• Title/Summary/Keyword: Tension estimation

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Modeling and Identification of Web Tension Control System with Dancer Roll (댄서롤이 장착된 웹 장력 제어시스템의 모델링 및 규명)

  • Lee, Sang-Hwa;Lee, Jeh-Won;Lee, Hyuk-Jin
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.11
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    • pp.70-76
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    • 2009
  • Web tension control system recently have been applied to OLED(Organic Light-Emitting Diode), RFID of flexible material, e-Paper and PLED(Polymeric LED) and various web control algorithms have being developed for higher productivity and product quality These system need an accuracy model to design and implement controller. In this paper, the web tension control system with dancer roll is mathematically modeled. Mathematical model consists of 8 subsystems and each subsystems can be described as impedance structure which connected by velocity and tension. Mathematical model is different from the estimated model at high frequency range because of structure dynamics which is ignored on mathematical model. The estimated model is derived using ARMAX model. The controller is designed using the estimated model. The step response of the estimated model are compared with that of physical model for a validation of estimated model. The experimental results show a good match between them.

Experimental study of Hydraulic Cable Connection Systems with Re-tensioning and Wireless Monitoring (재긴장과 무선 모니터링이 가능한 유압식 케이블 접합부시스템의 실험에 대한 연구)

  • Kim, Min-Su;Lee, Ki-Hak;Kim, Seong-Beom;Lee, Sung-Min;Baek, Ki-Youl
    • Journal of Korean Association for Spatial Structures
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    • v.11 no.2
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    • pp.71-79
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    • 2011
  • Due to the self-equilibrium status of the cable system, the loss of the tensioning in the cable system results in other cables carrying larger tension forces than those initially calculated by structural engineers. Also, turn-buckle systems, which have been widely used to pre-tension and/or re-tension the cables, are limited to use for small cables and to provide a rough estimation for tension forces. In this study, the re-tensioning cable connection systems were developed to overcome the problems mentioned above. The main objective of the proposed system is to re-tension large cables and measure the exact amount of tension forces of the cable systems. This connection system is also combined with the wireless signal monitoring module so that engineers are able to measure the tension forces any place where the internet is available. This paper presents the development of the re-tensioning cable connection systems and experiment using the real-scale cable systems to verify the fe-tensioning and signal monitoring systems.

Estimation on Clamping Force of High Strength Bolts Considering Temperature Variable of Both Site conditions and Indoor Environments (실내환경과 건설현장 온도변수를 고려한 고력볼트 체결력 예측)

  • Nah, Hwan-Seon;Lee, Hyeon-Ju
    • Journal of the Korean Society for Advanced Composite Structures
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    • v.6 no.3
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    • pp.32-40
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    • 2015
  • The torque shear high strength bolt is clamped normally at the break of pin-tail specified. However, the clamping forces on slip critical connections do not often meet the required tension, as it considerably fluctuates due to torque coefficient dependent on lubricant affected temperature. In this study, the clamping tests of torque shear bolts were conducted independently at indoor conditions and at construction site conditions. During last six years, temperature of candidated site conditions was recorded from $-11^{\circ}C$ to $34^{\circ}C$. The indoor temperature condition was ranged from $-10^{\circ}C$ to $50^{\circ}C$ at each $10^{\circ}C$ interval. As for site conditions, the clamping force was reached in the range from 159 to 210 kN and the torque value was from 405 to $556 N{\cdot}m$. The range of torque coefficient at indoor conditions was analyzed from 0.126 to 0.158 while tensions were indicated from 179 to 192 kN. The torque coefficient at site conditions was ranged from 0.118 to 0.152. Based on this test, the variable trends of torque coefficient, tension subjected temperature can be taken by statistic regressive analysis. The variable of torque coefficient under the indoor conditions is $0.13%/^{\circ}C$ while it reaches $2.73%/^{\circ}C$ at actual site conditions. When the indoor trends and site conditions is combined, the modified variable of torque coefficient can be expected as $0.2%/^{\circ}C$. and the modified variable of tension can be determined as $0.18%/^{\circ}C$.

Tension Estimation for Hanger Cables on a Suspension Bridge Using Image Signals (영상신호를 이용한 현수교 행어케이블의 장력 추정)

  • Kim, Sung-Wan;Yun, Da-Woon;Park, Si-Hyun;Kong, Min-Joon;Park, Jae-Bong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.24 no.3
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    • pp.112-121
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    • 2020
  • In suspension bridges, hanger cables are the main load-supporting members. The tension of the hanger cables of a suspension bridge is a very important parameter for assessing the integrity and safety of the bridge. In general, indirect methods are used to measure the tension of the hanger cables of a suspension bridge in traffic use. A representative indirect method is the vibration method, which extracts modal frequencies from the cables' responses and then measures the cable tension using the cables' geometric conditions and the modal frequencies. In this study, the image processing technique is applied to facilitate the estimation of the dynamic responses of the cables using the image signal, for which a portable digital camcorder was used due to its convenience and cost-efficiency. Ambient vibration tests were conducted on a suspension bridge in traffic use to verify the validity of the back analysis method, which can estimate the tension of remote hanger cables using the modal frequencies as a parameter. In addition, the tension estimated through back analysis method, which was conducted to minimize the difference between the modal frequencies calculated using finite element analysis of the hanger cables and the measured modal frequencies, was compared with that measured using the vibration method.

Static Tension Analysis Method for Floating Tire Breakwater (부 타이어 소파제의 정적 장력 해석 방법)

  • YOON Gil-Su;CHU Weon-Hyo
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.26 no.1
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    • pp.31-40
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    • 1993
  • This paper deals with static tension analysis method for Floating Tire Breakwater(FTB). FTB can be used for the limited wave height. It is especially focused on Goodyear type FTB easily applied to the breakwater for the fisheries cultivating region. The numerical examples for FTB design procedure was reviewed. It is also studied the static analysis method of offshore catenary spread mooring system. The general calculation procedure for the tension versus excursion curves for the multi-line system using the basic catenary relationship was studied. Calculation results showed good agreement with some existing mooring results. To extend this mooring force calculating method to the floating fisheries caitivating cages, the strength of synthetic fiber was considered. This analysis method can be used to the estimation of the mooring force for the floating structures such as floating breakwaters and floating artificial reefs.

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Crack Propagation at Boundary Face of Composite Compact Tension Specimen

  • Cho, Jae-Ung;Han, Moon-Sik
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.22 no.2
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    • pp.337-341
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    • 2013
  • In this study, fatigue crack propagation in composite material under fatigue is investigated by simulation result. When another material on the specimen exists vertically to the crack line, the phenomena that crack may go straight or propagate along the boundary face according to the elastic modulus ratio of another material to matrix are investigated with compact tension specimen by compliance method. Crack propagation direction is evaluated by compliance method. By arranging this study result systematically about the crack propagation behavior due to the stiffness of inhomogeneous material, high-tech material (automobile, aircraft and steel industry) can be improved. The estimation of safety design and life (construction & nuclear power station, etc.) will be of great value industrially.

Estimation of a tensile force in a cable using dynamic characteristics (진동특성을 이용한 케이블의 인장력 산정)

  • Choi, Sang-Hyun;Nam, Dong-Ho
    • Proceedings of the KSR Conference
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    • 2007.05a
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    • pp.461-467
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    • 2007
  • Exact application of the tensile force is critical to high-tension members in civil engineering structures, and thus actual tensile forces have often been estimated in field. To date, a few methodologies have been presented utilizing static and/or dynamic responses of tension members. Each of these methods has its disadvantages as well as advantages in its procedures, accuracy, and equipment requirements. In this paper, the feasibility of a sensitivity based methodology, based on the relationship between the natural frequencies and the applied tensile force, developed by the authors, is verified using the measured data from a cable-stayed bridge structure. From the results, it is shown that the proposed method can be utilized in estimating the tensile force in tension member of a real structure.

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Estimation of tensile strength and moduli of a tension-compression bi-modular rock

  • Wei, Jiong;Zhou, Jingren;Song, Jae-Joon;Chen, Yulong;Kulatilake, Pinnaduwa H.S.W.
    • Geomechanics and Engineering
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    • v.24 no.4
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    • pp.349-358
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    • 2021
  • The Brazilian test has been widely used to determine the indirect tensile strength of rock, concrete and other brittle materials. The basic assumption for the calculation formula of Brazilian tensile strength is that the elastic moduli of rock are the same both in tension and compression. However, the fact is that the elastic moduli in tension and compression of most rocks are different. Thus, the formula of Brazilian tensile strength under the assumption of isotropy is unreasonable. In the present study, we conducted Brazilian tests on flat disk-shaped rock specimens and attached strain gauges at the center of the disc to measure the strains of rock. A tension-compression bi-modular model is proposed to interpret the data of the Brazilian test. The relations between the principal strains, principal stresses and the ratio of the compressive modulus to tensile modulus at the disc center are established. Thus, the tensile and compressive moduli as well as the correct tensile strength can be estimated simultaneously by the new formulas. It is found that the tensile and compressive moduli obtained using these formulas were in well agreement with the values obtained from the direct tension and compression tests. The formulas deduced from the Brazilian test based on the assumption of isotropy overestimated the tensile strength and tensile modulus and underestimated the compressive modulus. This work provides a new methodology to estimate tensile strength and moduli of rock simultaneously considering tension-compression bi-modularity.

Application of Vibration Method for Estimation of Tension Force of Stay Cables in World-Cup Stadiums (월드컵경기장 지지케이블의 장력추정을 위한 진동법의 적용성 평가)

  • Chang, Kug-Kwan
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.13 no.6 s.58
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    • pp.156-165
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    • 2009
  • This study is to consider the character of cables in six World-Cup stadiums constructed in 2002 and to inspect problems on measurement natural frequencies interpretation and application of existing theory. The results of the experiment were shown that it was possible to determine the tension force of the real cables with an accuracy of 8% by taking the cable bending stiffness. But for the range of cable affected greatly by bending stiffness(${\xi}{\leq}7$), it was appeared the tendency to increase estimated error and was considered to need additional study of this range. Estimated tension error could not be improved so much in comparison to the case using single mode of vibration even through multiple modes of vibration were used.