• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.2
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• pp.91-96
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• 2015

GRP pipe (Glass-fiber Reinforced Plastic Pipe) lines making use of FRP (Fiber Reinforced Plastic) are generally thinner, lighter, and stronger than the existing concrete or steel pipe lines, and it is excellent in stiffness/strength per unit weight. In this study, we present the result of field test for buried GRP pipes with large diameter(2,400mm). The vertical and horizontal ring deflections are measured for 387 days. The short-term deflection measured by the field test is compared with the result predicted by the Iowa formula. In addition, the long-term ring deflection is predicted by using the procedure suggested in ASTM D 5365(ANNEX) in the range of 40 to 60 years of service life of the pipe based on the experimental results. From the study, it was found that the long-term vertical and horizontal ring deflection up to 60 years is less than the 5% ring deflection limitation.

• Journal of the Korean Wood Science and Technology
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• v.19 no.2
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• pp.40-55
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• 1991

To investigate the influence of cross section geometries on the behavior of composite beams in the case of small span to depth ratio and deep beams. the static flexural behavior of composite I-beams and Box- beams was evaluated. 12 types of composite I -beams composed of LVL flanges and particleboard or plywood web and 3 types of composite Box-beams composed of LVL flanges and plywood web were tested under one-point loading. The load-deflection curves were almost linear to failure, therefore, the behavior of tested composite beams was elastic. The theoretical flexural rigidity of composite beams was calculated and compared with observed flexural rigidity. The highest value was found in I-W type beams and the lowest value was found in G-P type beams. The difference between theoretical and observed flexural rigidity was small. Theoretical total deflection of tested composite beams was calculated using flexural rigidity and compared with actual deflection. Shear deflection of these beams was evaluated by the approximation method, solid crosss section method and elementary method. The difference between actual deflection and expected deflection was not found in D, E and F type beams. This defference was small in G, H and I type beams or Box-beam.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.1
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• pp.7-14
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• 2004

Machining error is defined the normal distance between designed surface and actual tool path with tool deflection. This is inevitably caused by the tool deflection, tool wear, thermal effect and machine tool errors and so on. Among these factors, tool deflection is usually known as the most significant factor of machining error. Tool deflection problem is analyzed using Instantaneous horizontal cutting forces. The high quality and precision of machining products are required in finishing. In order to achieve these purposes, it is necessary work that decrease the machining error. This paper presents a study on the machining error caused by the tool deflection in ball end milling of 2 dimensional surface. Tool deflection model and simple machining error prediction model are described. This model is checked the validity with machining experiments of 2 dimensional surface. These results may be used to decrease machining error and tool path decision.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.4
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• pp.55-64
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• 2001

In this study, hemisphere and cylindrical shapes were machined for different tool paths and machining conditions with ball endmill cutters. Tool deflection, cutting forces and shape accuracy were measured according to the inclination position of the sculptured surface. As the decreasing of inclination position angle, the tool deflection was increased due to the decreased cutting speed when the cutting edge is approaching toward the center. Tool deflection when upward cutting is obtained less than that of downward cutting and down-milling in upward cutting showed the least tool deflection for the sculptured surface. Roundness values were found in least roundness error when down-milling in upward cutting. It is obtained the very little difference between 90。and 45。 of inclination position angle. The best surface roughness value was obtained in upward up-milling and showed different tendency with tool deflection and cutting force. For down-milling, the cutting resistance of the side wall direction is larger than that of feed direction. Therefore, this phenomenon which is received over cutting resistance can be caused of chatter.

• Geomechanics and Engineering
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• v.16 no.3
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• pp.309-320
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• 2018

In this paper, a numerical study using finite element method with considering soil-structure interaction was conducted to investigate the stress and deformation behavior of a sheet pile wall structure. In numerical model, one of the nonlinear elastic material constitutive models, Duncan-Chang E-v model, is used for describing soil behavior. The hard contact constitutive model is used for simulating the behavior of interface between the sheet pile wall and soil. The construction process of excavation and backfill is simulated by the way of step loading. We also compare the present numerical method with the in-situ test results for verifying the numerical methods. The numerical analysis showed that the soil excavation in the lock chamber has a huge effect on the wall deflection and stress, pile deflection, and anchor force. With the increase of distance between anchored bars, the maximum wall deflection and anchor force increase, while the maximum wall stress decreases. At a low elevation of anchored bar, the maximum wall bending moment decreases, but the maximum wall deflection, pile deflection, and anchor force both increase. The construction procedure with first excavation and then backfill is quite favorable for decreasing pile deflection, wall deflection and stress, and anchor forces.

• Advances in concrete construction
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• v.3 no.2
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• pp.91-102
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• 2015

In this paper, the load-deflection analysis of the Carbon Fiber Reinforced Polymer (CFRP) strengthened Reinforced Concrete (RC) slab using Recurrent Neural Network (RNN) is investigated. Six reinforced concrete slabs having dimension $1800{\times}400{\times}120mm$ with similar steel bar of 2T10 and strengthened using different length and width of CFRP were tested and compared with similar samples without CFRP. The experimental load-deflection results were normalized and then uploaded in MATLAB software. Loading, CFRP length and width were as neurons in input layer and mid-span deflection was as neuron in output layer. The network was generated using feed-forward network and a internal nonlinear condition space model to memorize the input data while training process. From 122 load-deflection data, 111 data utilized for network generation and 11 data for the network testing. The results of model on the testing stage showed that the generated RNN predicted the load-deflection analysis of the slabs in acceptable technique with a correlation of determination of 0.99. The ratio between predicted deflection by RNN and experimental output was in the range of 0.99 to 1.11.

• Smart Structures and Systems
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• v.13 no.6
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• pp.975-991
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• 2014

The objective of this study is to develop a reliable method for locating cracks in a beam using data fusion of fractal dimension features of operating deflection shapes. The Katz's fractal dimension curve of an operating deflection shape is used as a basic feature of damage. Like most available damage features, the Katz's fractal dimension curve has a notable limitation in characterizing damage: it is unresponsive to damage near the nodes of structural deformation responses, e.g., operating deflection shapes. To address this limitation, data fusion of Katz's fractal dimension curves of various operating deflection shapes is used to create a sophisticated fractal damage feature, the 'overall Katz's fractal dimension curve'. This overall Katz's fractal dimension curve has the distinctive capability of overcoming the nodal effect of operating deflection shapes so that it maximizes responsiveness to damage and reliability of damage localization. The method is applied to the detection of damage in numerical and experimental cases of cantilever beams with single/multiple cracks, with high-resolution operating deflection shapes acquired by a scanning laser vibrometer. Results show that the overall Katz's fractal dimension curve can locate single/multiple cracks in beams with significantly improved accuracy and reliability in comparison to the existing method. Data fusion of fractal dimension features of operating deflection shapes provides a viable strategy for identifying damage in beam-type structures, with robustness against node effects.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.04a
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• pp.203-209
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• 1999

In this study, the structural deflection analysis of robot manipulator for removing nuclear fuel rod from nuclear reactor vessel is performed by using general purpose finite element code (ANSYS). The structural deflection analysis results reported in this study is very required for the accurate design of robot system. The structural deflection analysis for the manipulator's structural status at which the gripper grasps and draws up the nuclear fuel rod is done, For this beginning structural status of robot manipulator's removing motion, the reaction forces at each joint have static maximum values as reported in the reference(6), and so these forces may cause the maximum deflection of robot structure. The structural deflection analysis is performed for selected four working cases of the proposed structural model and results on deformation, stress for the manipulator's solid body and the deflection at the end of robot manipulator's gripper are calculated. And further, the same analysis is performed for the slenderer manipulator with cross section reduced by one-fifth of each side length of proposed model. The analysis is performed not only for the nuclear fuel rod with weight load of 300kg but also for nuclear fuel rods with weight loads of 100kg, 200kg, 400kg and 500kg. The static structural deflection analysis results show that the deflection value increases as the load increases and the largest value (corresponding to the weight load of 500kg in case 1) is much smaller than the gap distance between nuclear fuel rods. but the largest value for the slenderer manipulator is almost as large as the gap distance, Hence, conclusively, the proposed manipulator's structural model is acceptably safe for mechanical design of robot system.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.325-328
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• 2008

This study is to investigate experimentally the long-term deflection of concrete beams with glass fiber reinforced polymer (GFRP) reinforcing bars subjected to the sustained flexural load for periods of up to 6 months. A total of four beams were tested. All beams were designed with net span of 2,700 mm and rectangular cross-section of 200 mm width and 300 mm depth. From the test results the time-dependent deflection of concrete beams with GFRP bars was about 40 to 70% of the initial deflection. As well as this paper compares the long-term deflection calculated by 440.1R-06 design guide and that of tested beams. The comparison indicated that the calculated long-term deflection overestimate the observed long-term deflection of concrete beams with FRP rebars.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.1003-1008
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• 1997

In this paper, the prediction of cutting force and tool deflection in the ball-end milling process are studied. Identifying various cutting region using Z-map, cutting force in the ball-end milling process can be predicted. Cutting force deflects the tool and the tool deflection changes the cutting force. Tool deflection is included in the cutting force prediction. Tool deflecition also causes machining error of the machined surface. A series of experiments were performed to verify the simulated cutting force and machining error.