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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal DOI :
The Korean Society for Composite Materials
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Volume & Issues
Volume 16, Issue 6 - Dec 2003
Volume 16, Issue 5 - Oct 2003
Volume 16, Issue 4 - Aug 2003
Volume 16, Issue 3 - Jun 2003
Volume 16, Issue 2 - Apr 2003
Volume 16, Issue 1 - Feb 2003
Selecting the target year
Behavior for 2 Ply Rubber/Cord Laminates
Composites Research, volume 16, issue 4, 2003, Pages 1~9
2 ply laminated composite is regarded to simulate the interply behavior of the belt layer of the tire. It was cone with 3 dimensional FE(Finite Element) analysis to determine interply shear stress and strain. Widthwise, the shear strain was measured by the pin method. These results are compared with those of CLT(classical lamination theory) in center region and those of Kassapoglou's and Kelsey's theory in edge region. In the FE analysis. rubber is assumed as linear elastic material. and rubber/cord laminate as the orthotropic material composed of cord and rubber In the FE result, interlaminar shear stress causing the interlaminar delamination has the largest value in the edge region of the inner rubber layer. Numerical results obtained coincides with CLT well in the center region, and agrees with other theoretical result little in the edge region.
A New Method to Determine the Characteristic Lengths for the Failure Analysis of Composite Joint
Composites Research, volume 16, issue 4, 2003, Pages 10~21
Proposed is a new method to determine the characteristic lengths for the failure analysis of composite joint without experiments. New method uses the result that the stress distribution in the characteristic length specimens is linearly proportional to the applied load. The compressive characteristic lengths calculated by the present method are exactly same as the lengths obtained by the conventional method based on experiment. The new tensile characteristic length is defined using the strength of the notched laminate, while previous methods use the strength of the sound laminate. That change allows calculating the tensile characteristic length numerically without experiment like the compressive characteristic length. Finite element analyses are conducted by MSC/NASTRAN. The interface between the fastener and laminate is modeled by the contact surface element. The finite element results based on the new characteristic lengths show the excellent agreement with experimental results for the Graphite/Epoxy composite .joints.
The Studies on the Fabrication and Properties of Friction Materials toy Aluminium Alloy Disk
Composites Research, volume 16, issue 4, 2003, Pages 22~28
This article deals with the manufacture and test results of asbestos-free friction material for Aluminium at toy disk. In order to obtain optimum formulation, various formulations of fibres, matrix, modifiers, fillers, etc were designed and evaluated. The constant friction and brake dynamometer tests were performed to know weak and strong point for each friction material. The C21 formulation of various tested formulations exhibited superior friction constant(0.38∼38), fade rate (18%) by JASO C406 test mode and maximum wear 1.6 mm. disc wear 0.08 mm by JASO C427 test mode. The surface morphology of AL alloy disk(before and after test) was observed by Scanning Electron Microscope(SEM) and Image Analyzer.
Microscopic Investigation on the Micro-Deformation of Draped Helmet Structure Made of fabric Composite
Composites Research, volume 16, issue 4, 2003, Pages 29~35
In this paper. various tow parameters such as equivalent tow thickness, amplitude of longitudinal tow and tow intervals were investigated and compared with each other by using microscopic observation to find out the exact deformation patterns between both directions of the fabric structure(Longitudinal and Transverse Directions). And those observation results were compared with bias extension. biaxial tests results with dry fabric which has the same tow structure as the draped helmet materials and also compared with prepreg specimen which is cured by autoclave moulding without vacuum and pressure condition. Specimens for the observation were taken from draped helmet which is made of fabric composite(Five Harness Satin Weave). From the observation results, it was found that there are different deformation pattern between tow directions and effect of geometric condition on the deformation of the fabric materials during draping process was verified.
Optimum Design of Composite Structures using Metamodels
Composites Research, volume 16, issue 4, 2003, Pages 36~43
In this research, the optimization of composite structures was performed using metamodels. The optimization of composite structures requires a lot of time when optimizing the result of the time-consuming analysis. Thus, metamodels are used to replace the time-consuming analysis with simple models. RSM, kriging and neural networks are widely used metamodels. RSM and kriging were used in this study. The ultimate failure load analysis of the composite structure was approximated by metamodels. The optimizations of the composite plate were performed to maximize ultimate failure load using genetic algorithm and metamodels.
Acoustic Emission during Crack Propagation Process of Rubber-Modified Epoxy Resin
Composites Research, volume 16, issue 4, 2003, Pages 44~50
The damage zone around a crack tip occurring before the fracture is a significant domain. which affects the toughening mechanism of materials. In this study. the growth process of damage zone in the vicinity of crack tip for rubber-modified epoxy resin is investigated using an acoustic emission(AE) analysis. The weight fractions of rubber(CTBN 1300
B) in rubber-modified epoxy resin are 5 wt% and 15 wt%. The fracture toughness(
) and the fracture energy(
) were measured using 3 point bending single-edge notched specimens. The damage zone and rubber particles distributed around the crack tip were observed by a polarized optical microscope and an atomic force microscope(AFM). The damage zone around crack tip of rubber-modified epoxy resin was formed at 13 % loading and developed until 57 % loading of the fracture load. The crack initiated at 57 % loading grew repeatedly in the stick-slip propagation behavior. Based on time-frequency analysis, it was confirmed that AE signals with frequency bands of 0.15~0.20 MHz and 0.20~0.30 MHz were generated from cavitation and stable/unstable cracking inside the damage zone.
On-line Cure Monitoring of Adhesive Joints by Dielectrometry
Composites Research, volume 16, issue 4, 2003, Pages 51~58
Since the reliability of adhesively bonded joints is much dependent on the curing status of thermosetting adhesive, the on-line cure monitoring during the cure of adhesively joints could improve the quality of adhesively bonded joints. In this work, the dielectric method which measures the dissipation factor of the adhesive during the cure of joints and converts it into the degree of cure of the adhesive was devised. The relation between the dissipation factor and the degree of cure of adhesive was investigated, which could eliminate the temperature effect on the dissipation factor that is a strong function of the degree of cure and temperature of adhesive. From the investigation, it was found that the dissipation factor showed a trend similar to the cure rate of the adhesive.
FEM Analysis of Smart Skin Structure Specimen
Composites Research, volume 16, issue 4, 2003, Pages 59~65
FEM analysis of the smart skin structure, and application of the sandwich structures investigated. The honeycomb manufactures only provide stillness of thickness direction and transverse shear modulus. Although these are dominant mechanical properties. the other mechanical properties are needed in FEM analysis. Hence, this work shows procedures of obtaining those mechanical properties. Honeycomb material was assumed to be ar, isotropic material and properties are estimated by its dominant honeycomb properties. The other honeycomb properties are then obtained by mechanical properties of Nomex. Buckling test and three point bending test were simulated by ABAQUS. Both the shell and solid element models were used. The results were compared with experimental results and analytical approaches. They showed good agreements. This study shows a guideline of FEM analysis of smart skin structure using commercial a FEM package.
Experimental Investigation on the Behaviour of CFRP Laminated Composites under Impact and Compression After Impact (CAI)
Lee, J ; Kong, C ; Soutis C. ;
Composites Research, volume 16, issue 4, 2003, Pages 66~73
The importance of understanding the response of structural composites to impact and CAI cannot be overstated to develop analytical models for impact damage and CAI strength predictions. This paper presents experimental findings observed from quasi-static lateral load tests, low velocity impact tests. CAI strength and open hole compressive strength tests using 3 mm thick composite plates(
- IM7/8552). The conclusion is drawn that damage areas for both quasi-static lateral load and impact tests are similar and the curves of several drop weight impacts with varying energy levels(between 5.4 J and 18.7 J) follow the static curve well. In addition, at a given energy the peak force is in good agreement between the static and impact cases. It is identified that the failure behaviour of the specimens from the CAI strength tests was very similar to that observed in laminated plates with open holes under compression loading. The residual strengths art: in good agreement with the measured open hole compressive strengths. considering the impact damage site area, an equivalent hole. The experimental findings suggest that simple analytical models for the prediction of impact damage area and CAI strength can be developed on the basis of the failure mechanism observed from the experimental tests.
Nondestructive Microfailure and Interfacial Evaluation of Plasma-Treated PBO and Kevlar Fibers/Epoxy Composites using Micromechanical Test and Acoustic Emission
Composites Research, volume 16, issue 4, 2003, Pages 74~79
Comparison of interfacial properties and microfailure mechanisms of oxygen-plasma treated poly(p-phenylene-2,6-benzobisoxazole(PBO. Zylon) and poly(p-phenylene terephthalamide)(PPTA, Kevlar) fibers/ epoxy composites were investigated using micromechanical technique and nondestructive acoustic emission(AE). Interfacial shear strength(IFSS) and work of adhesion, Wa of PBO or Kevlar fibers/epoxy composites increased by oxygen-plasma treatment. Plasma-treated Kevlar fiber shooed the maximum critical surface tension and polar term, whereas the untreated PBO fiber showed the minimum value. Microfibril fracture pattern of plasma-treated Kevlar fiber appeared obviously. Based on the propagation of microfibril failure toward core region. the number of AE events for plasma-treated PBO and Kevlar fibers increased significantly. The results oi nondestructive AE were consistent well with microfailure modes by optical observation in microdroplet and two-fiber composites tests.
철도차량의 화재예방을 위한 각 국의 F.S.T. 기술 규정과 동향
Composites Research, volume 16, issue 4, 2003, Pages 80~87