• 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.

• Journal of Welding and Joining
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• v.28 no.6
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• pp.45-50
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• 2010

Most of joining processes for machine and steel structure are performed by butt and fillet welding. The mechanical properties and fatigue strength of their welding zone can be effected largely by the differential of generated heat and changes of grain size according to thickness of material and number of passes in welding process. In this study, it was investigated about characteristics of fatigue failure according to thickness of material and number of passes in cruciform fillet weld zone as the basic study for safe and economic design of welding structures. Fracture modes in cruciform fillet weld zone are classified into toe failure and root failure according to non-penetrated depth. It can be accomplished economic design of welding structures considering fatigue strength when the penetrated depth in fillet weld zone is controled properly.

• Journal of the Korean Society for Precision Engineering
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• v.7 no.4
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• pp.149-161
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• 1990

In this study, an optimal shape design was performed on a fillet model which is subject to surface traction through minimizing the maximum stress of the fillet. A 2-dimensional quadratic isoparametirc element with 8 nodes was used in stress analysis for finite element method, and Hooke-Jeeves direct search algorithm was adopted for optimi- zation. From the resulting optimal shape, it was found that the maxium von Mises stress on the boundary of fillet was reduced by 36%, compared to other paper in which the cross sectional area of fillet was minimized. In conclusion, a real optimal fillet shape could be obtained in the viewpoint of yielding, and more pratical fillet design could be accomplished.

• Journal of Welding and Joining
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• v.14 no.5
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• pp.49-58
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• 1996

In Korea Gas Corporation, as one of the pipeline repairing methods, damaged pipelines are sometimes treated with a temporally employment of split sleeve. On conducting the repair process, circumferential fillet and longitudinal groove welding usually must be included. For the case of groove welding, a considerable amount of R&D have been carried out related to property changes, while few study on the property change in fillet welding has been conducted. In this paper, so as to confirm the specification of fillet welding in terms of safety and reliability, properties changed by fillet welding were investigated for two welding processes. Qualifying tests such as reviewing macrostructure and nick-break tests were performed according to API 1104 and ASME section IX. In addition, tensile properties and hardness were evaluated according to KS B0841 and BS 4515. The fillet weld prepared by the qualified procedure showed melting depth of 0.8∼1.3mm and heat affected zone of 2.8∼3.4mm length. No crack and lack of penetration were observed. And the results of hardness and nick-break tests satisfied code requirements. The area crossed by fillet and groove welding line was found to have minimal tensile strength.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.51-53
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• 2006

The purpose of this study is to establish the predictive equation of angular distortion and longitudinal shrinkage force at the intermittent fillet weldment using FEA and experiment. The angular distortion and shrinkage force of the intermittent fillet weldment linearly increases with an increase in the ratio of weld length(Lw) to weld span(Ls). Based on the results, The predictive equation of distortion at the intermittent fillet weldment was defined as a linear function of Lw/Ls and the predictive equation of the distortion for continuous fillet weldment.

• Journal of Welding and Joining
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• v.16 no.5
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• pp.134-141
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• 1998

In this study, a fillet size for bending fatigue strength of one side fillet welded T-joint, used in box type girder and other welding structure, was investigated by bending fatigue test with or without edge preparation and burn through, with variation of joint shape. As a result, the following conclusions were obtained. (1) In one side fillet welded T-joint, the larger the leg length, the greater the bending fatigue strength. The increase in bending fatigue strength. (2) One side filet welded T-joint with edge preparation showed higher bending fatigue strength than that with twofold-large leg length and without edge preparation. (3) In one side fillet welded T-joint without edge preparation, both manual welding and automatic welding were carried out with same condition. In this case, automatic welding shoed deeper penetration and more increased horizontal leg length than manual welding, so that automatic welding offers grater bending fatigue strength. (4) For one side fillet welded T-joint without edge preparation, the ratio(h/t) of the leg length (h) and the main plate thickness (t) in which toe crack can occur was 1.2 over. (5) In one side fillet welded T-joint with edge preparation, the burn through led to reduced bending fatigue strength. However, this bending fatigue strength was higher than that of one side fillet welded T-joint without edge preparation and with a larger leg length.

• Journal of Korean Foot and Ankle Society
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• v.24 no.4
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• pp.148-155
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• 2020

Purpose: Minor foot amputations are performed for recurrent or infected ulcers or osteomyelitis of the diabetic feet. Patients may require a large amount of bone resection for wound closure. On the other hand, this results in more foot dysfunction and a longer time to heal. The authors describe fillet flap coverage to avoid more massive resection in selected cases. This study shows the results of fillet flap coverage for the closure of diabetic foot minor amputation. Materials and Methods: This was a retrospective case series of patients who underwent forefoot and midfoot amputation and fillet flap for osteomyelitis or nonhealing ulcers between March 2013 to November 2017. In addition, the patient comorbidities, hospital days, complications, and duration to complete healing were evaluated. Results: Fourteen fillet flap procedures were performed on 12 patients. Of those, two had toe necrosis, nine had forefoot necrosis, and three had midfoot necrosis. Eleven forefoot amputations and three midfoot amputations were performed. Among forefoot necrosis after a fillet flap, three patients had revision surgery for partial necrosis of the flap, and two patients had an additional amputation. Two patients had additional amputations among those with midfoot necrosis. By the fillet flap, the amputation size was reduced as much as possible. The mean initial healing days, complete healing days, and hospital stay was 70.6 days, 129.0 days, and 60.0 days, respectively. Conclusion: The fillet flap facilitates restoration of the normal foot contour and allows salvage of the metatarsal or toe.

• Journal of Welding and Joining
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• v.32 no.1
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• pp.79-86
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• 2014

The purpose of this study is to determine the proper fillet weld size for the stiffeners on hull bottom plate of crude oil tanker. To achieve it, the effective notch stress and hot spot stress of the fillet weld with leg length specified in the rule were evaluated by using comprehensive FE analyses. Based on the results, the fatigue damages at each location of weld were calculated. Meanwhile the transitional behavior of initial welding distortion in the hull bottom plate under the design conditions was investigated by using a non-linear FEA. Welding distortion and residual stress introduced during fabrication process were considered as initial imperfections. According to FE analysis results, if the fillet leg length satisfies the design criteria of the classification society, the concern on the root failure at the fillet welds in the bottom hull plate during the design life can be negligible. In addition, considering the transitional behavior of the distortion during the service life, the fillet leg length should be minimized.

• Journal of Ocean Engineering and Technology
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• v.13 no.2 s.32
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• pp.51-57
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• 1999

In this study, one side fillet welded T-joint, used in box type girder and other welding structure, was investigated by stress analysis and bending fatigue test without edge preparation, with variation of joint shape. The purpose of this study is to give the welding condiltion and design standard on manufacturing one side fillet welded T-joint. As a result, the following conclusions were obtained. 1) In one side fillet welded T-joint, the larger the leg length and the penetration depth, the greater the bending fatigue strength because reduction of stress and strain on toe and root. The increase of the longitudinal leg length rather than vertical leg length contributed to the increase in bending fatigue strength. 2) In one side fillet welded T-joint without edge preparation, both general manual welding and general automatic welding were carried out with same condition. In this case, automatic welding showed deeper penetration and more increased longitudinal leg length than manual welding, so that automatic welding offers greater bending fatigue strength. 3) For one side fillet welded T-joint without edge preparation with automatic welding, the ratio(h/t) of the leg length(h) and the main plate thickness(t) in which toe crake can occur was 1.0 over.

• Journal of the Korean Society of Safety
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• v.16 no.3
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• pp.1-6
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• 2001

The study is to investigate the influence on the fatigue crack growth behaviors for the welded configuration in pressure vessel stiffener. In order to perform this goal, the automatic welded specimens were prepared. The material is ASTM A516 grade 60 steel used in pressure vessel mainly. In skip welding of pad-on-plate, continuous fillet welding and PWHT specimen, fatigue crack is generally initiated at the starting and end old toe zone, and ruptured at the starting old toe zone. The fatigue life of pad-on-plate of the continuous fillet welding specimen is larger than that of pad-on-plate skip fillet welding specimen about 85% under low load, about 20% under high load and less than that of two-pad continuous fillet welding specimen about 85%. In da/dN-$\Delta$K curve under low load, skip fillet welding specimen of pad-on-plate showed retardation on the initial crack, and the fatigue crack growth rate at the low region of $\Delta$K greater specimen E($3.8 {\times} 10^{-6}mm/cycle$). And the fatigue life of welding specimen was smaller than that of PWHT specimen.