• Proceedings of the KWS Conference
• /
• 2003.05a
• /
• pp.275-277
• /
• 2003

• Proceedings of the KWS Conference
• /
• 2001.10a
• /
• pp.7-10
• /
• 2001

• Journal of the Society of Naval Architects of Korea
• /
• v.47 no.3
• /
• pp.430-437
• /
• 2010

In this paper, we develop a shape design optimization method for thermo-elastoplasticity problems that is applicable to the welding or thermal deformation problems of ship structures. Shell elements and a programming language APDL in a commercial finite element analysis code, ANSYS, are employed in the shape optimization. The point of developed method is to determine the design parameters such that the deformed shape after welding fits very well to a desired design. The geometric parameters of surfaces are selected as the design parameters. The modified method of feasible direction (MMFD) and finite difference sensitivity are used for the optimization algorithm. Two numerical examples demonstrate that the developed shape design method is applicable to existing hull structures and effective for the structural design of ships.

• Proceedings of the KWS Conference
• /
• 2003.05a
• /
• pp.172-175
• /
• 2003

A genetic algorithm was applied to an arc welding process to determine near optimal settings of welding process parameters which produce good weld quality. It has an advantage of being able to find optimal conditions with a fewer number of experiments than conventional full factorial design. According to the conventional full factorial design, in order to find the optimal welding conditions, 16,384 experiments must be performed. The genetic algorithm however, found the near optimal welding conditions from less than 60 experiments.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.1322-1327
• /
• 2007

Many automotive companies have tried to apply the aluminum alloy sheet to car body because reducing the car weight can improve the fuel efficiency of vehicle. In order to do that, sheet materials require of weldablity, formability, productivity and so on. Aluminum alloy was not easy to join these metals due to its material properties. Thus, the laser is good heat source for aluminum alloy welding because of its high heat intensity. However, the welding quality was not good by porosity, underfill, and magnesium loss in welded metal for AA5182 aluminum alloy. In this study, Nd:YAG laser welding of AA 5182 with filler wire AA 5356 was carried out to overcome this problem. The weldability of AA5182 laser welding with AA5356 filler wire was investigated in terms of tensile strength and Erichsen ratio. For full penetration, mechanical properties were improved by filler wire. In order to optimize the process parameters, model to estimate tensile strength by artificial neural network was developed and fitness function was defined in consideration of weldability and productivity. Genetic algorithm was used to search the optimal point of laser power, welding speed, and wire feed rate.

• Journal of Advanced Marine Engineering and Technology
• /
• v.32 no.2
• /
• pp.306-314
• /
• 2008

General metal welding occurs distortion. Also, reducing distortion is required much cost. Therefore, the purpose of this study is optimization of welding conditions to reduce distortion in welding of monolithic rack housing for modular steering gear. Firstly, heat source for welding was chosen arc and laser. Secondly, it investigated optimizing welding conditions in bead welding by arc and laser heat source, and welding conditions in fillet welding was optimized with welding shapes. Finally, it was measured temperature distribution of welds by infrared camera and angle distortion in fillet welding. As a result, laser welding was superior to arc welding on distortion.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.679-682
• /
• 2002

Resistance spot welding using air gun has been used for joining the sheet metal in automotive manufacturing process. Although air gun has many advantages, it also has the limitation to control the pressure as a factor to improve weld quality. In this study, we apply servo gun using servo motor to resistance spot welding and find the relationship between welding pressure and welding quality. Trough the experiment to change welding pressure during the welding cycle, we can make it clear that the change of welding pressure is greatly influence on the welding quality. To get in a. using response surface methodology, drew out the optimal welding pressure profile for welding quality progresses. We made an optimal profile of welding pressure which improves welding quality using response surface methodology.

• Journal of Welding and Joining
• /
• v.29 no.6
• /
• pp.45-48
• /
• 2011

In this research, laser welding of automotive transmission components was investigated to replace electron beam welding which is normally conducted under vacuum condition. Fiber laser welding was applied to the automotive transmission components - hub clutch and annulus gear. In the component welding, the laser welding parameters were optimized to eliminate spatters and the end crater. By applying laser welding to the transmission parts, the process time could be reduced up to 70% compared with the current electron beam welding process.

• Proceedings of the KWS Conference
• /
• 2004.05a
• /
• pp.209-211
• /
• 2004

자동차 차체의 조립공정에서 주로 사이리스터 방식의 저항 점 용접기를 이용해 용접을 하고 있으나, 최근에는 인버터방식을 이용하려는 시도가 진행되고 있다. (중략)

• Journal of Welding and Joining
• /
• v.26 no.1
• /
• pp.63-68
• /
• 2008

This paper has aimed to prevent excessive heat input by controlling arc distribution and heat input capacity with pulse GTAW in order to improve weld quality in 0.08mm pressure gauge diaphragm and flange welding parts. A design of experiment was designed using Box-Behnken method to optimize a welding process. The pulse GTAW parameters such as pulse current, base current, pulse duty, frequency and welding speed were set to input variables while hydraulic pressure that represents welding characteristics in diaphragm and flange joint were set to output variables. Based on the test result, a second regression equation was obtained between input and output variables and turned out significant. Besides, an influence of parameters has been confirmed through response surface analysis using the second-order regression equation and optimum welding condition was obtained through a grid-search method. The optimum welding condition was set to pulse current 84.4(A), base current 29.6(A), pulse duty 58.8(%), frequency 10(%), and welding speed 596(mm/min). Then, decent bead shape was acquired with no excessive heat input under the $2.3kgf/cm^2$ of hydrostatic pressure.