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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 24, Issue 6 - Dec 2011
Volume 24, Issue 5 - Oct 2011
Volume 24, Issue 4 - Aug 2011
Volume 24, Issue 3 - Jun 2011
Volume 24, Issue 2 - Apr 2011
Volume 24, Issue 1 - Feb 2011
Selecting the target year
Experimental and Numerical Studies on Composite Tubes for the Energy Absorber of High-speed Train
Nguyen, Cao-Son ; Jang, Hong-Kyu ; Shin, Jae-Hwan ; Son, Yu-Na ; Kim, Chun-Gon ;
Composites Research, volume 24, issue 1, 2011, Pages 1~9
DOI : 10.7234/kscm.2011.24.1.001
This paper presents an experimental and numerical study on composite tubes for the energy absorber of the high-speed train. The purpose of the experimental study is to find out which lay-up is the best lay-up for the energy absorber. Four lay-ups were tested using quasi static method:
. Two triggering methods were used to create initial damage and guarantee the progressive collapse mode: bevel edge and notch edge. As a result,
lay-up was find out the best lay-up among the laminates being tested. In the numerical study, a parametric analysis was done to find out the most proper way to simulate the quasi static test of a composite tube using LS-DYNA program. A single composite tube was modeled to be crashed by a moving wall. Comparison between simulation and experiment was done. Reasonable agreement between experiment and analysis was obtained. Dealing with parameter TFAIL and the mass scaling factor, this parametric study shows the ability and the limitation of LS-DYNA in modeling the quasi static test for the composite tube.
Prediction of Fatigue life of Composite Laminates using Micromechanics of Failure
Jin, Kyo-Kook ; Ha, Sung-Kyu ; Kim, Jae-Hyuk ; Han, Hoon-Hee ;
Composites Research, volume 24, issue 1, 2011, Pages 10~16
DOI : 10.7234/kscm.2011.24.1.010
Many tests are required to predict the fatigue life of composite laminates made of various materials and having different layup sequences. Aiming at reducing the number of tests, a methodology was presented in this paper to predict fatigue life of composite laminates based on fatigue life prediction of constituents, i.e. the fiber, matrix and interface, using micromechanics of failure. For matrix, the equivalent stress model which is generally used for isotropic materials was employed to take care of multi-axial fatigue loading. For fiber, a maximum stress model considering only stress along fiber direction was used. The critical plane model was introduced for the interface of the fiber and matrix, but fatigue life prediction was ignored for the interface since the interface fatigue strength was presumed high enough. The modified Goodman equation was utilized to take into account the mean stress effect. To check the validity of the theory, the fatigue life of three different GFRP laminates, UDT[
]S and TX[
]S was examined experimentally. The comparison between predictions and test measurements showed good agreement.
Failure of composite sandwich joints under pull-out loading
Park, Yong-Bin ; Yang, Hyeon-Jeong ; Kweon, Jin-Hwe ; Choi, Jin-Ho ; Cho, Hyun-Il ;
Composites Research, volume 24, issue 1, 2011, Pages 17~23
DOI : 10.7234/kscm.2011.24.1.017
The failure of composite sandwich joints was experimentally investigated. A total of 30 joint specimens of 5 different types were tested with various fastening methods and core materials. In the NomexTM core sandwich joints, the core shear buckling was commonly observed in all the specimens which was followed by the slope change of the load-displacement curve. After the shear buckling, however, the joints carried additional loads of 50~200% over the buckling loads and then finally failed in the upper face breakage. The joints of PMI foam core showed the shear failure of the core instead of shear buckling and experienced the sharp drop of the carried load. Considering the failure modes, while both the core and face properties are important in the
core joints, core shear strength seems to be the critical factor for the foam core joints.
Impact Monitoring of Composite Structures using Fiber Bragg Grating Sensors
Jang, Byeong-Wook ; Park, Sang-Oh ; Lee, Yeon-Gwan ; Kim, Chun-Gon ; Park, Chan-Yik ; Lee, Bong-Wan ;
Composites Research, volume 24, issue 1, 2011, Pages 24~30
DOI : 10.7234/kscm.2011.24.1.024
Low-velocity impact can cause various damages which are mostly hidden inside the laminates or occur in the opposite side. Thus, these damages cannot be easily detected by visual inspection or conventional NDT systems. And if they occurred between the scheduled NDT periods, the possibilities of extensive damages or structural failure can be higher. Due to these reasons, the built-in NDT systems such as real-time impact monitoring system are required in the near future. In this paper, we studied the impact monitoring system consist of impact location detection and damage assessment techniques for composite flat and stiffened panel. In order to acquire the impact-induced acoustic signals, four multiplexed FBG sensors and high-speed FBG interrogator were used. And for development of the impact and damage occurrence detections, the neural networks and wavelet transforms were adopted. Finally, these algorithms were embodied using MATLAB and LabVIEW software for the user-friendly interface.
Effect of Combined Environmental Factors on Adhesive Shear Strengths and Chemical Structures of Adhesives
Hwang, Young-Eun ; Yoon, Sung-Ho ;
Composites Research, volume 24, issue 1, 2011, Pages 31~36
DOI : 10.7234/kscm.2011.24.1.031
Adhesive shear strengths of the established adhesives and the alternative adhesives were evaluated and their chemical structures were analyzed in order to investigate the possibility of replacing the established adhesives with the alternative adhesives applicable to the seeker for the guided missiles. Two types of the adhesives such as the structural adhesives and the sealant adhesives were considered. Those adhesives were exposed to the combined environmental factors consisting of temperature, moisture and ultraviolet over 1000 hours. Adhesive shear test was conducted to evaluate adhesive shear strengths and ATR FT-IR was utilized to investigate chemical structures. According to the results, the adhesive shear strengths of the alternative adhesives revealed higher than those of the established adhesives. Also the alternative adhesives were more stable to the combined environmental condition than the established adhesives. Therefore, it is found that the established adhesives were able to be replaced by the alternative adhesives.
Thermal Residual Stresses in the Frequency Selective Surface Embedded Composite Structures and Design of Frequency Selective Surface
Kim, Ka-Yeon ; Chun, Heoung-Jae ; Kang, Kyung-Tak ; Lee, Kyung-Won ; Hong, Ic-Pyo ; Lee, Myoung-Keon ;
Composites Research, volume 24, issue 1, 2011, Pages 37~44
DOI : 10.7234/kscm.2011.24.1.037
In this paper, Particle Swarm Optimization(PSO) is applied to the design of the Frequency Selective Surface(FSS) and residual stresses of hybrid radome is predicted. An equivalent circuit model with Square Loops arrays was derived and then PSO was applied for acquiring the optimized geometrical parameters with proper resonant frequency. Residual stresses occur in the FSS embedded composite structures after cocuring and have a great influence on the strength of the FSS embedded composite structures. They also effect transmission quality because of delamination. Therefore, the thermal residual stresses of FSS embedded composite structures were analyzed using finite element analysis with considering the effects of FSS pattern, and composite stacking sequence.
Interfacial Control of Multi-functional CNT and ITO/PET Nanocomposites having Self-Sensing and Transparency
Wang, Zuo-Jia ; Kwon, Dong-Jun ; Gu, Ga-Young ; Park, Joung-Man ;
Composites Research, volume 24, issue 1, 2011, Pages 45~50
DOI : 10.7234/kscm.2011.24.1.045
Transparent and conductive carbon nanotube on polyethylene terephthalate (PET) were prepared by dip-coating method for self-sensing multi-functional nanocomposites. The changes in the electrical and optical properties of CNT coating mainly depended on the number of dip-coating, concentration of CNT solution. Consequently, the surface resistance and transmittance of CNT coating were sensitively controlled by the processing parameters. Surface resistance of CNT coating was measured using four-point method, and surface resistance of coated CNT could be better calculated by using the dual configuration method. Optical transmittance of PET film with CNT coating was evaluated using UV spectrum. Surface properties of coated CNT investigated by wettability test via static and dynamic contact angle measurement were consistent with each other. As dip-coating number increased, surface resistance of coated CNT decreased seriously, whereas the transmittance exhibited little lower due to the thicker CNT networks layer. Interfacial microfailure properties were investigated for CNT and indium tin oxide (ITO) coatings on PET substrates by electrical resistance measurement under cyclic loading fatigue test. CNT with high aspect ratio exhibited no change in surface resistance up to 2000 cyclic loading, whereas ITO with brittle nature showed a linear increase of surface resistance up to 1000 cyclic loading and then exhibited the level-off due to reduced electrical contact points based on occurrence of many micro-cracks.