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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 20, Issue 6 - Dec 2007
Volume 20, Issue 5 - Oct 2007
Volume 20, Issue 4 - Aug 2007
Volume 20, Issue 3 - Jun 2007
Volume 20, Issue 2 - Apr 2007
Volume 20, Issue 1 - Feb 2007
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Ballistic Resistance Performance of Kevlar Fabric Impregnated with Shear Thickening Fluid
Song, Heung-Sub ; Yoon, Byung-Il ; Kim, Chang-Yun ; Park, Jong-Lyul ; Kang, Tae-Tin ;
Composites Research, volume 20, issue 3, 2007, Pages 1~7
Manufacturing process of the shear thickening fluid(STF) and evaluation of the ballistic penetration resistance performance of the Kevlar-STF composites were studied. STF was made from silica and ethylene glycol, and the Kevlar-STF composite was made by impregnating the STF into the Kevlar fabric. Specimens including neat Kevlar woven fabrics and Kevlar-STF composites with two types of silica were prepared and carried out the ballistic tests. From the results STFs represented shear thickening behavior irrespective of the silica type, and Kevlar-STF composite with spherical silica showed best ballistic penetration resistance performance among them. Especially the specimens of Kevlar-STF composites with spherical silica showed radial fiber deformation by the projectile during the tests, that was somewhat different deformation behavior from those of the neat Kevlar fabrics shown fiber pull-out phenomena or fracture.
Bending Performances and Collapse Mechanisms of Light-weight Aluminum-GERP Hybrid Square Tube Beams
Lee, Sung-Hyuk ; Kim, Hyung-Jin ; Chang, Young-Wook ; Choi, Nak-Sam ;
Composites Research, volume 20, issue 3, 2007, Pages 8~16
Bending collapse of light-weight square tubes used for vehicle structure components is a dominant failure mode in oblique collision and rollover of vehicles. In this paper bending performances of aluminum-GFRP hybrid tube beams were evaluated in relation with bending deformation behavior and energy absorption characteristics. Aluminum/GFRP hybrid tube beams fabricated by inserting adhesive film between prepreg and metal layer were used in the bending test. Failure mechanisms of hybrid tubes under a bending load were experimentally investigated to analyze the bending performance as a function of ply orientation and composite layer thickness. Ultimate bending moments and energy absorption capacity of hybrid tube beams were obtained from the measured load-displacement corves. It was found that aluminum/GFRP hybrid tubes could be converted to rather stable collapse mode showing excellent energy absorption capacity in comparison to the pure aluminum tube beams. In particular, the hybrid tube beam with
composite layer showed a large improvement by about 78% in energy absorption capacity and by 29% in specific energy absorption.
A Study on the Failure Modes of Neat Kevlar Fabric and Kevlar Liquid Armor Impregnated with Shear Thickening Fluid
Yoon, Byung-Il ; Song, Heung-Sub ; Paik, Jong-Gyu ;
Composites Research, volume 20, issue 3, 2007, Pages 17~24
In this study, the failure modes by ballistic impacts were studied both for a neat Kevlar woven fabric and a Kevlar liquid armor impregnated with shear thickening fluid (STF) containing silica particles. These two materials showed quite different failure modes macroscopically in ballistic impacts tests used by Cal.22 FSP and 9mm FMJ bullet. Yarn pull-out for the neat Kevlar woven fabric and yarn fracture occurred partially through all plies from 1st ply to last one for the STF-Kevlar are an important energy absorption mechanisms. The results observed by S.E.M showed commonly fiber damage which are torn skin in the longitudinal fiber direction, fiber split axially and fiber fracture for two materials. The reasons why STF-kevlar liquid armor material exhibits excellent ballistic performance are as follow: firstly the increased friction forces between yarn-yarn and fabric-fabric covered with silica particles and secondary the evolution of shear thickening phenomenmon resulting in suppression of yarn mobility.
Design and fabrication of Smart Skin Antenna for Phased Array Applications
Son, Seong-Ho ; Hwang, Woon-Bong ;
Composites Research, volume 20, issue 3, 2007, Pages 25~30
This paper describes the basic design and fabrication of smart skin antenna for phased array applications. The smart skin phased array antenna, of which radiation pattern can be electrically steerable without mechanical rotation, has to meet the both mechanical and electrical performance. The smart skin antenna is a honeycomb sandwich structure to enhance the mechanical performance such as strength, weight and so on. The example of smart skin antenna integrated with radome is designed with the resonant frequency of 5 GHz, circular polarization, 2 by 2 subarray, and a coaxial probe-fed excitation. In addition, the performance of raw microstrip patch antenna uncovered radome is investigate. The fabricated smart skin antenna shows a reasonable performance with gain of 12.2 dBi and frequency bandwidth of 6.4 %.
Quantitative Nondestructive Evaluation in Composite Beam Using Piezoelectric Transducers
Lee, Sang-Hyoup ; Choi, Young-Geun ; Kim, Sang-Tae ;
Composites Research, volume 20, issue 3, 2007, Pages 31~36
A quantitative prediction method for initial crack length in a carbon/epoxy (CF/EP) composite beam using active piezoelectric transducers was established in this study. Wavelet Transform (WT)-based signal processing and identification technique in time-frequency domain was developed to facilitate the determination of damage presence and severity. Dynamic response of a CF/EP composites beam containing a continuously expanding crack, coupled with a pair of active piezoelectric disks, was examined under a narrow band excitation, and then applied with the proposed signal processing technique.
Evaluation on Thermal Shock Damage of Smart Composite using Nondestructive Technique
Lee, Jin-Kyung ; Park, Young-Chul ; Lee, Kyu-Chang ; Lee, Joon-Hyun ;
Composites Research, volume 20, issue 3, 2007, Pages 37~42
Tensile residual stress is occurred by difference of coefficients of thermal expansion between fiber and matrix is one of the serious problems in metal matrix composite(MMC). TiNi alloy fiber was used to solve the problem of the tensile residual stress as the reinforced material. TiNi alloy fiber improves the tensile strength of composite with occurring of compressive residual stress in the matrix by its shape memory effect. A hot press method was used to create the optimal fabrication condition for a Shape Memory Alloy(SMA) composite. The bonding effect of the matrix and the reinforcement within the SMA composite by the hot press method was strengthened by cold rolling. In addition, acoustic emission technique was used to quantify the microscopic damage behavior of cold rolled TiNi/A16061 shape memory alloy composite at low temperature. The damage degree for the specimen that underwent thermal shock cycles was also discussed.
Effects of Transverse Shear Deformation and Rotary Inertia on Vibration of Rotating Polar Orthotropic Disks
Kim, Dong-Hyun ; Koo, Kyo-Nam ;
Composites Research, volume 20, issue 3, 2007, Pages 43~49
Dynamic instability of rotating disks is the most significant factor to limit its rotating speed. Application of composite materials to rotating disks may enhance the dynamic stability leading to a possible design of rotating disks with lightweight and high speed. Whereas much work has been done on the effect of transverse shear and rotary inertia, called Timoshenko effect, on the dynamic behavior of plates, there is little work on the correlation between the effect and the rotation of disk, especially nothing in case of composite disks. The dynamic equations of a rotating composite disk are formulated with the Timoshenko effect and the vibrational analysis is performed by using a commercial package MSC/NASTRAN. According to the results, the Timoshenko effect goes seesaw in some modes, unlike the well-known fact that the effect decreases as the rotating speed increases. And it can be concluded, based only on the present results, that decrement of the Timoshenko effect by disk rotation grows larger as the thickness ratio decreases, the diameter ratio increases, the modulus ratio increases, and the mode number increases.
A Study on Mechanical Properties of IPMC actuators
Kim, Hong-Il ; Kim, Dae-Kwan ; Han, Jae-Hung ;
Composites Research, volume 20, issue 3, 2007, Pages 50~54
The Ionic Polymer Metal Composite (IPMC), an electro-active polymer, has many advantages including bending actuation, low weight, low power consumption, and flexibility. These advantages coincide with the requirements of a bio-related application. Thus, IPMC is promising materials for bio-mimetic actuator and sensor applications. Before applying IPMC to actual application, basic mechanical properties of IPMC should be studied in order to utilize IPMC for practical uses. Therefore, IPMCs are fabricated to investigate the mechanical characteristics. Nafion is used as a base ionic polymer. Mason samples cast with various thicknesses are used to test the thickness effects of IPMC. Subsequently, IPMC is fabricated using the chemical reduction method. The deformation, blocking force and frequency response of the IPMC actuator are important properties. In this present study, the performances of the IPMC actuators, including the deformation, blocking force and natural frequency, are then obtained according to only the input voltage and IPMC dimensions. Finally, the empirical performance model and the equivalent stiffness model of the IPMC actuator are established using experiments results.
Interfacial and Durability Evaluation of Jute and Hemp Fiber/Polypropylene Composites Using Micromechanical Test and Acoustic Emission
Kim, Pyung-Gee ; Jang, Jung-Hoon ; Kim, Sung-Ju ; Hwang, Byung-Sun ; Park, Joung-Man ;
Composites Research, volume 20, issue 3, 2007, Pages 55~62
Interfacial evaluation and durability of Jute and Hemp fibers/polypropylene (PP) composites were investigated. Moisture content of various treated conditions were measured by thermogravimetic analyzer (TGA). After boiling water test, mechanical properties and IFSS between Jute, Hemp fibers and PP matrix decreased. On the other hand, work of adhesion increased due to swelled fibril by water. Surface energies of Jute and Hemp fibers before and after boiling water test were obtained using dynamic contact angle measurement. IFSS was not always consistent with thermodynamic work of adhesion. In boiling water case, since Jute and Hemp fibers could be swelled by water, surface area and moisture infiltration space increased. Environmental effect on microfailure modes of Jute or Hemp fibers and Jute or Hemp fibers/PP composites were obtained by observing via optical microscope and by monitoring acoustic emission (AE) events and their AE parameters. After boiling water test, unlike Hemp fiber, microfailure process of Jute fiber could occur due to low tensile strength by swelled fibril. In addition, AE events occurred more and AE amplitude and energy became lower than those of before boiling water test.
Structural and Dynamic Analysis of Mineral/glass Reinforced Polypropyolene Compound Automotive Engine Cover
Kim, Beom-Keun ; Kim, Heung-Seob ; Kim, Yong-Su ; Cho, Gyu-Chul ; Jeong, Jae-Kwan ;
Composites Research, volume 20, issue 3, 2007, Pages 63~66
Structural analysis of automotive engine cover under vibration excitation is performed by finite element analysis (FEA) in order to identify the critical area of the structure. Assembly load due to the tightening of the bolts as well as the vibration excitation were considered to describe the actual loading condition. Natural frequencies of the system were extracted considering the damping effect of the structure. Dynamic analysis was performed based on the extracted natural frequency of the system. Experimental modal analysis (EMA) and measurement of strains were performed to verify the results of the analysis. Analysis results correlated closely with the experimental results. Analysis and experiments showed that contribution of the assembly load should not be ignored to predict the structural failure of the engine cover.