• Journal of the Korean Society for Railway
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• v.14 no.2
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• pp.94-99
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• 2011

In this study, the stress reduction effect was evaluated for GFRP/Mg single lap bonded joints according to six different adherend shapes. Six different types of the single lap joint specimen were modeled and assessed using geometrically nonlinear finite element analysis. Moreover, three dimensional effect of stress distribution for the different adherend shapes was investigated. From the analysis, the dissimilar single lap bonded joint with the normal tapering and without the spew fillet (model 2) showed the highest stress values. In contrast, the peel stress values of both the square ended adherends with the spew fillet (model 3) and the reverse tapered adherends with the spew fillet (model 5) were 65.8% and 65.5% lower than the reference model.

• Steel and Composite Structures
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• v.17 no.6
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• pp.851-865
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• 2014

Full penetration welded steel moment-resisting frame (SMRF) structures with welded box sections are widely employed in steel bridges, where a large number of steel bridges have been in operation for over fifty years in Japan. Welding defects such as incomplete penetration at the beam-column connections of these existing SMRF steel bridge piers were observed during inspection. Previous experiments conducted by the authors' team indicate that gusset stiffeners (termed fillets in this study) at the beam-web-to-column-web joint of the beam-column connections may play an important role on the seismic performance of the connections. This paper aims to experimentally study the effect of the fillet radius on seismic performance of the connections with large welding defects. Four specimens with different sizes of fillet radii were loaded under quasi-static incremental cyclic loading, where different load-displacement relations and cracking behaviors were observed. The experimental results show that, as the size of the fillet radius increases, the seismic performance of the connections can be greatly improved.

• Journal of Welding and Joining
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• v.34 no.4
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• pp.48-54
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• 2016

The use of Zn coated steel has increased in the automotive industry due to its excellent corrosion resistance. Conventionally the BIW(body-in-white) structure and the hang-on parts have been made of Zn coated steel and more recently Zn coated steel began to be applied in the chassis parts. During gas metal arc (GMA) welding of the chassis part, lap fillet joint used to be adopted but spatter generation and porosities are most important concerns. In the industrial applications, an intentional joint gap was made to avoid the weld defects but it is not easy to control the size of joint gap. In this research, gas tungsten arc (GTA) is combined with GMA welding where GTA precedes GMA. As pulsed arc was adopted as GMA, GTA was oscillated along the longitudinal direction by pulsing GMA, but the arc oscillation did not disturb the molten droplet transfer of GMA welding. By increasing the distance between GTA and GMA, the length of weld pool increased and porosity could be reduced. Moreover porosity in the welds was fully removed when the distance between two arcs was 15 mm.

• Journal of Welding and Joining
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• v.28 no.2
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• pp.84-90
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• 2010

Fillet welding accounts for about 80% of all constructing process of ship and ocean structure. T-joint is one of the typical shapes which are frequently reported to experience the fatigue damage when the marine structure meets the storm loads. The fatigue damage is affected by the magnitude of residual stresses on the weld. Recently, many shipping registers and design guidances have required that the fatigue strength assessment method should be compensated by the effect of the residual stress in case that the random loading or storm loading is applied to the marine vessels. This study suggests the computational procedure to analyze the residual stresses of T-joint specimen that is frequently reported to get damaged by the storm loading. Experiment by XRD as well as the 3-D computational welding model is presented in order to get the profile of residual stress. Throughout the comparison of experimental result with the computational result, the computational model was validated. Thereafter, characteristics of he residual stresses in the joint are discussed.

• Journal of Ocean Engineering and Technology
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• v.18 no.6 s.61
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• pp.79-83
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• 2004

The curved blocks which compose the bow and stem of a ship contain many skewed joints that are inclined horizontally and vertically. Most of these joints have a large fitness error and are continuously changing their form and are not easily accessible. The welding position and parameter values should be appropriately set in correspondence to the shape and the inclination of the joints. The welding parameters such as current, voltage, travel speed, and melting rate, are related to each other and their values must be in a specific limited range for the sound welding. These correlations and the ranges are dependent up on the kind and size of wire, shielding gas, joint shape and fitness. To determine these relationships, extensive welding experiments were performed. The experimental data were processed using several information processing technologies. The regression method was used to determine the relationship between current voltage, and deposition rate. When a joint is inclined, the weld bead should be confined to a the limited size, inorder to avoid undercut as well as overlap due to flowing down of molten metal by gravity. The dependency of the limited weld size which is defined as the critical deposited area on various factors such as the horizontally and vertically inclined angle of the joint, skewed angle of the joint, up or down welding direction and weaving was investigated through a number of welding experiments. On the basis of this result, an ANN system was developed to estimate the critical deposited area. The ANN system consists of a 4 layer structure and uses an error back propagation learning algorithm. The estimated values of the ANN were validated using experimental values.

• 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.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.178-180
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• 2006

• Proceedings of the KWS Conference
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• 2005.11a
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• pp.49-51
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• 2005

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.5
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• pp.561-565
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• 2010

Stainless steel sheets are widely used as structural materials for the manufacture of railroad cars and commercial vehicles. These kinds structures used stainless steel sheets are commonly fabricated by using the gas welding. For the fatigue design of gas welded joints such as fillet joints and plug joints, it is necessary to obtain information on the stress distribution at the weldment and the fatigue strength of the gas welded joints. Moreover the influence of the geometrical parameters corresponding to the gas welded joints on the stress distribution and fatigue strength must be evaluated. ${\Delta}P-N_f$ curves were obtained from the data recorded in fatigue tests. Using these results, the ${\Delta}P-N_f$ curves were rearranged according the relation between $\Delta\sigma-N_f$ and the maximum stress at the edge of the fillet welded joint.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.3
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• pp.220-226
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• 2003

This paper presents the result of an investigation on the application of the acoustic emission method to the monitoring of fatigue crack initiation, growth and track location in welded joints. Fatigue test was carried out for a typical fillet welded joint of ship structure. AE parameter such as ring down count was analyzed in time domain and crack locations were examined by source location and cluster option which is one of the functions of AE signal processor The usability of AE mettled was confirmed for the detection of the initiation and location of through crack.