• Title/Summary/Keyword: tendon model

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Optimal Static Output Feedback Control of Tendon Driven Master-Slave Manipulator (텐던 구동 마스터-슬레이브 조작기 최적 정적 출력 되먹임 제어)

  • Kang, Min-Sig;Lee, Jong-Kwang;Yoon, Ji-Sup;Park, Byung-Suk;Kim, Ki-Ho
    • Journal of Institute of Control, Robotics and Systems
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    • v.15 no.10
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    • pp.1039-1046
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    • 2009
  • In this work, a bilateral control for a master-slave manipulator system which will be used for handling objects contaminated by radioactivity has been addressed. The links of manipulators are driven independently by individual motors installed on the base and the driving torque is transmitted through pre-tensioned tendons. The measurable variables are the positions and rates of master/slave motors. In the consideration of the flexibility of the tendon and available measurements for control, we proposed an optimal static output feedback control for possible bilateral control architecture. By using modal analysis, the system model is reduced to guarantee the detectability which is a necessity for the static output feedback control design. Based on the reduced model, the control gains are determined to attenuate vibration in the sense of optimality. The feasibility of the proposed control design was verified along with some simulation results.

Numerical Study on the Joints between Precast Post-Tensioned Segments

  • Kim, Tae-Hoon;Kim, Young-Jin;Jin, Byeong-Moo;Shin, Hyun-Mock
    • International Journal of Concrete Structures and Materials
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    • v.19 no.1E
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    • pp.3-9
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    • 2007
  • This paper presents a numerical procedure for analyzing the joints between precast post-tensioned segments. A computer program for the analysis of reinforced concrete structures was run for this problem. Models of material nonlinearity considered in this study include tensile, compressive and shear models for cracked concrete and a model for reinforcing steel with smeared crack. An unbonded tendon element based on the finite element method, that can describe the interaction between the tendon and concrete of prestressed concrete member, was experimentally investigated. A joint element is newly developed to predict the inelastic behavior of the joints between segmental members. The proposed numerical method for the joints between precast post-tensioned segments was verified by comparison of its results with reliable experimental results.

Balanced Ratio of Concrete Beams Internally Prestressed with Unbonded CFRP Tendons

  • Lee, C.;Shin, S.;Lee, H.
    • International Journal of Concrete Structures and Materials
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    • v.11 no.1
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    • pp.1-16
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    • 2017
  • The compression or tension-controlled failure mode of concrete beams prestressed with unbonded FRP tendons is governed by the relative amount of prestressing tendon to the balanced one. Explicit assessment to determine the balanced reinforcement ratio of a beam with unbonded tendons (${\rho}^U_{pfb}$) is difficult because it requires a priori knowledge of the deformed beam geometry in order to evaluate the unbonded tendon strain. In this study, a theoretical evaluation of ${\rho}^U_{pfb}$ is presented based on a concept of three equivalent rectangular curvature blocks for simply supported concrete beams internally prestressed with unbonded carbon-fiber-reinforced polymer (CFRP) tendons. The equivalent curvature blocks were iteratively refined to closely simulate beam rotations at the supports, mid-span beam deflection, and member-dependent strain of the unbonded tendon at the ultimate state. The model was verified by comparing its predictions with the test results. Parametric studies were performed to examine the effects of various parameters on ${\rho}^U_{pfb}$.

Influence of prestressing on the behavior of uncracked concrete beams with a parabolic bonded tendon

  • Bonopera, Marco;Chang, Kuo-Chun;Lin, Tzu-Kang;Tullini, Nerio
    • Structural Engineering and Mechanics
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    • v.77 no.1
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    • pp.1-17
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    • 2021
  • The influence of prestress force on the fundamental frequency and static deflection shape of uncracked Prestressed Concrete (PC) beams with a parabolic bonded tendon was examined in this paper. Due to the conflicts among existing theories, the analytical solutions for properly considering the dynamic and static behavior of these members is not straightforward. A series of experiments were conducted for a total period of approximately 2.5 months on a PC beam made with high strength concrete, subsequently and closely to the 28 days of age of concrete. Specifically, the simply supported PC member was short term subjected to free transverse vibration and three-point bending tests during its early-age. Subsequently, the experimental data were compared with a model that describes the dynamic behavior of PC girders as a combination of two substructures interconnected, i.e., a compressed Euler-Bernoulli beam and a tensioned parabolic cable. It was established that the fundamental frequency of uncracked PC beams with a parabolic bonded tendon is sensitive to the variation of the initial elastic modulus of concrete in the early-age curing. Furthermore, the small variation in experimental frequency with time makes doubtful its use in inverse problem identifications. Conversely, the relationship between prestress force and static deflection shape is well described by the magnification factor formula of the "compression-softening" theory by assuming the variation of the chord elastic modulus of concrete with time.

Three-Dimensional Finite Element Analysis of Tieback Walls in Sand

  • Lim, Yu-Jin;Briaud, Jean-Louis
    • Geotechnical Engineering
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    • v.13 no.3
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    • pp.33-52
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    • 1997
  • A three dimensional nonlinear finite element analysis is used to study the influence of various design decisions for tieback walls. The numerical model simulates the soldier piles and the tendon bonded length of the anchors with beam elements, the unbonded tendon with a spring element, the wood lagging with the shell elements, and the soil with solid 3D nonlinear elements. The soil model used is a modified hyperbolic model with unloading hysteresis. The complete sequence of construction is simulated including the excavation, and the placement and stressing of the anchors. The numerical model is calibrated against a full scale instrumented tieback wall at the National Geotechnical Experimentation Site (NGES) on the Riverside Campus of Texas A&M University. Then a parametric study is conducted. The results give information on the influence of the following factors on the wall behavior : location of the first anchor, length of the tendon unbonded zone, magnitude of the anchor forces, embedment of the soldier piles, stiffness of the wood lagging, and of the piles. The implications in design are discussed.

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Barbed sutures versus conventional tenorrhaphy in flexor tendon repair: An ex vivo biomechanical analysis

  • Colak, Ozlem;Kankaya, Yuksel;Sungur, Nezih;Ozer, Kadri;Gursoy, Koray;Serbetci, Kemal;Kocer, Ugur
    • Archives of Plastic Surgery
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    • v.46 no.3
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    • pp.228-234
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    • 2019
  • Background The management of flexor tendon injuries has evolved in recent years through industrial improvements in suture materials, refinements of repair methods, and early rehabilitation protocols. However, there is no consensus on the ideal suture material and technique. This study was conducted to compare the tensile strength, repair time, and characteristics of 4-strand cruciate, modified Kessler, and 4-strand horizontal intrafiber barbed sutures for flexor tenorrhaphy with a 12-mm suture purchase length in an animal model. Methods The right third deep flexors of 60 adult Leghorn chicken feet were isolated and repaired with a 12-mm suture purchase length. The tendons were randomly assigned to three groups of equal number (n=20 each). Groups 1 and 2 received 4-strand cruciate and modified Kessler repair with conventional suture materials, respectively. A 4-strand horizontal intrafiber barbed suture technique was used in group 3. The repaired tendons were biomechanically tested for tensile strength, 2-mm gap resistance, and mode of failure. Repair times were also recorded. Results The maximum tensile strength until failure was $44.6{\pm}4.3N$ in group 1, $35.7{\pm}5.2N$ in group 2, and $56.7{\pm}17.3N$ in group 3. The barbed sutures were superior to the other sutures in terms of the load needed for 2-mm gap formation (P<0.05). Furthermore, the barbed sutures showed the shortest repair time (P<0.05). Conclusions This study found that 4-strand horizontal intrafiber barbed suture repair with a 12-mm purchase length in a chicken flexor tendon injury model showed promising biomechanical properties and took less time to perform than other options.

Microbiological Safety and Tensile Strength of Gamma Irradiated Porcine Tendon for the Development of Xenografts (이종이식재 개발을 위한 감마선 조사 돼지 인대의 미생물학적 안전성 및 인장강도)

  • Kim, Jeongsoo;Sung, Nak-Yun;Jo, Eu-Ri;Choi, Jong-il;Song, Beom-Seok;Kim, Jaekyung;Lim, Youn-Mook;Lee, Ju-Woon;Lee, Kwang-Won;Kim, Tae-Woon;Byun, Myung-Woo;Kim, Jae-Hun
    • Journal of Radiation Industry
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    • v.5 no.1
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    • pp.75-80
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    • 2011
  • This study was to determine the microbiological safety and tensile strength of gammairradiated porcine tendon for the development of safe xenografts. Escherichia coli and Bacillus subtilis were used as model pathogens and inoculated as $10^6{\sim}10^7log$ colonies forming unit $(CFU)g^{-1}$. As model virus from porcine, porcine parvovirus (PPV), bovine viral diarrhoea virus (BVDV) and poliovirus were inoculated as $10^5{\sim}10^6$ tissue culture infectious dose $(TCID)_{50}g^{-1}$ into porcine skin. The $D_{10}$ value of E. coli and B. subtilis was measured as $0.32{\pm}0.082kGy$ and $4.0{\pm}0.312kGy$, respectively. Additionally, the $D_{10}$ values of PPV, BVDV and poliovirus were also shown as $1.75{\pm}0.131kGy$, $3.70{\pm}0.212kGy$ and $6.26{\pm}0.332kGy$, respectively. Gamma irradiation decreased the tensile strength of porcine tendon. Results indicate that microbiological safety of porcine tendon can be improved significantly by gamma irradiation. However, further studies are needed to improve the tensile strength of gamma-irradiated porcine tendon.

Axisymmetric Modeling of Dome Tendons in Nuclear Containment Building I. Theoretical Derivations (원전 격납건물 돔 텐던의 축대칭 모델링 기법 I. 이론식의 유도)

  • Jeon Se-Jin;Chung Chul-Hun
    • Journal of the Korea Concrete Institute
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    • v.17 no.4 s.88
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    • pp.521-526
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    • 2005
  • Prestressing tendons in a nuclear containment building dome are non-axisymmetrically arranged in most cases. However, simple axisymmetric modeling of the containment has been often employed in practice to estimate structural behavior for the axisymmetric loadings such as an internal pressure. In this case, the axisymmetric approximation is required for the actual tendon arrangements in the dome. Some procedures are proposed that can implement the actual 3-dimensional tendon stiffness and prestressing effect into the axisymmetric model. Prestressing tendons, which are arranged in 3 or 2-ways depending on a containment type, are converted into an equivalent layer to consider the stiffness contribution in meridional and hoop directions. In order to reflect the prestressing effect, equivalent load method and initial stress method are devised and the corresponding loads or stresses are derived in terms of the axisymmetric model. In a companion paper, the proposed schemes are applied into CANDU and KSNP(Korean Standard Nuclear Power Plant) type containments and are verified through some numerical examples comparing the analysis results with those of the actual 3-dimensional model.

Tensile Force Estimation of Externally Prestressed Tendon Using SI technique Based on Differential Evolutionary Algorithm (차분 진화 알고리즘 기반의 SI기법을 이용한 외부 긴장된 텐던의 장력추정)

  • Noh, Myung-Hyun;Jang, Han-Taek;Lee, Sang-Youl;Park, Taehyo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.29 no.1A
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    • pp.9-18
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    • 2009
  • This paper introduces the application of DE (Differential Evolutionary) method for the estimation of tensile force of the externally prestressed tendon. The proposed technique, a SI (System Identification) method using the DE algorithm, can make global solution search possible as opposed to classical gradient-based optimization techniques. The numerical tests show that the proposed technique employing DE algorithm is a useful method which can detect the effective nominal diameters as well as estimate the exact tensile forces of the externally prestressed tendon with an estimation error less than 1% although there is no a priori information about the identification variables. In addition, the validity of the proposed technique is experimentally proved using a scale-down model test considering the serviceability state condition without and with the loss of the prestressed force. The test results prove that the technique is a feasible and effective method that can not only estimate the exact tensile forces and detect the effective nominal diameters but also inspect the damping properties of test model irrespective of the loss of the prestressed force. The 2% error of the estimated effective nominal diameter is due to the difference between the real tendon diameter with a wired section and the FE model diameter with a full-section. Finally, The accuracy and superiority of the proposed technique using the DE algorithm are verified through the comparative study with the existing theories.

Reliability-Based Performance Assessment and Prediction of Tendon Corrosion in K-UHPC Bridges (K-UHPC 교량의 긴장재 부식에 관한 신뢰성 기반 성능 평가 및 예측)

  • Kwon, Kihyon;Park, Sung Yong;Cho, Keunhee;Kim, Sung Tae;Park, Jong Beom;Kim, Byung Suk
    • Journal of the Korean Society of Safety
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    • v.31 no.3
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    • pp.75-81
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    • 2016
  • Tendon corrosion reliability in KICT-ultra high performance concrete (K-UHPC) bridges is assessed and predicted considering uncertainties in flexural bending capacity and corrosion occurrence. In post-tensioning bridge systems, corrosion is a one of most critical failure mechanisms due to strength reduction by it. During the entire service life, those bridges may experience lifetime corrosion deterioration initiated and propagated in tendons which are embedded not only in normal concrete but also in K-UHPC. For this reason, the time-variant corrosion performance has to be assessed. In the absence of in-depth researches associated with K-UHPC tendon corrosion, a reliability-based prediction model is developed to evaluate lifetime corrosion performance of tendon in K-UHPC bridges. In 2015, KICT built a K-UHPC pilot bridge at 168/5~168/6 milestone on Yangon-Mandalay Expressway in Myanmar, by using locally produced tendons which post-tensioned in longitudinal and lateral ways of K-UHPC girders. For an illustrative purpose, this K-UHPC bridge is used to identify the time-variant corrosion performance.