Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal Basic Information
Journal DOI :
The Korean Society for Composite Materials
Editor in Chief :
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
Probabilistic Fiber Strength of Composite Pressure Vessel
Composites Research, volume 16, issue 6, 2003, Pages 1~9
In this paper, probabilistic failure analysis based on Weibull distribution function is proposed to predict the fiber strength of composite pressure vessel. And, experimental tests were performed using fiber strand specimens, unidirectional laminate specimens and composite pressure vessels to confirm the volumetric size effect on the fiber strength. As an analytical method, the Weibull weakest link model and the sequential multi-step failure model are considered and mutually compared. The volumetric size effect shows the clearly observed tendency towards fiber strength degradation with increasing stressed volume. Good agreement of fiber strength distribution was shown between test data and predicted results for unidirectional laminate and hoop ply in pressure vessel. The site effect on fiber strength depends on material and processing factors, the reduction of fiber strength due to the stressed volume shows different values according to the variation of material and processing conditions.
Experimental Study of the Microvoids formation and Transport in the Vacuum Assisted Resin Transfer Molding Process
Se Won Eun ; Woo Il Lee ;
Composites Research, volume 16, issue 6, 2003, Pages 10~15
In RTM process, the content of microvoids can be critical due to the fact that the presence of microvoids degrades mechanical properties on the fabricated composite parts. The present paper proposes an experimental method of observation in void formation and transport. VARTM processes are performed under observation with a digital video camera and then the microvoid formation in the flow front and transport are videotaped and observed both in channels and tows. The obtained data are used in the mathematical model in order to determine the model constants. Experimental results and expected results from the mathematical model show a good agreement with each other.
A study on the acoustic emission characteristics of laminated composite structures
Composites Research, volume 16, issue 6, 2003, Pages 16~22
This paper studied the AE(acoustic emission) characteristics of the laminated composite structures. The composite stiffened panels under the compressive loading emitted various AE signals when they buckled or changed the buckling modes. In addition, the failure initiated and propagation generated a lot of complex signals. From the continuous signal generation. we identified when the failures initiated and whether they propagated or not. The single lap joint of laminated plates under tensional load also generated AE signals when bonding region failed. The first failure occurrence and its propagation are monitored by generated AE signals. The characteristics of AE signals used in this analysis are cumulative hits, hit distribution, peak frequency of generated AE waveform and amplitude of signals. The analysis of AE signals shows that continuous increment of cumulative hits can be regarded as damage propagation and three dominant peak frequencies can correspond to typical failure modes in the laminated composites.
Estimation of Dynamic Response of Advanced Composite Material Decks for Bridges Application under Various Vehicle Driving Velocities
Composites Research, volume 16, issue 6, 2003, Pages 23~32
Applications of advanced composite material in construction field are tending upwards and development of all composite material bridges is making progress rapidly in home and abroad due to their high strength to weight ratio. This paper formulated the dynamic responses of the laminated composite structures subjected to moving load and analyzed the various dynamic behaviors using the finite element method. The nondimensionalized natural frequencies of a simply supported square-laminated composite plate are considered for verifications. Mode superposition and Newmark direct integration method are applied for moving load analysis. For structural models, dynamic magnification factor calculated for various velocities of the moving load and displacements characteristics of laminated composite structures due to the moving load are investigated theoretically Numerical results are presented to study the effects of lamination scheme, stacking sequence, and fiber angle for laminated composite structures during moving load. The various results on moving load and lamination through numerical analysis will present an important basic data for development and grasp the behavior of all composite material bridges.
The Evaluation of the thermal degradation and the degree of cure of glass/epoxy composite by ultrasonic technique
Composites Research, volume 16, issue 6, 2003, Pages 33~40
The initial thermal degradation of polymer matrix composite is not observed easily. At the beginning of thermal degradation of polymer matrix composites, phase transformation such as chain scission, oxidation occur, and then micro delamination is produced in matrix and interface between matrix and fiber before blistering. Initial heat damage deteriorate mechanical properties of composites. We presented the detection method of the initial heat damage of composites conveniently using ultrasonic technique. Absorption coefficient and material velocity was measured with thermal degradation and degree of cure. The more thermal degradation was progressed, the more absorption coefficient was increased. When the cure temperature is more high, the absorption coefficient of cured composite is increased and material velocity is decreased. We concluded that cure temperature is more high, the defects such as void is increased and molecular structure cured at high temperature has cross-linking structure which is more absorb the ultrasonic waves.
Measurement of Material Properties of Composites under High Temperature using Fiber Bragg Grating Sensors
Composites Research, volume 16, issue 6, 2003, Pages 41~47
Composites are widely used for aircraft, satellite and other structures due to its good mechanical and thermal characteristics such as low coefficient of thermal expansion(CTE), heat-resistance, high specific stiffness and specific strength. In order to use composites under condition of high temperature, however, material properties of composites at high temperatures must be measured and verified. In this paper, material properties of T700/Epoxy were measured through tension tests of composite specimens with an embedded FBG sensor in the thermal chamber at the temperatures of RT,
. Through the pre-test of an embedded optical fiber, we confirmed the embedding effects of an optical fiber on material properties of the composites. Two kinds of specimens of which stacking sequences are [0/｛0｝/0]
. and [
]. were fabricated. From the experimental results, material property changes of composites were successfully shown according to temperatures and we confirmed that fiber Bragg grating sensor is very appropriate to strain measurement of composites under high temperature.
The effect of random spectrum on the fatigue life of hybrid metal matrix composites
Composites Research, volume 16, issue 6, 2003, Pages 48~55
This research makes comparisons of empirical fatigue-lives between AC8A A1 alloy and the metal matrix composites(A1/A12O3, A1/A12O3/A12O3p), and also includes comparisons of fatigue-lives between empirical fatigue-lives and estimated fatigue-lives from regular-periodic load testing, AE method to predict fatigue-crack initiation before visible in sight and SEM(scanning electron microscope) photographs of each material. According to the test results of the notched specimen. the fatigue life of the hybrid metal matrix composites and the metal matrix composites, which are more brittle than the base matrix was shorter than that of the base matrix under both types of loads. In addition, the fatigue-life estimated from the damage summation method and that from experiments at random loads were fairly identical.
광섬유 센서를 이용한 원자력 발전소 격납구조물의 가동전 가압 팽창을 통한 구조건전성 시험
Composites Research, volume 16, issue 6, 2003, Pages 56~61
In this Paper, a fiber Bragg grating(FBG) sensor system is described and FBGs are well-suited for long term and extremely severe experiments, where traditional strain gauges fail. In the system. a reflect wave-length measurement method which employs a tunable light source to find out the center wave-length of FBG sensor is used. We apply the FBG system to nuclear energy Power Plant for structural integrity test to measure the displacement of the structure under designed pressure and to check the elasticity of the structure by measuring the residual strain. The system works very well and it is expected that it can be used for a real-time strain, temperature and vibration detector of smart structure.
Composites Research, volume 16, issue 6, 2003, Pages 62~64