• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.226-227
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• 2005

In this study, it was investigated about endurance and fatigue crack propagation rate of according to welding methods of SMAW and FCAW commonly using for welding structures in present. Endurance limits carried out highly in the order of SMAW, FCAW and fatigue crack propagation rate out lowly in the order of SMAW, FCAW. By these results, it is needed to used SMAW welding methods for welding structures with small welding capacity and FCAW methods for large welding structures after consideration about economic gains and operation efficiency of welding. Fatigue crack propagation rate is more effected by strength of welding materials than endurance limit of welding materials according to welding methods..

• Journal of Welding and Joining
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• 제25권1호
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• pp.14-23
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• 2007

A lot of fatigue tests on a material, JIS SM490A, with yielding strength of about 350 MPa and tensile strength of about 520 MPa were carried out. Various butt-welded specimens such as reinforcement removed, as-welded and weld toe ground, several types of fillet-welded specimens and full-size box type components were used. After having obtained S-N curves for the above- mentioned specimens, fatigue strengths were compared to those of foreign design codes, AWS, BS 7608 and ENV. It was found the fatigue strengths at low cycles are not in a good agreement with the foreign codes, but the fatigue limits are in a good agreement.

• 한국안전학회지
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• 제11권4호
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• pp.42-48
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• 1996

Since the fatigue phenomenon is characterized as a probability feature and test data cannot be easily collected number its small sample data are uncertain. Therefore, statistical evaluation methods should necessarily be introduced into data evaluation. With such a basic concept in mind, this study attempted to apply conventional statistical processing methods to the fatigue data and thereby present a new evaluation method in consideration of the fact that the fatigue test is usually performed within a limited number. That is a package evaluation method was adopted which co-realtes parameters between different levels of capacity in E-N or S-N level. So far fatigue limits have been found by means of stiarcase method. But it was also disclosed that this new method has its own disadvantage because limited frequencies are not duely considered.

• 한국자동차공학회논문집
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• 제10권2호
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• pp.186-192
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• 2002

The fatigue crack propagation characteristics were investigated on dissimilar friction weld of two kind of heat-resisting steels (STR3 and STR35) commonly used in valve materials for vehicles. A small circular artificial defect was machined to induce fatigue crack at bonded line, heat affected zone and base metal of the weld on the surface of the specimens. From the results of the experiment, the fatigue limits of the materials STR3 and STR35 were obtained to be 429.0MPa and 409.4MPa respectably. The STR35 base metal and 1.0mm HAZ specimens showed 190% and 82% higher fatigue life than STR3 base metal. And the fatigue life of 1.0mm HAZ specimen was shown 99% on STR3 and 29% on STR35 higher than that of their base metal. But the fatigue life of weld interface specimen was shown 18% on STR3 and 72% on STR35 lower than that of their base metal because of the weld interface separation.

• 전산구조공학
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• 제10권3호
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• pp.15-21
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• 1997

Modern ocean-going vessels are highly dynamically loaded all-welded structures. Traditionally, this fact has been taken into account in the design of ship structures by keeping the overall stress level within permissible limits and by limiting notch effects in the design of local structures. With an improving knowledge of loads and the rapid development of calculation means more detailed calculation-based methods are increasingly introduced. A brief review on fatigue assessment methods used in the design of ship structures has been given during the 1993 IIW International Conference in Glasgow. The rapid development during recent years underlines the importace of the subject and justifies its extended discussion in this paper.

• 대한기계학회논문집A
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• 제26권6호
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• pp.1209-1216
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• 2002

The requirements of coil spring fer higher fatigue strength have been increased to achieve the weight reduction of a vehicle. As the possible increase in fatigue strength by using the conventional shot peening treatment is found to be limited, it is necessary to modify the shot peening treatment. The warm shot peening is a shot peening treatment carried out within warm temperature range. The aim of this paper is to analyze some experimental results concerned with the effect of warm shot peening and to discuss the mechanism of warm shot peening in detail. By the results of rotating bending fatigue test, the fatigue strength of test specimen increases up to 23.8% in the production condition of warm shot peening at 200$\^{C}$ compared with conventional shot peening. The major reason why the warm shot peening is effective to the improvement of fatigue strength is the increase of a compressive residual stress distribution, which can be caused by more effective deformation under the condition of warm temperature.

• 한국기계가공학회지
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• 제5권4호
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• pp.65-71
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• 2006

The lightness of components required on marine and shipbuilding industry is requiring high strength of components. In particular, fatigue failure phenomena, which happen in metal, bring on danger in human life and property. Therefore, antifatigue failure technology takes an important part on current industries. In this study, it is investigated about endurance and fatigue crack propagation rate of according to welding methods such as SMAW, FCAW and SAW commonly used for welding structures in present. Endurance limits carried out highly in the order of SMAW, FCAW, SAW and fatigue crack propagation rate out lowly in the order of SMAW, FCAW, SAW. By these results, it is needed to use SMAW welding method for welding structures with small welding capacity and FCAW, SAW methods for large welding structures after consideration about economic gains and operation efficiency of welding. Fatigue crack propagation rate is more affected by strength of welding materials than endurance limit of welding materials according to welding methods.

• 국제강구조저널
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• 제18권5호
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• pp.1631-1638
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• 2018

In the periodic repainting of steel bridges, often the steel surface has to be prepared by using power tools to remove surface contaminants, such as deteriorated paint film and rust, and to increase the adhesive strengths of the paint films to be applied newly. Surface preparation by bristle roll-brush grinding, which is a type of power tool, may additionally introduce compressive residual stress and increase the fatigue resistance of welded joints owing to the impact of rotating bristle tips. In this study, fatigue tests were conducted for longitudinally out-of-plane gusset fillet welded joints and transversely butt-welded joints to evaluate the effect of bristle roll-brush grinding prior to repainting on the fatigue resistance of the welded joints. The test results showed that bristle roll-brush grinding introduced compressive residual stress and significantly increased fatigue limits by over 50%.

• 한국철도학회논문집
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• 제5권4호
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• pp.222-230
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• 2002

The rotating bogie frame is used in the bogie for a Light Rail Train under development in Korea. In development of the bogie, the structural strength and fatigue characteristics of the rotating bogie frame have been evaluated under the predefined load cases according to the Korean standards for a urban EMU. No part of the rotating bogie frame was subjected to stress beyond the fatigue endurance limits of the material used when grinding the welding of the lower plate link. It is concluded that the rotating bogie frame is safe in view of its static and fatigure strength.

• KEPCO Journal on Electric Power and Energy
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• 제7권2호
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• pp.241-248
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• 2021

High cycle fatigue life for the cables with two different types of clamps is estimated comparatively through acceleration testing. The high cycle fatigue fracture of overhead lines is caused mainly by the aeolian vibration which is induced by vortex shedding. It is necessary to manage the integrity of cables continuedly considering that the aeolian vibration is unavoidable since it occurs in steady and relatively low wind velocity. Two types of clamps which are largely used for overhead lines of the distribution grids are selected and failure data are obtained by step stress testing with a electrodynamic shaker with them. The inverse power law is assumed to describe the stress-life relationship and the fatigue limit at any specified life is supposed to follow Weibull distribution. The life of the cable is defined as the number of cycles to the time that one of strands is completely broken. Finally, the fatigue limits of the cables with two clamp types are estimated at the reference life of 500 Mcycles and compared each other based on a bending vibration amplitude.