• Journal of the Korean Society of Safety
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• v.25 no.6
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• pp.146-154
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• 2010

In this study the experimental results of fatigue specimen for the Strand Stay Cable Assembly of Extadosed bridges is investigated. The fatigue test and tensile experiment is conducted to 6 kinds of specimens. Test specimen OVM250-31 Strand Cable System manufactured by china OVM B-Machinery Co., Ltd, and OVM250-42 Parallel Strand Stay Cable Assembly manufactured by china OVM B-Machinery Co., Ltd, are passed for fatigue test and rupture tensile test. But Test specimen OVM250-42 Parallel Strand Stay Cable Assembly manufactured by korean A-Machinery Co., Ltd, is not passed for fatigue test conducted according to the "Recommendation for Stay Cable Design. The test result are compared to the fatigue criteria of PHI 2001 for cyclic load, and it is concluded that the current korean design code will be needed for representing the fatigue load in Hot Dip Galvanized Strand Stay Cable. It is verified that the new korean specification and quality criteria of Strand Stay Cable and exact experimental applied process will be needed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.761-768
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• 2000

In order to investigate how the fatigue damage effects on the critical properties of superconductor, a fatigue test at room temperature and an Ic measurement test at 4.2K were carried out in this study, respectively, using a 9 strand Cu-Ni/NbTi/Cu composite cable. Through the fatigue test of a 9 strand Cu-NUNbTi/Cu composite cable, a conventional S-N curve was plotted even though there was a possibility of fretting among strands. It was found that the maximum stress corresponding to the inflection point on the S-N curve obtained was nearly the same value as the yielding strength of cable obtained from the static tensile test. However, the effect of cabling in multi-strands superconducting cable on the fatigue strength was not noticeable. The critical current(Ic) measurement was carried out at 4.2K in a NbTi strand out of the fatigued cable. It showed a degradation of lc at high stress amplitude regions over 380NTa, and the degradation became significant as the applied stress amplitude increased.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.5
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• pp.375-387
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• 2023

The subsea power cables are increasingly important for harvesting renewable energies as we develop offshore wind farms located at a long distance from shore. Particularly, the continuous flexural motion of inter-array dynamic power cable of floating offshore wind turbine causes tremendous fatigue damages on the cable. As the subsea power cable consists of the helical structures with various components unlike a mooring line and a steel pipe riser, the fatigue analysis of the cables should be performed using special procedures that consider stick/slip phenomenon. This phenomenon occurs between inner helically wound components when they are tensioned or compressed by environmental loads and the floater motions. In particular, Vortex-induced vibration (VIV) can be generated by currents and have significant impacts on the fatigue life of the cable. In this study, the procedure for VIV fatigue analysis of the dynamic power cable has been established. Additionally, the respective roles of programs employed and required inputs and outputs are explained in detail. Demonstrations of case studies are provided under severely sheared currents to investigate the influences on amplitude variations of dynamic power cables caused by the excitation of high mode numbers. Finally, sensitivity studies have been performed to compare dynamic cable design parameters, specifically, structural damping ratio, higher order harmonics, and lift coefficients tables. In the future, one of the fundamental assumptions to assess the VIV response will be examined in detail, namely a narrow-banded Gaussian process derived from the VIV amplitudes. Although this approach is consistent with current industry standards, the level of consistency and the potential errors between the Gaussian process and the fatigue damage generated from deterministic time-domain results are to be confirmed to verify VIV fatigue analysis procedure for slender marine structures.

• Smart Structures and Systems
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• v.18 no.6
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• pp.1203-1215
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• 2016

When strain sensing cables are under long-term stress and cyclic loading, creep may occur in the jacket material and each layer of the cable structure may slide relative to other layers, causing fatigue in the cables. This study proposes a device for testing the fatigue characteristics of three types of cables operating under different conditions to establish a decay model for observing the patterns of strain decay. The fatigue characteristics of cables encased in polyurethane (PU), GFRP-reinforced, and wire rope-reinforced jackets were compared. The findings are outlined as follows. The cable strain decayed exponentially, and the decay process involved quick decay, slow decay, and stabilization stages. Moreover, the strain decay increased with the initial strain and tensile frequency. The shorter the unstrained period was, the more similar the initial strain levels of the strain decay curves were to the stabilized strain levels of the first cyclic elongation. As the unstrained period increased, the initial strain levels of the strain decay curves approached those of the first cyclic elongation. The tested sensing cables differed in the amount and rate of strain decay. The wire rope-reinforced cable exhibited the smallest amount and rate of decay, whereas the GFRP-reinforced cable demonstrated the largest.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.4
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• pp.129-137
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• 2003

The cable in the cable-supported structures is long, therefore it can be reasonable to apply the different models, compared with those used for general steel elements. This paper compares the statistical models with existing cable fatigue data, after deriving the cdf(cumulative distibution function) with modifying the log-normal distribution, the existing extremal distributions so as to include length effect. The paper presents the appropriate model for analyzing and assessing the fatigue behavior of cable which is being used for actual structures.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 1999.02a
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• pp.30-33
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• 1999

In this study, the fatigue test at room temperature and residual resistivity measurement test at 12K were carried out, respectively, using a 9 strand Cu-Ni/NbTi/Cu composite cable, in order to investigate how the fatigue damage effects on critical properties. Through the fatigue test of a 9 strand Cu-Ni/NbTi/Cu composite cable, a conventional S-N curve was obtained even though there existed a possibility of fretting among strands. From the resistivity measurement of a NbTi strand after fatigue tests, it was found that with increase of the repeated number the RRR increased slightly, and the trend became significant with increase in maximum value of the applied stress amplitude.

• Progress in Superconductivity and Cryogenics
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• v.3 no.1
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• pp.1-5
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• 2001

In order to investigate the effect of fatigue damage on the properties of RRR in this study. fatigue tests at room temperature and residual resistivity measurement tests at 12K were carried out using annealed 9 strand Cu-Ni/NbTi/Cu composite cables Through fatigue tests of NbTi composite cables. a conventional S-N curve could be obtained even though there existed a possibility of fretting among strands, From the resistivity measurement of a NbTi strand after fatigue test, it was found that the RRR of xii·gin strand for annealed cables was 3 times more than that for as-received one. With increasing of fatigue cycles at a sress amplitude level. the RRR decreased. which was resulted from the accumulation of damage such as lattice defects and dislocation within the Cu stabilizer.

• Bulletin of the Society of Naval Architects of Korea
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• v.27 no.1
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• pp.11-16
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• 1990

The effects on the dynamic behaviour of the geometric nonlinearity and large dynamic tensile forces occurring in hostile sea environments must be investigated for assessing extreme tensions and fatigue life expectancy of cable. In this paper, the combined effects on the cable dynamic responses are shown through comparisons between numerical solutions to the cable dynamic equations with geometric nonlinearity and large tensile force terms as well as nonlinear drag term and those to the cable equations with only nonlinear drag term. It is found that, in steady state, the cambined effects increase the maximum dynamic tension and reduce the magnitude of the minimum of the dynamic tension at the middle of the cable. This decrease together with the increase of the maximum dynamic tension, cause the average tension to become higher and, therefore, it may deteriorate the cable fatigue life.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2000.02a
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• pp.104-108
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• 2000

In this study, the fatigue test at room temperature and residual resistivity measurement test at 12K were carried out, respectively, using a 0 strand Cu-Ni/NbTi/Cu composite cable, in order to investigate how the annealing treatment effects on critical properties due to fatigue damage. Through a fatigue test of a 0 strand Cu-Ni/NbTi/Cu composite cables, a conventional S-N curve was obtained even though there existed a possibility of fretting among strands. From the resistivity measurement of a NbTi strand after fatigue tests, it was found that the RRR for annealed cables was 3 times more than that for as-received one, but with increase of the repeated number the RRR decreased which was resulted from the accumulation of damage such as lattice defects dislocation within the Cu stabilizer.

• Wind and Structures
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• v.28 no.4
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• pp.225-238
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• 2019

In this paper a novel and efficient computational framework to estimate the stress range versus number of cycles curves experienced by a cable due to external excitations (e.g., seismic excitations, traffic and wind-induced vibrations, among others) is proposed. This study is limited to the wind-cable interaction governed by the Vortex Shedding mechanism which mainly rules cables vibrations at low amplitudes that may lead to their failure due to bending fatigue damage. The algorithm relies on a stochastic approach to account for the uncertainties in the cable properties, initial conditions, damping, and wind excitation which are the variables that govern the wind-induced vibration phenomena in cables. These uncertainties are propagated adopting Monte Carlo simulations and the concept of importance sampling, which is used to reduce significantly the computational costs when new scenarios with different probabilistic models for the uncertainties are evaluated. A high fidelity cable model is also proposed, capturing the effect of its internal wires distribution and helix angles on the cables stress. Simulation results on a 15 mm diameter high-strength steel strand reveal that not accounting for the initial conditions uncertainties or using a coarse wind speed discretization lead to an underestimation of the stress range experienced by the cable. In addition, parametric studies illustrate the computational efficiency of the algorithm at estimating new scenarios with new probabilistic models, running 3000 times faster than the base case.