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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal DOI :
The Korean Society for Composite Materials
Editor in Chief :
Volume & Issues
Volume 13, Issue 6 - Dec 2000
Volume 13, Issue 5 - Oct 2000
Volume 13, Issue 4 - Aug 2000
Volume 13, Issue 3 - Jun 2000
Volume 13, Issue 2 - Apr 2000
Volume 13, Issue 1 - Feb 2000
Selecting the target year
Fabrication and Characteristics of
/AC8A Composites by Pressureless Infiltration Process
Composites Research, volume 13, issue 6, 2000, Pages 1~8
The fabrication Process of
/AC8A composites by pressureless infiltration technique and the effects of additive Mg content and volume fraction of particulate reinforcement on mechanical and wear properties were investigated. It was found that the bending strength decreased with increasing volume fraction of
particles. Whereas hardness increased with volume fraction of
particles. The decrement of strength in case of high volume fraction of
particles was attributed to high porosity level. In terms of additive Mg content,
/AC8A composites containing around 5~7wt% of additive Mg indicated the highest strength, and hardness values increased with additive Mg contents. Wear resistance of AC8A alloy were improved by reinforcement of
particles especially at high sliding velocity. Wear property of
/AC8A composites and AC8A alloy exhibited different aspects.
/AC8A composites indicated more wear loss than AC8A alloy at slow velocity region. However a transition point of wear loss was found at middle velocity region which shows the minimum wear loss and wear loss at high velocity region exhibited almost same value as at slow velocity region, whereas wear loss of AC8A alloy almost linearly increased with sliding velocity. It was found that
/AC8A composites containing
volume fraction of 20% exhibited abrasive wear surface regardless of sliding velocity and
/AC8A composites containing
volume fraction of 40% showed slightly adhesive wear surface at low sliding velocity, and it progressed to severe wear as increasing the sliding velocity.
Vibration and Buckling Characteristics for Composite Rectangular Plates Stiffened with Box Beam Stiffeners
Composites Research, volume 13, issue 6, 2000, Pages 9~22
The Rayleigh-Ritz procedure based on energy method is used to present analytically the natural frequencies and the critical buckling loads for four types of loading conditions: (1) uniaxial, (2) biaxial, (3) positive shear and (4) negative shear, of the rectangular, composite plates unidirectionally stiffened with box beam type stiffeners. In analysis the discrete stiffener theory is adopted to present the effect of stiffeners in the plate structure. The convergence study is presented to demonstrate the accuracy of the results. Contour plots of the vibrated and buckled mode shapes are shown for some examples. The effect of various parameters such as numbers, position, aspect ratio of stiffener and layer angle, aspect ratio of plate are focused.
Thermomechanical Analysis of Functionally Gradient
Composite for Electronic Packaging
Composites Research, volume 13, issue 6, 2000, Pages 23~29
The internal residual stresses within the multilayered structure with sharp interface induced by the difference in thermal expansion coefficient between the materials of adjacent layers often provide the source of failure such as delamination of interfaces etc. Recent development of the multilayered structure with functionally graded interface would be the solution to prevent this kind of failure. However a systematic thermo-mechanical analysis is needed for the customized structural design of multilayered structure. In this study, theoretical model for the thermo-mechanical analysis is developed for multilayered structures of the
functionally graded composite for electronic packaging. The evolution of curvature and internal stresses in response to temperature variations is presented for the different combinations of geometry. The resultant analytical solutions are used for the optimal design of the multilayered structures with functionally graded interface as well as with sharp interface.
Characteristics of Falling Weight Impact Responses due to Stacking Sequences of CF/Epoxy Composite Plates
Composites Research, volume 13, issue 6, 2000, Pages 30~38
In this paper, a system of falling weight impact tester was built up to evaluate the impact energy absorbing characteristics and impact strength of CFRP laminate plates in consideration of stress wave propagation theory. Delamination area of impacted specimens for the different ply orientation was measured with ultrasonic C-scanner to find correlation between impact energy and delamination area. Absorbed energy of quasi-isotropic specimen having four interfaces was higher than that of orthotropic laminates with two interfaces. The more interfaces, the more absorbed energy. Hybrid specimen containing GFRP layer was higher than that of normal specimens.
Manufacture and performance test of the composite cantilever arm for electrical discharge wire cutting machine
Composites Research, volume 13, issue 6, 2000, Pages 39~46
Electrical discharge machining (EDM) cuts metal by discharging electric current across a thin gap between tool and workpiece. Electrical discharge wire cutting, a special form of EDM, uses a continuously moving conductive wire as an electrode, and is widely used for the manufacture of punches, dies and stripper plates. In the wire cutting process, the moving wire is usually supported by cantilever arm and wire guides. As the wire traveling speed has been increased in recent years to improve productivity, the vibration of the cantilever arm occurs, which reduces the positional accuracy of the machine. Therefore, the design and manufacture of the cantilever arm with high dynamic characteristics have become important as the machining speed increases. In this paper, the cantilever arm for guiding the moving wire was designed and manufactured using carbon fiber epoxy composite in order to improve the static and dynamic characteristics. Specimens for the composite cantilever arm were manufactured and tested to investigate the effect of the number of reinforcing plies and length fitted to steel flange on the load capacity. Also, the finite element analysis using layer and contact elements was performed to compare the calculated results with the experimental ones. From the results, the prototype of the composite cantilever arm for the electrical discharge wire cutting machine was manufactured and the static and dynamic characteristics were compared with those of the conventional steel cantilever arm.
Low-Velocity Impact Detection of Composite Plate Using Piezopolymer Sensor Signals without Charge Amplifier
Composites Research, volume 13, issue 6, 2000, Pages 47~54
One promising method for impact detection of composite structures is based on the use of piezopolymer thin fim (PVDf) sensor. In this paper, the relationship between the contact force and the signals of the attached strain gage and PVDF sensor to the composite plate subjected to low-velocity impact were derived. The relation for the open circuit and short circuit voltage of PVDF sensor was derived based on the equivalent circuit model of the piezoelectric sensor. The work was then extended to include experimental investigation into the use of short circuit voltage of PVDF sensor without using charge amplifier to detect low-velocity impact. The natural frequencies and damping ratio of the composite plate obtained from the vibration test were used to modify the analytical model and therefore the differences between measured and simulated signal of the modified analytical model in both forward and backward problem were considerably reduced. The reconstructed contact force and simulated sensor signals agreed well with the measured contact force, strain gage signal, and PVDF sensor singanl.
Mechanical Strength Experiment of Carbon/Carbon Composite for Aircraft Brake Disk
Composites Research, volume 13, issue 6, 2000, Pages 55~62
The strength test was done for the Carbon/Carbon rotor disk which is the critical part of a carbon/carbon brake system in an operating time. The loading fixture was designed for the static strength test of a single carbon/carbon brake disk using finite element analysis. To simulate the real dynamic system in a static condition, the friction surface of the rotor disk was fixed and static load was applied to the rotor slot in the circumferential direction. The described failure mechanism of the brake disk can be described as matrix cracking occurred first at the contact surface of the rotor slot, subsequent delamination from the cracked contact surface, and the final fracture at the notch of the rotor.
A Statistical Study of Effective Properties due to Fiber Tow Misalignment and Thickness Change for Plain Weave Textile Composites
Composites Research, volume 13, issue 6, 2000, Pages 63~72
In this paper, statistical treatments of effective properties for plain weave textile composites were presented. Configurations up to 32 layers with varied stacking phase shifts were considered. Effective properties were calculated by numerical simulation in which uni-axial tensile and shear load were applied at unit cell. Sample analysis was utilized to consider the inherent randomness in the phase shift and the results were treated statistically. It was found that effective properties were dependent on stacking phase shifts for thin plain weave textile composites. The distribution of
were skewed and the range of possible values was relatively large. As the number of layers increased, however, the distribution width became narrower and mean values converged. In contrast,
was not affected by phase shifts and thickness changes.