• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.211-214
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• 1999

The stress distribution around the cutout of composite cylindrical shells with a circular or elliptical reinforced cutout subjected to axial compression or tension is studied by asymptotic method. Analytical solutions used a Donnell type orthotropic shell theory are presented by the defined stress concentration factor and are compared to experimental results. The experiment used the universal testing machine (UTM), strain gage and fixtures designed/manufactured for axial tension test of a cylindrical shell is carried and the composite material used in the experiment is plain weave glass fiber reinforced plastic (GFRP).

• 한국초전도ㆍ저온공학회논문지
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• 제4권1호
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• pp.45-59
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• 2002

Evaluation of the mechanical properties of Bi-2223/Ag HTS tapes was carried out by the tension and bending tests. Most of the Bi-2223/Ag tapes retained critical current up to 10 kgf/mm$_2$ axial tension stress, and 0.2% tension strain at room temperature. Applied tension strain exceeding 0.3% in superconducting tapes at 77 K leaded to rapid degradation of the critical current. It was observed that the more filaments, the better axial tension property at 77 K, self-field The influence of bending strain on critical current degradation was revealed to be less sensitive for Bi-2223/Ag HTS tapes with a more number of filaments and higher silver ratio.

• 비파괴검사학회지
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• 제15권2호
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• pp.371-377
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• 1995

각종 산업 분야에서 사용되는 고장력 볼트는 피결함체의 진동이나 충격 하중 및 반복 하중에 의해서 체결력이 약해지는 현상이 발생하는 문제점이 대두되고 있다. 그러므로, 고장력 볼트의 체결력 관리라는 관점에서, 초음파의 음탄성 효과를 이용하여 화력발전소용 터어빈의 고장력 볼트(12Cr.V.Ta)를 모델링한 시험체 내에 입사된 초음파 빔의 공진 주파수 또는 전파 시간을 측정하기 위하여 고장력 볼트의 데이타 값 및 체결 축력 계산식이 입력된 IBM PC를 연결하고, 인장시험기로 하중을 1 ton 씩 증가시키면서 고장력 볼트의 체결축력 및 겉보기 신장량을 구하였으며, 이를 통하여, 고장력 볼트의 설비 안전 검사 시스템의 구축이 가능하였다.

• 콘크리트학회논문집
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• 제12권1호
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• pp.13-22
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• 2000

This paper describes the results obtained from 11 direct tension tests to explore the influence of concrete strength on tension stiffening behavior in reinforced concrete axial members. Three different concrete compressive strengths, 250, 650, and 900kgf/$\textrm{cm}^2$, were included as a main variable, while the ratio of cover thickness-to-rebar diameter was kept constant to be 2.62 to prevent from splitting cracking. As the results, it was appeared that, as higher concrete strength was used, less tension stiffening effect was resulted, and the residual deformation upon unloading was larger. In addition, the spacing between adjacent transverse cracks became smaller with higher concrete strength. The major cause for those results may be attributed to the fact that nonuniform bond stress concentration at both loaded ends and crack sections becomes severer as higher concrete is used, thereby local bond failure becomes more susceptible. From these findings, it would be said the increase in flexural stiffness resulting from using high-strength concrete will be much smaller than that predicted by the conventional knowledge. Finally, a factor accunting for concrete strength was introduced to take account for the effect of HSC on tension stiffening. This proposed equation predicts well the tension stiffening for the effect of HSC on tension stiffening. This proposed equation predicts well the tension stiffening behavior of these tests.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.828-833
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• 2003

In this paper, a study on fracture characteristics of chemically prestressed mortar with addition of expansive additives was carried out. Uni-axial tension tests with reinforced mortar specimen restrained by embedded reinforcing bar and three point bending tests with notched steel fiber reinforced beams were carried out to verify the characteristics of the cracking behavior, the tension stiffening effect due to bond between rebar and mortar, and fracture characteristic. Tension stiffening curve for the chemically prestressed mortar was obtained from uni-axial tension test. And increased fracture energy due to the chemical prestress was also obtained from bending test and tension softening curve for chemically prestressed mortar was also obtained.

• Structural Engineering and Mechanics
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• 제55권2호
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• pp.281-298
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• 2015

In this study, nonlinear transverse vibrations of tensioned Euler-Bernoulli nanobeams are studied. The nonlinear equations of motion including stretching of the neutral axis and axial tension are derived using nonlocal beam theory. Forcing and damping effects are included in the equations. Equation of motion is made dimensionless via dimensionless parameters. A perturbation technique, the multiple scale methods is employed for solving the nonlinear problem. Approximate solutions are applied for the equations of motion. Natural frequencies of the nanobeams for the linear problem are found from the first equation of the perturbation series. From nonlinear term of the perturbation series appear as corrections to the linear problem. The effects of the various axial tension parameters and different nonlocal parameters as well as effects of different boundary conditions on the vibrations are determined. Nonlinear frequencies are estimated; amplitude-phase modulation figures are presented for simple-simple and clamped-clamped cases.

• Interaction and multiscale mechanics
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• 제2권3호
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• pp.223-233
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• 2009

This paper presents a new nonlocal stress variational principle approach for the transverse free vibration of an Euler-Bernoulli cantilever nanobeam with an initial axial tension at its free end. The effects of a nanoscale at molecular level unavailable in classical mechanics are investigated and discussed. A sixth-order partial differential governing equation for transverse free vibration is derived via variational principle with nonlocal elastic stress field theory. Analytical solutions for natural frequencies and transverse vibration modes are determined by applying a numerical analysis. Examples conclude that nonlocal stress effect tends to significantly increase stiffness and natural frequencies of a nanobeam. The relationship between natural frequency and nanoscale is also presented and its significance on stiffness enhancement with respect to the classical elasticity theory is discussed in detail. The effect of an initial axial tension, which also tends to enhance the nanobeam stiffness, is also concluded. The model and approach show potential extension to studies in carbon nanotube and the new result is useful for future comparison.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.402-406
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• 2000

Strain energy function of the isoprene rubber was accurately determined by the experiments of uniaxial tension, planar tension, biaxial tension and volumetric compression. Deformation behavior of alternatively laminated structure of elastomer and reinforced aluminium layers, was analysed by Finite Element method. As a result, Ogden strain energy function obtained from the experiments describes the hyperelastic characteristics of the rubber very well. The compressibility of the rubber reduces axial stiffness of the structure. The axial stiffness of alternatively laminated structure being larger than shear stiffness. Which enables the structure to be shear-deformed easily.

• 한국소음진동공학회논문집
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• 제21권6호
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• pp.580-586
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• 2011

This paper addresses the effect of transverse shear deformation and rotary inertia on the natural frequency of beams under axial loads. It has been reported in the author's paper using a finite element analysis that the Timoshenko effect in a rotating disk deceases and then increases again with increasing rotation speed. To validate the phenomenon, the simply-supported beams under uniform tension are selected in this study since they have exact solutions in vibration problem. The results show that the axial tension in beams would not make the Timoshenko effect decrease monotonically but could make the effect increase again unlike the results reported in the other studies for beams.

• 한국강구조학회 논문집
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• 제28권6호
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• pp.459-465
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• 2016

본 연구에서는 인장이음에 대한 반복하중의 영향을 파악하기 위하여 단순 인장이음을 대상으로 피로시험을 수행하였다. 인장이음의 볼트체결에 따른 축력과 작용하중에 의한 축력의 변화를 측정하였고 반복하중에 의한 볼트의 축력과 파괴양상, 이음의 피로강도를 조사하였다. 인장이음의 구조 상세 변수는 플랜지 두께와 고장력 볼트의 직경으로서 이들의 조합에 따라 볼트와 연결부의 강성이 달라지도록 하였다. 피로시험결과, 반복하중을 받는 인장이음의 파괴모드는 EC3에서 제시하고 있는 정적 파괴모드별 극한하중을 이용하여 평가될 수 있었다. 인장이음의 피로강도는 지레작용을 고려하지 않은 EC3(36)의 피로강도보다 상당히 안전측의 결과로 나타났다. 그러나, 지레작용에 의한 부가축력은 볼트 축력의 증가를 일으키기 때문에 피로강도에 대한 신중한 평가가 필요하다.