• Journal of Ocean Engineering and Technology
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• v.23 no.2
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• pp.87-91
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• 2009

The welding distortion of a hull structure in the shipbuilding industry is inevitable at each assembly stage. The geometric inaccuracy caused by welding distortion tends to preclude the introduction of automation and mechanization and requires additional man-hours for adjustment work during the following assembly stage. To overcome this problem, a distortion control method should be applied. For this purpose, it is necessary to develop an accurate prediction method that can explicitly account for the influence of various factors on the welding distortion. The validity of this prediction method must also be clarified through experiments. For the purpose of reducing the weld-induced bending deflection, this paper proposes the plastic counter-deforming method (PCDM), which uses line heating as the optimum distortion control method. The validity of this method was substantiated by a number of numerical simulations and actual measurements.

• Journal of Welding and Joining
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• v.21 no.4
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• pp.75-79
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• 2003

The welding distortion of a hull structure in the shipbuilding industry is inevitable at each assembly stage. This geometric inaccuracy caused by the welding distortion tends to preclude the introduction of automation and mechanization and needs the additional man-hours for the adjusting work at the following assembly stage. To overcome this problem, a distortion control method should be applied. For this purpose, it is necessary to develop an accurate prediction method which can explicitly account for the influence of various factors on the welding distortion. The validity of the prediction method must be also clarified through experiments. For the purpose of reducing the weld-induced bending deflection, this paper proposes the plastic counter-deforming method (PCDM) using the line heating as the optimum distortion control method. The validity of this method has been substantiated by a number of numerical simulations and actual measurements.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.700-705
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• 2002

The welding distortion of a hull structure in the shipbuilding industry is inevitable at each assembly stage. The geometric inaccuracy caused by the distortion tends to preclude the introduction of automation and mechanization and needs the additional man-hours for the adjusting work at the following assembly stage. To overcome this problem, a distortion control method should be applied. For this purpose, it is necessary to develop an accurate prediction method which can explicitly account for the influence of various factors on the welding distortion. In order to minimize the weld-induced angular distortion in thick weldments, this paper proposes the optimum groove design for various plate thicknesses as the distortion control method. The validity of this method has been substantiated by a number of numerical simulations and experiments.

• Journal of Ocean Engineering and Technology
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• v.17 no.3 s.52
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• pp.27-32
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• 2003

The welding distortion of a hull structure in the shipbuilding industry is inevitable at each assembly stage. The geometric inaccuracy caused by the distortion tends to preclude the introduction of automation and mechanization. Thus, additional man-hours are needed for the adjusting work in the assembly stage. To overcome this problem, a distortion control method should be applied. For this purpose, it is necessary to develop an accurate prediction method that can explicitly account for the influence of various factors on the welding distortion. In order to minimize the weld-induced residual deformation, this paper proposes the optimum welding sequence as a method for distortion control. The validity of this method has been substantiated by a number of numerical simulations and experiments.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.1 s.145
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• pp.68-74
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• 2006

The welding distortion of a hull structure in the shipbuilding industry is inevitable at each assembly stage. This geometric inaccuracy caused by the welding distortion tends to preclude the introduction of automation and mechanization and needs the additional man-hours for the adjusting work at the following assembly stage. To overcome this problem, a distortion control method should be applied. For this purpose, it is necessary to develop an accurate prediction method which can explicitly account for the influence of various factors on the welding distortion. The validity of the prediction method must be also clarified through experiments. For the purpose of reducing the weld-induced bending deflection, this paper proposes the mechanical tensioning method (MTM) as the optimum distortion control method. The validity of this method has been substantiated by a number of numerical simulations and actual measurements.

• Journal of Ocean Engineering and Technology
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• v.22 no.6
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• pp.95-99
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• 2008

The block assembly of ship consists of a certain type of heat processes such as cutting, bending welding residual stress relaxation and fairing. The residual deformation due to welding is inevitable at each assembly stage. The geometric inaccuracy caused by the welding deformation tends to preclude the introduction of automation and mechanization and needs the additional man-hours for the adjusting work at the following assembly stage. To overcome this problem, a distortion control method should be applied. For this purpose, it is necessary to develop an accurate prediction method which can explicitly account for the influence of various factors on the welding deformation. The validity of the prediction method must be also clarified through experiments. This paper proposes a simplified analysis method to predict the welding deformation of panel block structure. For this purpose, a simple prediction model for fillet welding deformations has been derived based on numerical and experimental results through the regression analysis. On the basis of these results, the simplified analysis method has been applied to some examples to show its validity.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.2
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• pp.49-56
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• 2003

The welding deformation of a hull structure in the shipbuilding industry is Inevitable at each assembly stage. The geometric inaccuracy caused by the welding deformation tends to preclude the introduction of automation and mechanization and needs the additional man-hours for the adjusting work at the following assembly stage. To overcome this problem, a distortion control method should be applied. For this purpose, it is necessary to develop an accurateprediction method which can explicitly account for the influence of various factors on the welding deformation. The validity of the prediction method must be also clarified through experiments. This paper is aimed at deriving the simple prediction model for fillet welding deformations. For this purpose, the thermal elasto-plastic analysis varying the welding conditions and plate thickness has been performed. On the basis of numerical results, the formulae for angular distortion and transverse shrinkage have been derived through the regression analysis. Experimental work has been also carried out to clarify the validity of numerical results. It has been found that the numerical results show a good agreement with those of experiments

• Journal of the Society of Naval Architects of Korea
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• v.41 no.2
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• pp.106-113
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• 2004

The block assembly of ship consists of a certain type of heat processes such as cutting, bending, welding, residual stress relaxation and fairing. The residual deformation due to welding is inevitable at each assembly stage. The geometric inaccuracy caused by the welding deformation tends to preclude the introduction of automation and mechanization and needs the additional man-hours for the adjusting work at the following assembly stage. To overcome this problem, a distortion control method should be applied. For this purpose, it is necessary to develop an accurate prediction method which can explicitly account for the influence of various factors on the welding deformation. Systematic and quantitative theoretical works to clarify the effects of various factors on the welding deformation have rarely been found. Therefore, in this paper, the effects of various factors, such as welding process and gravity on the butt welding deformation have been investigated through a number of numerical analyses. In addition, this paper proposes a simplified analysis method to predict the butt welding deformation in actual plate structure. For this purpose, a simple prediction model for butt welding deformations has been derived based on numerical and experimental results through the regression analysis. Based on these results, the simplified analysis method has been applied to some examples to show its validity.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.2
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• pp.57-62
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• 2003

The block assembly of ship consists of a certain type of heat processes such as cutting, bending, welding, residual stress relaxation and fairing. The residual deformation due to welding is inevitable at each assembly stage. The geometric inaccuracy caused by the welding deformation tends to preclude the introduction of automation and mechanization and needs the additional man-hours for the adjusting work at the following assembly stage. To overcome this problem, a distortion control method should be applied. For this purpose, it is necessary to develop an accurate prediction method which can explicitly account for the influence of various factors on the welding deformation. The validity of the prediction method must be also clarified through experiments. This paper proposes a simplified analysis method to predict the welding deformation of panel block structure. For this purpose, a simple prediction model for fillet welding deformations has been derived based on numerical and experimental results through the regression analysis. On the basis of these results, the simplified analysis method has been applied to some examples to show its validity.

• Structural Engineering and Mechanics
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• v.16 no.3
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• pp.361-369
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• 2003

In this paper, the structural behavior of R/C cylindrical panel is analyzed by experimental results. To avoid the geometric imperfection, R/C shell specimens are made by use of a stiff steel mold. From experimental results, the load carrying behavior of R/C cylindrical panel is presented under an external lateral pressure. Even if R/C shell does not posses geometric imperfections, the inaccuracy of the reinforcement position strongly affects to the ultimate strength and the failure patterns of such shells. To explain these effects, FEM nonlinear analyses are done under the same conditions as those of experiments. The behavior of R/C cylindrical shells are well simulated under the consideration of both the geometric imperfection and several inaccuracies.