• 대한기계학회논문집A
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• 제24권5호
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• pp.1146-1154
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• 2000

Fatigue strength of NiAl and Ni$_3$Al particulate reinforced aluminum alloy composites fabricated by the diecasting method was examined at room and elevated temperatures. The results were compared wit h that of SiC particulate reinforced one. The particulate reinforced composites showed some improvement in the static and fatigue strength at elevated temperatures when compared with that of Al alloy. The composites reinforced by intermetallic compound particles showed good fatigue strengths at elevated temperatures especially $Ni_3AI_{p}/Al$ alloy composite showed good fatigue limit up to high temperature of 30$0^{\circ}C$. Adopting intermetallic compound particle as a reinforcement phase, it will be possible to develop MMC representing better fatigue property at elevated temperature.

• 한국해양공학회지
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• 제23권5호
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• pp.45-53
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• 2009

In this study, Finite Element Analysis (FEA) was used to decide three kinds of material property of vibration proof rubber with the unique characteristic of non-linear and large deformation. As well, three types of hardness (Hs 50, 55, 60) were compared with the result of fatigue tests, fatigue life was able to be predicted. The request for fatigue life becomes strict more and more as increasing stress under conditions like a compaction, high load and high temperature for parts because it is main characteristics of rubber mount for automotive. Regarding to the fatigue life under dynamic deformation condition, it can be predicted as checking forced deformation extends and its frequency and its strain-life curve. As for material property tests of uniaxial tension test, uniaxial compression test, pure shear test, Ogden model was used for FEA by observing relations between stress and strain's rate as curve fitting. As a result of FEA, fatigue life for rubber mount was predicted and accorded well with the experimental data of fatigue test with hourglass specimens. In addition, its property of the predictable fatigue life method suggested in this study was accorded well with the experimental data by comparing the predicted fatigue life of FEA with the result of fatigue test for rubber component of engine rubber mount.

• 대한기계학회논문집
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• 제18권11호
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• pp.2894-2901
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• 1994

Many researchers presented a probabilistic and statistical property of the material strength. However, the study on probabilistic and statistical property of fatigue fracture toughness has not been nearly presented. Major objectives in this paper are to compare the statistical test results of fatigue fracture toughness with those obtained in the tensile experiments, and to recognize the size effect for the probabilistic and statistical property by using specimens with various thickness.

• Composites Research
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• 제30권6호
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• pp.406-409
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• 2017

The thin-walled cylindrical tubes are frequently used for the evaluation of fatigue property of composites. But the curvature of the tubular specimen induces interlaminar normal stress which may affect the fatigue property. In this paper interlaminar normal stress effect on the fatigue behaviour of thin-walled graphite/epoxy tubes $[{\pm}45]_s$ composites was studied experimentally. It was concluded that the interlaminar normal stress induced by the curvature of the cylinder has no discernible effect on the fatigue life. But excessive internal pressure can produce the stiffness increase and this affects the fatigue life of the cylindrical tubular composite.

• 소성∙가공
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• 제26권6호
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• pp.356-364
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• 2017

In this study, submerged arc cladded Fe-Cr-Ni-Mo-CuWNbV-C stainless steels containing various Cr contents between 11.2 wt.% and 16.7 wt.% were prepared with fixed C content at about 0.14 wt.%. Using these alloys, changes in microstructure, tensile property, and thermal fatigue property were investigated. Phase fraction of delta-ferrite was increased gradually with increasing Cr content. However, tensile strength, hardness, and thermal fatigue resistance appeared to be decreased. When the microstructure of delta-ferrite was observed, it was revealed that the mesh structure retained up to about 15% Cr content. Although thermal fatigue resistance was almost the same for Cr contents between 11.0 and 14.5 wt.%, it was significantly decreased at higher Cr contents. This was evident from mean value of crack lengths of 10 largest ones. Evaluation of thermal fatigue resistance on alloys with various Cr contents revealed the following important results. First, the reproducibility of ranking test was excellent regardless of the number of cycles. Second, thermal fatigue resistance was increased in proportion to true tensile fracture strength values of overlay materials. Finally, the number of thermal fatigue cracks per unit length was increased with increasing true tensile fracture strength.

• 한국의류학회지
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• 제27권11호
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• pp.1291-1299
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• 2003

In order to design the better brassiere in terms of appearance and functions, various parameters of the materials should be considered; in this study, fatigue properties and subjective sensation of wing materials and its relation to the preference for a brassiere was investigated. After the survey of commercially available products, five elastic fabrics such as cotton, Modal, polyester, nylon, and Tactel, all of which contain 10% polyurethane, were chosen as specimens. Fabric growth were determined to evaluate fatigue properties. Qmax was determined to evaluate the warm-cool feeling. For the sensory test, semantic differential scale which contains 15 adjectives were developed. Fatigue properties were very similar at the 20% elongation irrespective of the duration of tension, but at 40% and 100% elongation, man made fabric showed less growth than cellulose fabrics. The factor analysis showed four factors such as sense of warmth, smoothness, weight and elasticity. Preference of the specimens was ranked in the order of Tactel>Modal>cotton>nylon>polyester.

• International Journal of Naval Architecture and Ocean Engineering
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• 제4권2호
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• pp.132-140
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• 2012

This study aims to assess fatigue property by the static overload and average load in the fillet welded joints which is on the ship structural steel having gusset welds. To this end, a small specimen was made, to which the same welding condition for the actual ship structure was applied, to perform fatigue tests. In this study, a method to simply assess changes in welding residual stress according to different static overload was suggested. By measuring actual strain at the weld toe, the weld stress concentration factor and property which is determined by recrystallization in the process of welding were estimated to investigate the relation between overload and fatigue strength.

• 대한기계학회논문집A
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• 제28권12호
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• pp.1856-1863
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• 2004

In the last 50 years, lead-contained solder materials have been the most popular interconnect materials used in the electronics industry. Recently, lead-free solders are about to replace lead-contained solders for preventing environmental pollutions. However, the reliability of lead-free solders is not yet satisfactory. Several researchers reported that lead-contained solders have a good fatigue property. The others published that the lead-free solders have a longer thermal fatigue life. In this paper, the reason for the contradictory results published on the estimation of fatigue life of lead-free solder is investigated. In the present study, fatigue behavior of 63Sn37Pb, and two types of lead-free solder joints were compared using pseudo-power cycling testing method, which provides more realistic load cycling than chamber cycling method does. Pseudo-power cycling test was performed in various temperature ranges to evaluating the shear strain effect. A nonlinear finite element model was used to simulate the thermally induced visco-plastic deformation of solder ball joint in BGA packages. It was found that lead-free solder joints have a good fatigue property in the small temperature range condition. That condition induce small strain amplitude. However in the large temperature range condition, lead-contained solder joints have a longer fatigue life.

• 한국강구조학회 논문집
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• 제22권3호
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• pp.209-218
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• 2010

장기간 동안 활하중의 반복재하로 인한 응력누적에 의해 발생하는 피로현상은 강교량의 내구수명을 지배하는 주요 인자중 하나이다. 본 논문은 차량 주행시 동적효과가 비교적 크게 일어나는 일반적인 중소규모의 플레이트 거더교를 대상으로 피로수명에 영향을 미치는 교통하중의 특성을 검토하였다. 검토결과, 피로수명은 시간교통량과 대형차 혼입율이 증가할수록 짧아지고, 교통하중특성의 영향을 받는다는 것을 알 수 있었다. 이러한 검토결과를 토대로 피로수명에 영향을 주는 교통하중의 특성을 대표할 수 있는 새로운 파라미터를 제시하고, 그 유용성을 확인하였다.

• 한국정밀공학회지
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• 제16권8호
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• pp.149-154
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• 1999

FRMLs(Fiber Reinforced Metal Laminates) is a new type of hybrid materials. FRMLs consists of high strength metal and fiber which are laminated using a structural adhesive bond(epoxy resin). The effect of resin mixture ratios on the fatigue crack propagation behavior and mechanical property of Aramid fiber reinforced aluminum composites was investigated. The epoxy, diglycidylether of bisphenol A(DGEBA) was cured with methylene dianiline(MDA) with or without accelerator(K-54). Eight kinds of resin mixture ratio were tested for the experiment ; five kinds of FRMLs(1))epoxy & curing agent) and three kinds of FRMLs(2)(epoxy & curing agent & accelerator). FRMLs(2) have a more effective characteristics on the fatigue crack propagation behavior and mechanical property than FRMLs(1)