• Journal of Welding and Joining
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• 제20권1호
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• pp.55-61
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• 2002

The automobile is made up of about twenty thousand parts. Some parts are formed by pressing and combined by spot welding. Among them, steel palate of fuel tank is formed in the metal mold and bending parts are jointed by spot and seam welding. To find weldability conditions of spot welding, clearance between two welding steel plates was made and after spot welding, weldability is evaluated by means of tensile shear load, nugget size and shape. Specimen used in this study was a mild steel of 1.2mm thickness and electrode was Cu-Cr alloy of 6mm diameter. When spot welding started, the clearance of two steel plates was changed 0mm, 3mm and 5mm step by step. The fractured surface of specimen after this test was observed by Optical Microscope to measure microstructure and nugget shape. When clearance of two specimen was 3mm and 5mm, strength and nugget size was decreased and nugget shape was not clear.

• Journal of Welding and Joining
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• 제29권6호
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• pp.82-87
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• 2011

In this study, we conducted laser welding by using remote scanner that is 5J32 aluminum alloy to observe the mechanical properties and optimize welding process parameters. As the control factors, laser incident angle, laser power and welding speed were set and as the result of weldablility, tensile shear tests were performed. ANOVA (Analysis of Variation) was also carried out to identify the influence of process variables on tensile shear strength. Strength estimation models were suggested using regression alnalysis and 2nd order polynomial model had the best estimation performance. In addition optimal welding condition was determined in terms with wedalility and productivity using objective function and fitness function. Final optimized welding condition was laser power was 4 kW, and welding speed was 4.6 m/min.

• 한국구조물진단유지관리공학회 논문집
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• 제5권4호
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• pp.131-138
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• 2001

In inverted T-shape composite beam examine the structural behavior by experiment According to arrangement, type of stud connector, type of shear connector, reinforcement by welding of stirrup and a close analysis we came to these conclusion. 1) The compare result of bending strength according to arrange type of stud connector : A1-W(stud connector located web)specimen is exceed than A1-F(stud connector located flange). 2) B1-N(using prominence and depression of the web by shear connector) specimen is decrease than A1-W(using stud bolt by shear connector)specimen in bending strength and B2-N(reinforced by welding the stirrup to lower flange)specimen is similar with A2-W specimen. 3) According to reinforced by welding the stirrup to flange, the stiffness and bending strength of the beams are increase. A-scries stirrup comparatively low effective in the increase of strength by welding the stirrup to flange because enough composite effect show by stud connector, but B-series stirrup is comparatively high effective in shear connector effect because shortage of prominence and depression of the web.

• Journal of Welding and Joining
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• 제17권1호
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• pp.82-87
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• 1999

The basic remote sleeve repair-welding technology by the pulsed Nd:YAG laser for increasing the lifetime of the steam generator tube in a nuclear power plant has been developed. The relationship between the connection width and welding parameters have been investigated for the fundamental research to apply the sleeve-repair-welding technique to the nuclear industry. The Inconel 600 tube and Inconel 690 sleeve used for high temperature and high pressure service were welded as round lap welding by Nd:YAG laser. It was observed that the tensile shear strength, 340MPa of the welded specimen is equivalent to about 60% of that of the base metal (Inconel 600), 550MPa. The difference between the hardness of the base metal and that of the laser welds was about 10%. Ductile fracture was partly occurred in the weld but the cracking has not been observed. In spite of absence of the crack, the strength of welds was not sufficient in terms of the tensile shear strength.

• Journal of Welding and Joining
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• 제24권3호
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• pp.55-59
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• 2006

This paper is concerned with a study on cyclic bending load of bus folding door pillar including adhesive bonding and spot welding. Three specimen types were used such as spot welding, I-type adhesive bonding and M-type adhesive bonding in this study. The tensile-shear tests were carried out to evaluate the tensile-shear strength of these three specimen types. Also four-point bending tests were carried out to evaluate the static and dynamic bending load. From the results, using adhesive bonding has a better effect on the static and dynamic bending load than using spot welding. Therefore, manufacturing better structural products can be expected by applying hybrid welding using adhesive and spot welding to those.

• Steel and Composite Structures
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• 제18권2호
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• pp.345-355
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• 2015

In this study, the effects of weld parameters on nugget size and tensile-shear strength of welding joint in electrical resistance spot welding of galvanized DP 600 steel sheets having 1.2 mm were investigated. Taguchi design method has been employed to examine the effects of five parameters of welding current, electrode pressure, welding time, clamping time and holding time by using the $L_{27}(5^3)$ orthogonal array. Results showed that the most effective parameters on tensile shear strength and the nugget size ratio (hn/dn) were found as welding current and welding time, whereas electrode pressure, clamping time and holding time were less effective factors. Max. 545 MPa strength was obtained through proposed optimum conditions by Taguchi technique.

• KIEAE Journal
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• 제12권5호
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• pp.93-98
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• 2012

The headed studs those are used extensively for steel-composite construction is specified as SS400 at the current Korean Standard specification considering the welding condition. And the corresponding equation for the shear force calculation is limited for the use of compression strength of concrete below $300kg/cm^2$. However, it is expected that the high strengthening and precast of both steel and concrete due to the necessity of shear connector or other connecting material for the combination of steel and concrete. Therefore, the experimental results obtained during the development process of high strength stud for the connection of high strength concrete and the steel member are reported in this paper. Also the effectiveness of newly developed shear connector using pipe to increase the stiffness of a stud is verified by comparing both the stiffness and the strength with common stud bolt through the welding ability, mechanical characteristics and experimental investigation.

• Journal of Welding and Joining
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• 제13권2호
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• pp.106-114
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• 1995

The characteristics of adhesive bonded joint of steels for automobile were investigated. Shear and tear strength were tested and analyzed for the joints of cold rolled steel sheets bonded with three kinds of epoxy and urethane based adhesive. The results showed that the tensile shear strength and the tear strength of adhesive joint were affected by the shape of adhesive joint such as the length and width of adhesive joint. The thickness of adhesive layer was very important factor affecting the bonding strength. The shear strength increased with decrease of the thickness of adhesive layer, while the tear strength decreased as the thickness of adhesive layer decreased. In comparison with the strength of spot welded joint, the shear strength of adhesive Joint was higher than that of spot welded joint, but the tear strength of adhesive Joint was lower than that of spot welded joint.

• International Journal of Advanced Culture Technology
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• 제3권1호
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• pp.161-168
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• 2015

This article aims to apply a friction stir spot welding for producing a lap joint of AA1100 aluminum alloy and SGACD zinc coated steel. The experiment was designed by MINITAB and then investigated the relation among the friction spot joint parameters. The experimental results are as follows. The friction spot joining could successively produce the lap joint of AA1100 aluminum alloy and SGACD zinc coated steel. Interaction between the rotate speed, the hold time and the tool insert speed affected to vary the tensile shear strength of the lap joint. The prediction of the optimized welding parameters that indicated the tensile shear strength of 1966 N was the rotated speed of 4000 rpm, the pin hold time of 6 sec, the pin insert rate of 6 mm/min with the S/N ratio of 66.56 that was higher than that of the total mean S/N ratio. The practical experiment of the predicted welding parameters indicated the tensile shear strength of 2165 N and had the S/N ratio of 66.70 that was higher than the predicted tensile shear strength.

• Journal of Welding and Joining
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• 제10권1호
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• pp.52-59
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• 1992

Resistance spot weldability of cold rolled 80kg/mm$^{2}$ and 45kg/mm$^{2}$ grade high strength steel sheets for automobile structure was investigated focussing on the influences of welding parameters such as welding current and welding time on the weld strength and the nugget formation. The results of this study showed that the optimum ranges of welding current for the grade 80 and grade 45 were 5.0 cycle(250 m sec.) It was also shown that the tensile shear strength of the resistance spot weld was strongly influenced by both current and time applied in welding procedure, however, the tensile shear strength was mainly affected by welding time for the higher strength steel.