• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.1
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• pp.38-44
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• 2003

In this study, endurance limit and fatigue behavior of load carrying fillet welded cruciform joints depending on commonly used welding methods such as SMAW, SAW, MIG and FCAW are investigated. In respect of endurance limit SMAW specimen showes highest result, and then MIG, SAW, FCAW in descending order. However, SMAW specimen showes lowest crack growth rate and it followed by MIG, FCAW, SAW. By these results, it is needed to use SMAW or MIG welding methods for welding structures with small welding capacity and SAW or FCAW methods for large welding structures with respect to economic benefits and operation efficiency of welding. It was also shown fatigue crack growth rate was more influenced by the strenght of welding materials than the endurance limit of welding materials.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.7
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• pp.214-220
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• 1999

In order to use effectively a machinery part with fillet, it is necessary to determine a proper fillet shape in design step, Study of such problem by fracture mechanical criterion is rare. So, this paper focuses on the design of fillet radius in fracture mechanical aspect. Finite element method was used to obtain crack tip stress intensity factor. Stress intensity factor was calculated by COD(crack opening displacement0method proposed by Ingraffea and Manu. The parameter used in this study are thickness ration, filet radium and crack length . If fillet radius increase , crack propagation may be accelerated. Critical crack length is inversely proportional to fillet radius.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.393-396
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• 2000

본 연구에서는 필렛엔드밀을 이용하여 복합곡면을 가공하기 위한 새로운 접근방법을 제안한다. 이 방법은 "곡선기반 접근방법"으로 기존의 "점기반 접근방법"에 비하여 몇 가지 특징들을 가지고 있다. 본 연구에서는 다면체로 표현된 곡면을 대상으로 하고 있는데, 볼록한 모서리와 꼭지점에서는 정확히 옵셋시키고 오목한 부위에서는 옵셋 곡면이 겹치는 것을 허용한다. 옵셋된 곡면을 절단 평면으로 자르고, 같은 평면상에 있는 교선 중에서 겹치는 부분의 윗 부분을 택하면 공구 간섭이 제거된 공구 경로를 얻게된다. 즉 계산이 복잡한 오목지역에서의 옵셋 시 발생되는 간섭을 2차원 평면상에서 제거함으로써 계산 과정을 단순화시키고 안정적으로 만든다. 본 연구에서 제안한 방법은 PC에서 VC++로 구현되었으며 몇 가지 적용 예를 보여 주고 있다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.8
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• pp.839-846
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• 2007

Nd:YAG pulse laser fillet welding of stainless steel plate was simulated to find welding condition by using commercial finite element code MARC. Full model of AISI 304 stainless steel plate was considered and user subroutines were applied to boundary condition for the heat transfer. Material properties such as conductivity, specific heat, mass density and latent heat were given as a function of temperature. As results, Three dimensional heat source model for pulse laser beam conditions of fillet welding has been designed by the comparison between the finite element analysis results and experimental data on AISI 304 stainless steel plate. Nd:YAG laser welding for AISI 304 stainless steel was successfully simulated and it should be useful to determine optimal welding condition.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.4
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• pp.65-73
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• 2004

Fatigue crack growth from surface defects is one of the most important subjects for the evaluation and the assurance of safety in pressure vessels, piping systems, LPG/LNG fuel tank and other various structures. This paper attempts to analysis some practical or general problems such as the estimation of crack growth life to penetrate the plate thickness, based on fatigue crack growth a single surface flaw and the interaction of multiple flaws. An experiment on the coalescence of multiple undercuts was carried out under cyclic tension condition as a attempt to the analysis of multiple crack problems. It is noted that the fracture strength is characterized by the analogy to that in a single crack growth.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.479-484
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• 2004

For the rational design of welded joint, it is needed to assess repeatedly the fatigue life of the joint with various dimensions and welding conditions. In this paper, an automation of repeated process of fatigue life assessment for welded cruciform joint was studied. The process is related to stress analysis in vicinity of weld-toe and fatigue life assessment based on analyzed stress distribution. With the change of design condition including dimensions and/or welding heat input, the above two works have to be performed. Using the commercial tool for system integration, ModelCenter, an automation of the repeated process for welded cruciform joint based on 2D modeling was achieved. In this automation system, data exchanges between programs regardless of commercial or in-house one work well, and parametric studies for optimal design can be performed.

• Journal of Welding and Joining
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• v.7 no.4
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• pp.22-29
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• 1989

In this paper weld distortion both in butt and fillet welds by flux cored arc welding has been investigated by changing welding parameters such as heat input and plate thickness, and the weld distortion was expressed as a function of welding parameters adopting the inherent strain theory as proposed by Watanabe and Satoh in 1961. As results of the research it is proposed that transverse shrinkage in root pass butt welds in proportional to ln[(Q/t_-tan.theta.] where Q is heat input(cal/mm), t is plate thickness(mm), and 2.theta. is groove angle(degree), and angular distortion .phi.(radian) in one pass of fillet welds has the following relationship: .phi..var.(Q/ $t^{1.5}$)$^{3}$exp[-(Q/ $t^{1.5}$ )$^{2}$3/] These equations provide us with basic tools to predict the amount of weld distortion in welded structures.

• Proceedings of the KWS Conference
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• 2000.10a
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• pp.110-113
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• 2000

• Proceedings of the KWS Conference
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• 1998.05a
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• pp.96-101
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• 1998

• Proceedings of the KWS Conference
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• 1998.05a
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• pp.69-71
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• 1998