• Korean Journal of Materials Research
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• v.5 no.8
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• pp.979-987
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• 1995

This study has been investigated the Influence of layer thickness on the mechanical properties of cross laminated carbon fiber/epoxy composites. And also the difference of mechanical properties between cross laminated composites of unidirectional prepreg and fabric prepreg has been investigated. Experimental results are showed that the Interlamina Shear Strength(ILSS) of cross laminated carbon fiber/epoxy composites decreased with increasing thickness of unit ply and the decree of delamination in the laminated composites increased as ILSS decreased. Fracture toughness and impact values were found to increase as delamination occurs to some extent in the laminated composites. It Is also shown thats mechanical properties of cross laminates from unidirectional prepreg were better than those of cross laminates from fabric prepreg.

• Journal of Ocean Engineering and Technology
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• v.11 no.2
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• pp.48-56
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• 1997

This work has been investigated in order to study the influence of the moisture absorption on the mechanical pf the glass fiber/epoxy resein composites and the carbon fiber/epoxy resein composites. The types of glass fiber used in the glass fiber/epoxy resein composites were randomly oriented fiber and plain fabric fiber. And carbon fiber.epoxy resein composites was laminated with fabric prepreg which was formed with carbon fiber and epoxy resein. Both composites were immersed up to 100 days in distilled water at $80^{\circ}C$, and then dried up to 3 days in an oven at 80$80^{\circ}C$. Both composites were measured for the weight gain of water(wt.%) and tensile strength through immersion and dry time. Consequently, it was found that the tensile strength of thw glass fiber/epoxy resein composites and the carbon fiber/epoxy resein composites were reduced proportionally to the moisture absortion rate. Also, the tensile strength of glass fiber composites was decreased more than that of the carbon fiber composites. Additionally, it was found that the tensile strength of all composites which decreased by moisture absorption were partly recovered by drying in an oven at 80$80^{\circ}C$.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.4
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• pp.1013-1022
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• 1995

A hybrid composite (APAL;Aramid Patched ALuminum alloy, CPAL;Carbon Patched ALluminum alloy), consisting of a Al 2024-T3 aluminum alloy plate sandwiched between two aramid/epoxy and carbon/epoxy laminate, was developed. Fatigue crack growth behavior was examined at stress ratios of R=0.2, 0.5. The APAL and CPAL showed superior fatigue crack growth resistance, which may be attributed to the crack bridging effect imposed by the intact fibers in the crack wake.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.778-783
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• 1999

The effect of carbon fiber orientation on the tribological properties of carbon fiber/epoxy composites used as a reflecting material for the electromagnetic wave has been investigated. It was found that the carbon fiber/epoxy composite which slides normal to prepreg lay-up direction had less friction and wear that those slides parallel to prepreg fiber lay-up direction due to the increase of delamination between carbon fiber and epoxy. Composite with unidirectional orientation($0/0^{\circ}$) had higher tribological properties than those with multidirectional orientation($0/45/90/-45^{\circ}$ and $0/90^{\circ}$) when the sliding direction was normal to prepreg lay-up direction. This was caused by the debonding between carbon fiber and epoxy which is proportional to contact area between the sliding surface and carbon fiber. Opposite results have been found when the sliding direction was parallel to prepreg lay-up direction due tot he tensile force applied on carbon fiber. In addition, it was shown that wear factor increased with increasing sliding velocity but the friction coefficient did not depend upon the sliding velocity.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.180-183
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• 2009

Composite bipolar plates offer several advantages of low cost, light weight, and ease of manufacturing compared to traditional graphite plate. However, it is difficult to achieve both high electrical conductivity and high flexural strength. In this study, the hybrid carbons filled epoxy composite bipolar plates were fabricated to test electrical conductivity and flexural properties. Graphite powders were used as the main conducting filler and continuous carbon fiber fabrics were inserted to improve the mechanical properties of the composite. This hybrid composite showed improved in-plane electrical conductivity and flexural property. The moldability of the hybrid composite was also improved comparing to the continuous prepreg composite. This study suggested that the continuous carbon fiber inserted graphite/epoxy composites can be a potential candidate material to overcome the disadvantages of conventional graphite composite or continuous prepreg composite bipolar plates.

• Transactions of Materials Processing
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• v.19 no.2
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• pp.127-131
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• 2010

Carbon-epoxy prepreg has been introduced in the forming of the upper and lower swash plates that control the pitch of rotor blade of unmanned helicopter because of its lightweight. Taguchi experimental method has been used by introducing the variables such as arrangement angle, laminated number and forming temperature, in order to obtain the proper forming method by using prepreg satisfying the required strength of the swash plate. In the evaluation of structural safety for the swash plates, three kinds of models are considered by using FE-analysis. In comparison of the hot forged products with Al6061-T6 and the formed products with prepreg, it was found that ultimate tensile strength of the products with prepreg is three times higher than that of the Al6061-T6, and the weight reduction of 68.5g can be achieved by using prepreg swash plates.

• International Journal of Ocean System Engineering
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• v.3 no.3
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• pp.142-146
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• 2013

In this study, the effect of Carbon/PEEK composites on the tribological properties has been investigated. Also, its validity has been tested in the capacity of alternative materials of the Ti-based materials used for artificial hip joint. Moreover, this work evaluated the mechanical properties according to the fiber ply orientation, along with the fractured surfaces of the carbon/PEEK composites. The composites with a unidirectional orientation had higher tribological properties than those with a multidirectional orientation. This was caused by the debonding between the carbon fiber and the PEEK, which was proportional to the contact area between the sliding surface and the carbon fiber. The friction test results showed that there were no significant differences in relation to the fiber ply orientation. However, the friction properties of the carbon/PEEK composites were higher than those of the carbon/epoxy composites. In addition, the results showed that a composite that slid in a direction normal to the prepreg lay-up direction had a smaller friction coefficient than one that slid in a direction parallel to the prepreg lay-up direction.

• Design & Manufacturing
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• v.10 no.2
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• pp.6-11
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• 2016

Designed patterns of slit are introduced to the uni-directional (UD) prepreg in order to enhance the formability of the carbon/epoxy composites without wrinkling and laddering. Three different types of the slit alignment along the thickness direction are applied to analyse the deformation behavior during the compression moulding process of laminates. Degrees of the slit open and the mechanical strength are evaluated based on the level of the compaction pressure in the course of forming process. Results have shown that the mechanical strength of laminates having slits could attain at least 80% of the conventional ones without slits. However, further studies are required to identify the direct relevance of the slit alignment in laminate to the mechanical properties.

• Textile Coloration and Finishing
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• v.29 no.1
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• pp.37-44
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• 2017

An issue of major concern in the utilization of laminated composites based epoxy resin is associated with the occurrence of delaminations or interlaminar cracks, which may be related to manufacturing defects or are induced in service by low-velocity impacts. A strong interfacial filament/brittle epoxy resin bonding can, however, be combined with the high fracture toughness of weak interfacial bonding, when the filaments are arranged to have alternate sections of shear stress. To improve this drawback of the epoxy resin, UV-thermal dual curable resin were developed. This paper presents UV-thermal dual curable resin which were prepared using epoxy acrylate oligomer, photoinitiators, a thermal-curing agent and thermoset epoxy resin. The UV curing behaviors and characteristics of UV-thermal dual curable epoxy resin were investigated using Photo-DSC, DMA and FTIR-ATR spectroscopy. The mechanical properties of UV-thermal dual curable epoxy resin impregnated CF prepreg by UV curable resin content were measured with Tensile, Flextural, ILSS and Sharpy impact test. The obtained results showed that UV curable resin content improves the epoxy toughness.

• Composites Research
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• v.33 no.6
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• pp.341-345
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• 2020

We propose a measurement method for evaluating constituent contents of carbon fiber/epoxy composites through a thermogravimetric analyzer (TGA). The sample used in the test was taken from a strand specimen made of carbon fiber/epoxy tow prepreg, and the change in weight of the sample over time was measured in real time. Using a field emission scanning electron microscope (FE-SEM), we examine the thermal damage condition of the carbon fiber depending on whether resin was removed or not. We find that it was possible to test even a small amount of sample when using TGA vis-à-vis using a conventional muffle furnace. In addition, TGA enables the temperature and exposure time to be controlled, allowing the constituent contents of composite materials to be efficiently and quantitatively evaluated.