• KEPCO Journal on Electric Power and Energy
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• 제7권1호
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• pp.125-128
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• 2021

This paper presents the root cause failure analysis of the circulating water pump in the 560 MW thermal power plant. A fractured austenitic stainless-steel shaft operated for 24 years was examined. Fracture morphology was investigated by micro and macro-fractographic analysis. The metallurgical analyses including chemical analysis, metallography and hardness testing were performed. The analysis reveals that the pump shaft was fractured due to the reverse bending load with combination of rotating bending load. Corrective actions for plant operator was recommended based on the analysis.

• 한국태양에너지학회 논문집
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• 제24권4호
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• pp.27-33
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• 2004

Mechanical load measurements on blade and tower of Vestas 100 kW wind turbine has been reformed in Wollyong test site, Jeju island. The experimental procedure for the measurement of wind turbine loads, such as edgewise(lead-lag) bending moment, flapwise bending moment, and tower base bending moment, has been established. The test facilities consisting of strain-gauges, telemetry and T-Mon system are installed in the wind turbine. Strain gauges are on-site calibrated against load cell prior to monitoring the wind turbine loads. Using the test setup, the loads on the components are being measured and analysed for various external conditions of the wind turbine. A set of results for near rated wind speed has been presented in this paper.

• Advances in concrete construction
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• 제8권1호
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• pp.33-37
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• 2019

The present investigation is mainly focused on studying the flexural behavior of reinforced geopolymer concrete (RGPC) beams under pure bending. In this study, copper slag (CS) was used as a partial replacement of fine aggregate. Sand and CS were blended in different proportions (100:0, 80:20, 60:40 and 40:60) (sand:CS) by weight. Fly ash and ground granulated blast furnace slag (GGBS) were used as binders and combination of sodium hydroxide (8M) and sodium silicate solution were used for activating the binders. The reinforcement of RGPC beam was designed as per guidelines given in the IS 456-2000 and tested under pure bending (two-point loading) after 28 days of ambient curing. After conducting two point load test the flexural parameters viz., moment carrying capacity, ultimate load, service load, cracking moment, cracking load, crack pattern and ultimate deflection were studied. From the results, it is concluded that RGPC beams have shown better performance up to 60% of CS replacement.

• Journal of Korean Neurosurgical Society
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• 제46권2호
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• pp.144-151
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• 2009

Objective: To compare two testing protocols for evaluating range of motion (ROM) changes in the preloaded cadaveric spines implanted with a mobile core type Charite$^{TM}$ lumbar artificial disc. Methods: Using five human cadaveric lumbosacral spines (L2-S2), baseline ROMs were measured with a bending moment of 8 Nm for all motion modes (flexion/extension, lateral bending, and axial rotation) in intact spine. The ROM was tracked using a video-based motion-capturing system. After the Charite$^{TM}$ disc was implanted at the L4-L5 level, the measurement was repeated using two different methods: 1) loading up to 8 Nm with the compressive follower preload as in testing the intact spine (Load control protocol), 2) loading in displacement control until the total ROM of L2-S2 matches that when the intact spine was loaded under load control (Hybrid protocol). The comparison between the data of each protocol was performed. Results: The ROMs of the L4-L5 arthroplasty level were increased in all test modalities (p < 0.05 in bending and rotation) under both load and hybrid protocols. At the adjacent segments, the ROMs were increased in all modes except flexion under load control protocol. Under hybrid protocol, the adjacent segments demonstrated decreased ROMs in all modalities except extension at the inferior segment. Statistical significance between load and hybrid protocols was observed during bending and rotation at the operative and adjacent levels (p< 0.05). Conclusion: In hybrid protocol, the Charite$^{TM}$ disc provided a relatively better restoration of ROM, than in the load control protocol, reproducing clinical observations in terms of motion following surgery.

• Steel and Composite Structures
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• 제23권5호
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• pp.597-610
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• 2017

This paper presents a mathematical model for fixed-end moments of I-sections with straight haunches for the general case (symmetrical and/or non-symmetrical) subjected to a concentrated load localized anywhere on beam taking into account the bending deformations and shear, which is the novelty of this research. The properties of the cross section of the beam vary along its axis "x", i.e., the flange width "b", the flange thickness "t", the web thickness "e" are constant and the height "d" varies along of the beam, this variation is linear type. The compatibility equations and equilibrium are used to solve such problems, and the deformations anywhere of beam are found by the virtual work principle through exact integrations using the software "Derive" to obtain some results. The traditional model takes into account only bending deformations, and others authors present tables considering the bending deformations and shear, but are restricted. A comparison between the traditional model and the proposed model is made to observe differences, and an example of structural analysis of a continuous highway bridge under live load is resolved. Besides the effectiveness and accuracy of the developed models, a significant advantage is that fixed-end moments are calculated for any cross section of the beam "I" using the mathematical formulas.

• Structural Engineering and Mechanics
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• 제46권1호
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• pp.39-51
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• 2013

An extremum method is presented to predict the wrinkling characteristics of the inflated cone in bending. The wrinkling factor is firstly defined so as to obtain the wrinkling condition. The initial wrinkling location is then determined by searching the maximum of the wrinkling factor. The critical wrinkling load is finally obtained by determining the ratio of the wrinkling moment versus the initial wrinkling location. The extremum method is proposed based on the assumption of membrane material of beam wall, and it is extended to consider beam wall with thin-shell material in the end. The nondimensional analyses show that the initial wrinkling location is closely related to the taper ratio. When the taper ratio is higher than the critical value, the initial wrinkles will be initiated at a different location. The nondimensional critical wrinkling load nonlinearly increases as the taper ratio increases firstly, and then linearly increases after the critical taper ratio. The critical taper ratio reflects the highest load-carrying efficiency of the inflated cone in bending, and it can be regarded as a measure to optimize the geometry of the inflated cone. The comparative analysis shows fairly good agreement between analytical and numerical results. Over the whole range of the comparison, the mean differences are lower than 3%. This gives confidence to use extremum method for bending-wrinkling analysis of inflated conical cantilever beam.

• 대한기계학회논문집A
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• 제30권5호
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• pp.568-575
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• 2006

The present paper provides plastic limit load solutions of axial and circumferential through-wall cracked pipes based on detailed three-dimensional (3-D) finite element (FE) limit analysis using elastic-perfectly-plastic behavior. As a loading condition, axial tension, global bending moment, internal pressure, combined tension and bending and combined internal pressure and bending are considered for circumferential through-wall cracked pipes, while only internal pressure is considered for axial through-wall cracked pipes. Especially, more emphasis is given for through-wall cracked pipes subject to combined loading. Comparisons with existing solutions show a large discrepancy in short through-wall crack (both axial and circumferential) for internal pressure. In the case of combined loading, the FE limit analyses results show thickness effect on limit load solutions. Furthermore, the plastic limit load solution for circumferential through-wall cracked pipes under bending is applied to derive plastic $\eta\;and\;{\gamma}$-factor of testing circumferential through-wall cracked pipes to estimate fracture toughness. Being based on detailed 3-D FE limit analysis, the present solutions are believed to be meaningful fur structural integrity assessment of through-wall cracked pipes.

• Steel and Composite Structures
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• 제30권5호
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• pp.471-481
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• 2019

Beam-columns are structural members subjected to a combination of axial and bending forces. Lateral-torsional buckling is one of the main failure modes. Beam-columns that are bent about its strong axis may buckle out of the plane by deflecting laterally and twisting as the values of the applied loads reach a limiting state. Lateral-torsional buckling failure occurs suddenly in beam-column elements with a much greater in-plane bending stiffness than torsional or lateral bending stiffness. This study intends to establish a unique convenient closed-form equation that it can be used for calculating critical elastic lateral-torsional buckling load of beam-column in the presence of a known axial load. The presented equation includes first order bending distribution, the position of the loads acting transversely on the beam-column and mono-symmetry property of the section. Effects of axial loads, slenderness and load positions on lateral torsional buckling behavior of beam-columns are investigated. The proposed solutions are compared to finite element simulations where thin-walled shell elements including warping are used. Good agreement between the analytical and the numerical solutions is demonstrated. It is found out that the lateral-torsional buckling load of beam-columns with mono-symmetric sections can be determined by the presented equation and can be safely used in design procedures.

• 한국자동차공학회논문집
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• 제13권5호
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• pp.171-180
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• 2005

Bending performances of aluminum square tube beams reinforced by aluminum plates under three point bending loads have been evaluated using experimental tests combined with theoretical and finite element analyses. A finite element simulation for the three-point bending test was performed. Basic properties of aluminum materials used for initial input data of the finite element simulation were obtained from the true stress-true strain curves of specimens which had been extracted from the Al tube beams. True stresses were determined from applied loads and cross-sectional area records of a tensile specimen with a rectangular cross-section by real-time photographing, and true strains were obtained from in-situ local elongation measurements of the specimen gage portion by the multi-point scanning laser extensometer. Six kinds of aluminum tube beam specimens adhered by aluminum plates were employed fur the bending test. The bending deformation behaviors up to the maximum load described by the numerical simulation were in good agreement with experimental ones. After passing the maximum load, reinforcing plate was debonded from the aluminum tube beam. An aluminum tube beam strengthened by aluminum plate on the upper web showed an excellent bending capability.

• 한국안전학회지
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• 제21권6호
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• pp.14-19
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• 2006

This study performed burst tests using real-scale pipe elbow containing simulated local wall-thinning to evaluate the effects of circumferential thinning angle and bending load on the failure pressure of wall-thinned elbow. The tests were carried out under the loading conditions of internal pressure and combined internal pressure and bending loads. Three circumferential thinning angles, ${\theta}/{\Pi}=0.125,\;0.25,\;0.5$, and different thinning locations, intrados and extrados, were considered. The test results showed that the failure pressure of wall-thinned elbow decreased with increasing circumferential thinning angle for both thinning locations. This tendency is different from that observed in the wall-thinned straight pipe. Also, the failure pressure of intrados wall-thinned elbow was higher than that of extrados wall-thinned elbow with the same thinning depth and equivalent thinning length. In addition, the effect of bending moment on the failure pressure was not obvious.