• Proceedings of the KWS Conference
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• 1994.10a
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• pp.44-44
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• 1994

• Proceedings of the KWS Conference
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• 2002.05a
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• pp.158-160
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• 2002

• Proceedings of the KWS Conference
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• 2001.05a
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• pp.153-156
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• 2001

• Proceedings of the KWS Conference
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• 2001.05a
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• pp.157-160
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• 2001

• Proceedings of the KWS Conference
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• 2001.10a
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• pp.277-280
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• 2001

• Journal of Welding and Joining
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• v.4 no.1
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• pp.40-46
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• 1986

This investigation studied the toughness variations in the narrow gap weldment with the notch location. Specimens with the notch at the center of the weld metal showed the lowest toughness. As the location of notchmoves to fusion line, the impact properties improve reaching a maximum at the fusion boundaries. This improvement in toughness can be explained by the microstructural feature showing in the narrow gap weldment. "one pass/layer" technique performed in narrow gap welding results in the increased proportion of refined structure as approaching to fusion boundary from weld center and thus leave 100% refined structure along the fusion boundary. HAZ also shows 100% refined structure with respect to base metal structure accompanied with the significant suppression of ductile-brittle transition temperature.mperature.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.10a
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• pp.238-246
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• 2001

Residual stresses and thermal deformation of a structure due to welding are very imfortant factors for a weld design. It has been carried therretical analysis to invesitigate influence of heat flux to residual stresses and thermal deformation producted by curcumferential welding. Temperature,stresses and deformationn are obtain as a function of circumferentisl drgree and distance from welding center line. These result can applicate to predict and remove the deformation or residual stresses built up by welding.

• Steel and Composite Structures
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• v.19 no.3
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• pp.569-583
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• 2015

Recent years, explosive welding structures have been widely used in many engineering fields. The bonding state detection of explosive welding structures is significant to prevent unscheduled failures and even catastrophic accidents. However, this task still faces challenges due to the complexity of the bonding interface. In this paper, a new method called dual-tree complex wavelet transform based permutation entropy (DTCWT-PE) is proposed to detect bonding state of such structures. Benefiting from the complex analytical wavelet function, the dual-tree complex wavelet transform (DTCWT) has better shift invariance and reduced spectral aliasing compared with the traditional wavelet transform. All those characters are good for characterizing the vibration response signals. Furthermore, as a statistical measure, permutation entropy (PE) quantifies the complexity of non-stationary signals through phase space reconstruction, and thus it can be used as a viable tool to detect the change of bonding state. In order to more accurate identification and detection of bonding state, PE values derived from DTCWT coefficients are proposed to extract the state information from the vibration response signal of explosive welding structure, and then the extracted PE values serve as input vectors of support vector machine (SVM) to identify the bonding state of the structure. The experiments on bonding state detection of explosive welding pipes are presented to illustrate the feasibility and effectiveness of the proposed method.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.60-64
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• 2008

According to previous research, welding-induced stress in steel structures can significantly affect the fatigue behaviour; it produces initial damage of weldiug part of structure locally and residual stresses reduce the fatigue strength after welding precess. In this study, through continuum damage mechanics, we can estimate the weldiug damage using the stress and strain history during welding process and the effect of welding residual stress for assessment of fatigue life. The variation of welding-induced stresses and strains need be traced precisely in advance for a reliable weldiug damage assessment. In this study, a damage and fatigue analysis techniques for steel structures with welding-induced residual stress are presented. First, We calculate the history of temperature according with welding process. And residual stress with a welding thermal history was evaluated by non-linear thermal stress analysis. Secondly, welding damage and fatigue life are estimated with kinetic damage law.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.5
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• pp.31-38
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• 2016

This study proposes an optimal design for a robotic welding system for a high-strength steel armor plate. In order to identify the welding defect parameters, we analyzed the 4M (man, machine, materials, method) characteristics diagram, as well as a cause and effect matrix, to improve the productivity and quality of welding defects. From these analyses, we designed optimal welding conditions and carried out welding tests -- such as mechanical testing and macro structure tests - with positive results. We determined that it was possible to obtain a quality similar to manual welding with our robotic welding system. In the future, we expect that the system will be used as inspiration for future welding system designs.