• Composites Research
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• v.12 no.6
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• pp.1-7
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• 1999

The change of the coefficients of thermal expansion(CTE) of Carbon/Epoxy was investigated for the temperature variation and a prediction model for the change of CTE was proposed. Elastic properties and CTEs in the principal material directions were measured in the range of room temperature to cure temperature and characterized as functions of temperature. By applying the characterized properties to the classical lamination theory, a computational method to predict the change of CTEs of a general laminate for temperature variation was proposed. the coefficients of thermal expansion of laminates with various stacking sequences were measured and compared with those predicted. Good agreements between the predicted results and the experimental data show that the c hanges of CTEs of a general laminate for temperature variation can be predicted well by using the proposed method.

• Korean Journal of Crystallography
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• v.13 no.2
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• pp.69-72
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• 2002

The interlaminar problems near the free edge of composite laminates are analyzed in this paper. CFRP specimen (［+40/-40］s) and interleaved specimen (［+40//-40］s) with non-woven carbon tissue (NWCT) are discussed under tensile loading condition. The symbol “//”means that the NWCT is located between the CFRP interfaces. The NWCT has carbon short fibers which are discretely distributed with the in-plane random orientation. It was reported/sup 3)/ that the Mode Ⅱ interlaminar fracture toughness of CFRP laminates with NWCT is increased largely and the Mode I interlaminar fracture toughness is not changed significantly. Mode Ⅲ interlaminar fracture toughness is also an important factor in composite structures. But it is not easy to experimentally investigate the Mode Ⅲ interlaminar fracture toughness. The objective of this work is to study the effect of the NWCT and to fundamentally understand the Mode Ⅲ interlaminar shear characteristics of laminated composites with NWCT in the vicinity of a free edge by using finite element method analysis.

• Journal of Aerospace System Engineering
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• v.12 no.6
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• pp.58-65
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• 2018

The dynamic characteristics of the deployable composite parabolic reflector with several panels were numerically and experimentally investigated. The deployment mechanism is designed to efficiently fit in a small volume. The parameters guiding the deployment are determined by considering; the number of panels, folding/twisting angles, and the driving forces of actuating devices. The panels are fabricated using carbon fiber reinforced plastics (CFRPs). The zero-gravity simulator is manufactured for the unfolding test. The deployment behaviors of the reflector are finally observed.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.41-44
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• 2007

In repairing and reinforcing modem architecture, altering the features must be minimized. We concluded that inserting CFRP(Carbon Fiber Reinforcement Polymer) plate method is the most appropriate reinforcing method that minimize altering the features. This study focuses on the effect of reinforcement by inserting CFRP plate in the timber beam of the modem architecture's roof truss. We concluded that inserting CFRP plate method is highly influenced by its parent material, however, it is obvious that materials had reinforced by this method in general. We guess that this method is applicable to reinforcement in the modern architecture's roof truss in various ways.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.593-600
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• 1998

In this study, confinement stress of concrete compression members rehabilitated with C.F.L were analyzed from the test. Test parameters are spacing, thickness and ply of rehabilitation material. Displacement, failure load were measured during test. The failure mode and ultimate load were analyzed from these measured data. In this study, a model equation for calculation of the confining stress with C.F.L was proposed based on the test results investigated here. The proposed equation included the effects of spacing, thickness and ply of rehabilitation material.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.607-612
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• 1998

In this study, the behavior of R/C beam strengthened with carbon fiber laminate(C.F.L) is analyzed from the test results. Test parameters are the width, the thickness and the length of C.F.L. and method of construction. The failure mode and ultimate load are analyzed from these measured data. Test results shows that the peak moment of specimens strengthened with C.F.L is increased to 1.43~1.90 times of that of non-rehabilitation specimen. The wider lap width, larger amount of rehabilitation materials, the larger strength is obtained.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.8
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• pp.1930-1938
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• 1994

In this paper, the effects of temperature change on the impact of CFRP laminates was experimentally studied. Composite laminates used for this experiment are CFRP orthotropic laminated plates, which have two-interfaces$[0_6^{\circ}/90_7^{\circ}]_s$ and four-interfaces$[0_3^{\circ}/90_6^{\circ}/0_3^{\circ}]_s$. The interrelations between the impact energy vs. delamination area, the impact energy vs. residual bending strength, and the interlayer delamination area vs. the decrease of the residual flexural strength of carbon fiber epoxy composite laminates subjected to FOD(Foreign Object Damage) under high temperatures were experimentally observed.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.258-261
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• 2006

This study investigates the flexural behavior and strengthening performance of RC beams with unbonded prestressing CFRP laminates through static bending tests. The aluminum anchorage system has been developed in tins study and successfully applied to the test specimens. The prestressing level of CFRP laminatehas was 0 %, 20 %, 30% and 50 % of its tensile strength. Experimental results revealed that RC beams with unbonded prestressing CFRP laminates showed increased crack load and yield load according to the level of prestress. It has also been observed that the length of the CFRP laminates does not have significant effect on the maximum load.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.226-229
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• 2006

Strengthening with externally post-tensioned CFRP strips is more effective in increasing load carrying capacity of existing structures as well as reducing crack width and deflection. This study developed concrete embedded anchorages system for externally post-tensioned CFRP strips, and carried out experimental study to verify anchoring performance quantitatively. Through experimental results, anchoring strength of concrete embedded anchorage were quantified into shear strength of anchor bolt, bearing strength of concrete at the front of anchor plate and bond strength between anchor plate and concrete surface. In addition, overall anchoring performances according to combination of each unit force are examined in this study.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.679-684
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• 1997

In this study, compressive strengths of reinforced concrete compression members rehabilitated with C.F.L. were analyzed from the test. Test parameters are spacing, spliced length, and section area of rehabilitation material. Displacement, failure load were measured during test. The failure mode and ultimate load were analyzed from these measured data. Test result shows that closer spacing of C.F.L. is more effective. strengthening with 1-ply C.F.L. is more effective than that of specimen with 2-ply C.F.L. The compressive capacity of specimen spliced ($\pi$.D)/2 shows almost similar strength to that of non-spliced specimen. The ultimate load carrying capacity of specimen strengthened with C.F.L. is increased to 1.11~1.68 times of that of non-rehabilitation specimen.