• Title/Summary/Keyword: 비틀림하중

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Prediction of Biaxial Strength and Fatigue Life using the Concept of Equivalent Strength (등가강도 개념에 의한 탄소섬유 복합재료의 이축강도 및 피로수명 예측)

  • 이창수;황운봉
    • Composites Research
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    • v.12 no.2
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    • pp.53-61
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    • 1999
  • A failure criterion must be considered in each failure mode and loading condition to provide easy determining strength parameters, flexibility and rational simplicity. In this study, new failure criterion was developed by introducing equivalent strength under biaxial loading of tension and torsion. The experimental results showed that the equivalent biaxial strength has a power law relation with respect to a parameter, cos($tan^{-1}R_b$). Failure strength under biaxial loadings could be predicted as a function of tensile strength, torsional strength and biaxial ratio. The scattering of experimental data could be predicted using a Weibull distribution function and the concept of equivalent biaxial strength. Also, in this study, a fatigue theory was developed based on a plane stress model which enabled the S-N curve for combined stress states to be predicted from the S-N data for uniaxial loading. The prediction models can be predicted a biaxial strength and fatigue life of general laminated composite naterials under multi-axial loadings.

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Vibration Reduction of Composite Helicopter Blades using Active Twist Control Concept (능동 비틀림 제어기법을 이용한 복합재료 로터 블레이드의 진동 억제)

  • Pawar, Prashant M.;You, Young-Hyun;Jung, Sung-Nam
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.37 no.2
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    • pp.139-146
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    • 2009
  • In this study, an assessment is made for the helicopter vibration reduction of composite rotor blades using an active twist control concept. The piezoceramic shear actuation mechanism along with elastic couplings of composite blades is used for vibration reduction. The rotor blades are modeled as composite box-beams with actuator layers bonded on the outer surfaces of the thin-walled section. The governing equations of motion for helicopter blades are obtained using Hamilton's principle. A time domain unsteady aerodynamic theory with free wake model is used to obtain the airloads. Various rotor configurations with different elastic couplings with appropriate actuator placement are used to investigate the hub vibration characteristics. Numerical results show that a substantial reduction of $N_b$/rev hub vibration can be achieved using the optimal control algorithm.

Evaluation of Internal Bracing Member Forces due to Distortional Behaviors of Tub Section Steel Box Girders (U형 강박스 거더의 뒤틀림 거동에 의한 내부 수직브레이싱 부재력 평가)

  • Kim, Kyung-Sik
    • Journal of Korean Society of Steel Construction
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    • v.23 no.2
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    • pp.249-259
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    • 2011
  • In this study, the distortional behaviors of tub-section steel girders subjected to torsional loading were analyzed, and predictor equations were developed for estimating the member forces induced in the internal bracing system installed in the steel tub girders. Torsional loadings originated either by eccentric vertical loading or girder curvature were decomposed into the pure torsional force component that does not affect the distortional box deformation, and into the distortional force component that directly induces box distortion. The axial member forces induced in the internal cross frames were formulated as a function of the magnitude of torsional loading through the analytical investigation of the interactions between the distortional force component and internal cross frames. To verify the proposed equations, three-dimensional finite element analysis (3D FEA) was conducted for the straight simple-span girder and the three-span continuous girder samples. Very good agreement was found between the member forces from the FEA and the proposed equations.

A New Model for Accurate Nonlinear Analysis of Prestressed Concrete Members under Torsion (비틀림을 받는 프리스트레스트 콘크리트 부재의 새로운 비선형 해석 모델)

  • 오병환;박창규
    • Magazine of the Korea Concrete Institute
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    • v.6 no.2
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    • pp.159-168
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    • 1994
  • The present study proposes a realistic method to analyze the prestressed concrete members subjected to torsion. For this end, this study devises a method to realistically take into account the tensile stiffness of concrete after cracking. The effects of biaxial compressive and tensile loadings on the compressive and tensile strengths of concrete are also taken into account in the present model. The comparison of the present theory with experimental data indicates that the proposed model dipicts reasonably well the actual behavior of prestressed concrete members subjected to torsion. The present model can predict not only the service load behavior, but also up to the behavior of ultimate load stages.

Evaluation of Structural Safety about the Bending and Torsion of Superstructure of the Fish-bone Girder Pier (경골잔교 상부구조의 휨 및 비틀림에 대한 구조 안전성 검토)

  • Ham, Gyu-Sung;Lim, Nam-Hyoung;Park, Jong-Sup;Yoon, Ki-Yong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.4
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    • pp.2000-2005
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    • 2013
  • In this paper, the design load acting on a main girder(spine girder) of fish-bone girder pier is proposed. In order to check the structural safety, numerical analyses using finite element program ABAQUS are performed. It is found that the main girder is affected by a torsional behavior as well as a bending behavior and the major influence loading is the torsional loading. Also, from the stress evaluation of the chosen cross section of the main girder, chosen fish-bone girder pier is structurally safe.

Fatigue Failure Model for the Adhesively Bonded Tubular Single Lap Joint Under Torsional Fatigue Loadings (비틀림 하중하에서의 튜브형 단면겹치기 접착조인트의 피로파괴모델에 관한 연구)

  • 이수정;이대길
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.8
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    • pp.1869-1875
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    • 1995
  • The adhesively bonded tubular single lap joint shows a nonlinear relationship between the applied torque and the resulting displacement under the static-torsional loading, which is induced from the nonlinear properties of the adhesive. However the torque transmission capability in the case of the dynamic-torsional loading is much less than that in the case of the static-torsional loading, the stress level of the adhesive is usually in the region of the linear stress and strain relation and the stress distributions of the joint can be obtained by the linear analysis. In this paper, a failure model for the adhesively bonded tubular single lap joint under the torsional fatigue loading was developed with respect to the adhesive thickness that was a critical factor in predicting the static torque transional-cyclic loadings was proposed.

회전 핀에 의한 이동 하중에 따른 보의 대변형 수치 해석

  • 정일섭
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.05a
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    • pp.65-65
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    • 2004
  • 스프링은 변위에 상응하는 에너지를 저장하는 기계 요소로서 다양한 분야에 적용되고 있으며, 나선형(helical) 스프링, 와선형(spiral) 스프링, 비틀림 막대, 디스크(disk) 스프링, 판(plate) 스프링, 일정 하중(constant force) 스프링 둥 다양한 종류가 있다. 근래 많이 사용되는 LCD 모니터 가운데 일부는 경사(tilt), 회전(pivot), 방향 전환(swivel) 등 모니터의 각도 변화가 가능하도록 제작되며, 이러한 각도 변화시 사용자가 적절한 반력을 느끼도록 인간 공학적으로 설계되어 있다.(중략)

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The Interactive Effect of Translational Drift and Torsional Deformation on Shear Force and Torsional Moment (전단력 및 비틀림 모멘트에 의한 병진 변형 및 비틀림 변형의 상호 작용 효과)

  • Kim, In-Ho;Abegaz, Ruth A.
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.35 no.5
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    • pp.277-286
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    • 2022
  • The elastic and inelastic responses obtained from the experimental and analytical results of two RC building structures under the service level earthquake (SLE) and maximum considered earthquake (MCE) in Korea were used to weinvestigate the characteristics of the mechanisms resisting shear and torsional behavior in torsionally unbalanced structures. Equations representing the interactive effect of translational drift and torsional deformation on the shear force and torsional moment were proposed. Because there is no correlation in the behavior between elastic and inelastic forces and strains, the incremental shear forces and incremental torsional moments were analyzed in terms of their corresponding incremental drifts and incremental torsional deformations with respect to the yield, unloading, and reloading phases around the maximum edge-frame drift. In the elastic combination of the two dominant modes, the translational drift mainly contributes to the shear force, whereas the torsional deformation contributes significantly to the overall torsional moment. However, this phenomenon is mostly altered in the inelastic response such that the incremental translational drift contributes to both the incremental shear forces and incremental torsional moments. In addition, the given equation is used to account for all phenomena, such as the reduction in torsional eccentricity, degradation of torsional stiffness, and apparent energy generation in an inelastic response.

Strength of Reinforced Concrete Members in Pure Torsion (순수(純粹)비틀림을 받는 철근(鐵筋)콘크리트 부재(部材)의 내력(耐力))

  • Shin, Hyun Mook;Kim, Eun Kyun;Kim, Seon Il
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.8 no.2
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    • pp.125-133
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    • 1988
  • To establish the rational design method, it is very important that predict accurately load-deformation response on reinforced concrete members. Torque-twist curves of reinforced concrete members in pure torsion were proposed recently by Collins and Hsu, etc. But, it is found that torsional strength of reinforced concrete members based on Hsu's theory is underestimated in the over-all load region except the ultimate state. In this paper, an attempt is made to present the higher-precision of torsional strength on arbitrary loading condition. For this purpose, constitutive equations are derived from which an estimate can be made of the torsional behavior of reinforced concrete members under the pure torsion. Tension stiffness of concrete in both the cracked and uncracked state have been considered. A softening effect that reduces the strength of the concrete by the diagonal cracking of concrete have been appropriately deliberated. Particularly, the experiments was done with 14 test beams to investigate the validity of theoretical analysis.

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Long-Term Torsional Analysis of Prestressed Concrete Members with the Effects of Creep and Shrinkage (크리이프 및 건조수축의 영향을 고려한 프리스트레스트콘크리트 부재의 장기 비틀림 해석)

  • Oh, Byung Hwan;Park, Chang Kyu
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.14 no.4
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    • pp.741-749
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    • 1994
  • The purpose of the present study is to propose a realistic method to analyze the prestressed concrete members subjected to long term torsional loading. The present study devises a method to realistically take into account the tensile stiffness of concrete after cracking. The effects of biaxial compressive and tensile loadings on the compressive and tensile strengths of concrete are also taken into account in the present model. The salient feature of the present study lies in the fact that the cracking, creep, and shrinkage behavior of concrete and the relaxation of steel have been realistically considered. The comparison of the present theory with experimental data indicates that the proposed model dipicts reasonably well the actual behavior of prestressed concrete members under long-term torsional loadings.

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