• 한국초전도ㆍ저온공학회논문지
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• 제6권1호
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• pp.22-27
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• 2004

It is important to mechanical properties of dielectric paper and cable to optimum electrical insulation design of HTS cable, because the cable has experience of mechanical stress, such as tensile stress, bending stress. Also, it is operated at cryogenic temperature. From the results, it was observed that the tensile strength of PPLP in liquid nitrogen was high more than that of air, but tensile strain decrease sharply. According as tensile strength increases, the breakdown stress of PPLP in liquid nitrogen is decreased. Because PPLP was deteriorated by microcrack and tensile strain. According as bending radius multiple is decrease, the ac and impulse breakdown stress of mini-model cable is sharply decreased.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.90-95
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• 2004

In this study, we proposed new method to mitigate tensile welding residual stress for preventing PWSCC in CRDM nozzle. Residual stress analysis using finite element method is performed to confirm benefit of the new method. In case of applying existing method, tensile axial residual stress decrease by about 28% and tensile hoop residual stress decrease by about 33%. In case of applying the new method, tensile axial residual stress decrease by about 32% and tensile hoop residual stress decrease by about 43%. Therefore, we conclude the new proposed method is more effective to prevent PWSCC than existing method.

• Computers and Concrete
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• 제11권5호
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• pp.383-397
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• 2013

Two-dimensional tensile stresses are occurring at the back of the anchorage of the tendons of prestressed concrete bridges. A new method named "tensile stress region" for the design of the reinforcement is presented in this paper. The basic idea of this approach is the division of an anchor block into several slices, which are described by the tensile stress region. The orthogonal reinforcing wire mesh can be designed in each slice to resist the tensile stresses. Additionally the sum of the depth of every slice defined by the tensile stress region is used to control the required length of the longitudinal reinforcement bars. An example for the reinforcement design of an anchorage block of an external prestressed concrete bridge is analyzed by means of the new presented method and a finite element model is established to compare the results. Furthermore the influence of the transverse and vertical prestressing on the ordinary reinforcement design is taken into account. The results show that the amount of reinforcement bars at the anchorage block is influenced by the layout of the transverse and the vertical prestressing tendons. Using the "tensile stress region" method, the ordinary reinforcement bars can be designed more precisely compared to the design codes, and arranged according to the stress state in every slice.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.315-320
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• 1998

The experimental set-up and one-dimensional analytical model have been developed to investigate the tensile behavior of reinforced concrete member due to restrained drying shrinkage. The experimental results have been compared with the analytical prediction of the maximum residual stress of steel and concrete due to restrained shrinkage. The tensile residual stress concrete by one-dimensional bilinear model shows 0.19 and 0.63 of tensile strength for 0.83% and 3.29 of steel ratio. The residual tensile stress of concrete increases as the steel ratio increases. The effect of steel fiber has not influenced the residual stress due to restrained shrinkage of concrete.

• E2M - 전기 전자와 첨단 소재
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• 제9권10호
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• pp.1033-1039
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• 1996

Electrical and mechanical properties of polymer sheet at cryogenic temperature have been investigated. Tensile stress(and strain at break) in liquid nitrogen(77K) of 79.7MPa(l.2%) and 117.4MPa(2.05%) are evaluated for films of Polypropylene (PP) and Kapton, respectively. Dielectric loss tangent(tan .delta.) of PP and Kapton films is almost independent of the frequency and tensile stress. Also, field strength of PP film at 77K decreases with increasing the tensile stress.

• 한국안전학회지
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• 제19권4호
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• pp.8-13
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• 2004

The purpose of this paper is to investigate the welding residual stress distribution according to the constraint or non-constraint welding condition with titanium commonly using power station, aircraft, and ship. The measuring method of the residual stress was applied stress release rating method with strain gages and a potable strain meter. The x direction residual stress generally showed the tensile residual stress in case of res03int welding. On the other hand, the x direction residual stress under non-restraint welding were changed tensile stress into compressive stress on 15mm away from welding bead center. Also, the y direction residual stress generally showed the tensile residual stress in case of non-restraint welding and the y direction residual stress under restraint welding were changed tensile stress into compressive stress about 60mm away from welding bead center.

• 한국재료학회지
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• 제14권7호
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• pp.500-504
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• 2004

It is well-known that adjacent Pd-MILC enhanced the rate of Ni-MILC. And the phenomena can be explained by tensile stress propagation between amorphous silicon and Pd silicide which is catalyst of crystallization. In this study, we modified tensile stress by changing geometry of amorphous silicon to prove that there is a direct relation between tensile stress and Ni-MILC rate enhancement. When the tensile stress concentrated, the Ni-MILC rate was enhanced more(14.5 ${\mu}m/hr$) by Pd-MILC while the conventional Pd-MILC enhanced Ni-MILC rate was 11 ${\mu}m/hr$. As the result we can be sure that the tensile stress causes the enhancement of Ni-MILC rate.

• Journal of Welding and Joining
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• 제5권1호
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• pp.42-56
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• 1987

Fatigue Fracture behaviors of the TIG-welded aluminum alloys, such as Al 2024-T4, A1 5050-0 and Al 7075-T7 were investigated when a crack propagated from tensile residual stress region and compressive residual stress region. The experimental values were compared with the values expected by the Forman equation. The experimental results are summarized as the following: (1) In case of fatigue crack propagation from residual stress region, the values predicted by Forman equation were Found to exactly corresponded to the experimental values. (2) When the stress intensityfactors affected by compressive residual stress, Kres, were greater than the stress intensity factors by minimum applied stresses. Kmin, the Forman equation was found to be improper to be applied directly, but the equation appeared to be proper, if the stress ratio was modified to zero. (3) The experimental results confirmed that residual stress was relaxed by repeated tensile loading and the relaxing trend was greater in case of compressive residual stress than that of tensile residual stress.

• 대한의용생체공학회:의공학회지
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• 제19권5호
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• pp.495-502
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• 1998

Y.C. Fung[1]에 의한 연조직의 점탄성에 관한 수학적 모델이론 (Fung's Quasi-linear vlscoelastic theory)을 이용하여 인간의 인두조직의 점탄성(vlscoelatlcity)특성을 측정하기 위하여 반복성하중(cyclic load) ,응력완화 (tensile stress relaxation), incremental load, 그리고 일축성인장 (uniaxial tensile) 시험 등을 실시하였다. 실험적으로 측정한 인두조직의 점탄성특성이 이미 조사된 다른 조직의 점탄성특성과 정량적으로 비교되었다. 인두조직의 점탄성특성의 정량화를 위하여 Y.C.Fung의 수학적 모델이 적용되었는데 응력완화(tensile stress relaxation) 시험 측정결과로부터 도출된 표준화된 응력완화(reduced stress relaxation)함수 G(t)와 일축성인장(uniaxial tensile)시험에서 도출된 탄성반응(elastic response)함수 5(t)를 이용하여 시간에 따른 응력의 궤적을 산출하여 이를 반복성 하중(cyclic load)실험에서 측정된 결과와 비교, 분석하였다. 이러한 인두조직의 점탄성특성에 관한 연구결과는 향후 유한요소를 이용한 인두의 생체역학적 모델의 기본 데이터로 이용될 수 있다.

• 한국세라믹학회지
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• 제32권7호
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• pp.793-798
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• 1995

The relaxation of the intrinsic stresses in the diamond films fabricated by the hot filament CVD was studied, and it was confirmed that the tensile intrinsic stresses in the films could be controlled without any degradation in the quality of the diamond films. The tensile intrinsic stresses in the films decreased from 2.97 to 1.42 GPa when the substrate thickness increased from 1 to 10mm. This result showed that the residual stress was affected by the substrate thickness as well as by the interaction between grains. Applying of ＋50 V between the W filament and the Si substrate during deposition, the tensile intrinsic stress in the film deposited at 0 V was decreased from 2.40 GPa to 0.71 GPa. Such large decrease in the tensile intrinsic stress was due to $\beta$-SiC which acted as a buffer layer for the stress relaxation. However, the application of the large voltage above ＋200V resulted in the change of quality of the diamond film, and nearly had no effect on relaxation in the tensile intrinsic stress.