigated.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.52-55
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• 1997

This paper discusses an automatic visual-servoing system, in which a laser and a CCD camera are used for imaging the pattern of joint groove. The algorithm used here is simple and robust to find out the gap width and gap center. As a consequence, the speed of algorithm is very fast and optimized. A feature of this system is that it processes only by summing the vertical line and horizontal line of screen without any image preprocessing in order to get the energy information of lines alternatively. It is practical and useful for the system requiring a fast process time of vision.