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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 29, Issue 4 - Aug 2016
Volume 29, Issue 3 - Jun 2016
Volume 29, Issue 2 - Apr 2016
Volume 29, Issue 1 - Feb 2016
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Evaluation of Fracture Behavior of Adhesive Layer in Fiber Metal Laminates using Cohesive Zone Models
Lee, Byoung-Eon ; Park, Eu-Tteum ; Ko, Dae-Cheol ; Kang, Beom-Soo ; Song, Woo-Jin ;
Composites Research, volume 29, issue 2, 2016, Pages 45~52
DOI : 10.7234/composres.2016.29.2.045
An understanding of the failure mechanisms of the adhesive layer is decisive in interpreting the performance of a particular adhesive joint because the delamination is one of the most common failure modes of the laminated composites such as the fiber metal laminates. The interface between different materials, which is the case between the metal and the composite layers in this study, can be loaded through a combination of fracture modes. All loads can be decomposed into peel stresses, perpendicular to the interface, and two in-plane shear stresses, leading to three basic fracture mode I, II and III. To determine the load causing the delamination growth, the energy release rate should be identified in corresponding criterion involving the critical energy release rate (
) of the material. The critical energy release rate based on these three modes will be
. In this study, to evaluate the fracture behaviors in the fracture mode I and II of the adhesive layer in fiber metal laminates, the double cantilever beam and the end-notched flexure tests were performed using the reference adhesive joints. Furthermore, it is confirmed that the experimental results of the adhesive fracture toughness can be applied by the comparison with the finite element analysis using cohesive zone model.
Failure Pressure Prediction of Composite T-Joint for Hydrodynamic Ram Test
Kim, Dong-Geon ; Go, Eun-Su ; Kim, In-Gul ; Woo, Kyung-Sik ; Kim, Jong-Heon ;
Composites Research, volume 29, issue 2, 2016, Pages 53~59
DOI : 10.7234/composres.2016.29.2.053
Aircraft wing structure is used as a fuel tank containing the fluid. Fuel tank and joint parts are consists of composite structure. Hydrodynamic Ram(HRAM) effect occurs when the high speed object pass through the aircraft wing or explosion and the high pressure are generated in the fuel tank by HRAM effect. High pressure can cause failure of the fuel tank and the joint parts as well as the aircraft wing structure. To ensure the aircraft survivability design, we shall examine the behavior of the joint parts in HRAM effect. In this study, static tensile tests were conducted on four kind of the composite T-Joints. The failure behavior of the composite T-joint was examined by strain gauges and high speed camera. We examine the validity of the Finite Element Modeling by comparing the results of FEA and static tensile tests. The failure stresses and failure pressure of the composite T-Joint were calculated by FEA.
Experimental Study on the Structural Integrity of Type IV Hydrogen Pressure Vessels Experienced Impact Loadings
Han, Min-Gu ; Jung, Kyung-Chae ; Chang, Seung-Hwan ;
Composites Research, volume 29, issue 2, 2016, Pages 60~65
DOI : 10.7234/composres.2016.29.2.060
In this paper, finite element analysis and real time monitoring experimental work using FBG sensor were carried out for analyzing structural integrity of a Type IV hydrogen pressure vessel under impact loading condition. By using finite element analysis with the ply based modeling technique, sensor insertion points and pressure condition were suggested. Tensile test with an angle ply specimen was conducted for getting the reliability of FBG sensor insertion method. After fabricating the vessel, total five times pressurization fatigue tests were conducted (Non-impact pressurization: 1, After impact pressurization: 4). Experimental results revealed that filling cycle time was gradually increased and filling gradient was decreased when the vessel experienced impact.
Micromechanical Computational Analysis for the Prediction of Failure Strength of Porous Composites
Yang, Dae Gyu ; Shin, Eui Sup ;
Composites Research, volume 29, issue 2, 2016, Pages 66~72
DOI : 10.7234/composres.2016.29.2.066
Porosity in polymer matrix composites increases rapidly during thermochemical decomposition at high temperatures. The generation of pores reduces elastic moduli and failure strengths of composite materials, and gas pressures in internal pores influence thermomechanical behaviors. In this paper, micromechanical finite element analysis is carried out by using two-dimensional representative volume elements for unidirectionally fiber-reinforced composites with porous matrix. According to the state of the pores, effective elastic moduli, poroelastic parameters and failure strengths of the overall composites are investigated in detail. In particular, it is confirmed that the failure strengths in the transvers and through-thickness directions are predicted much more weakly than the strength of nonpored matrix, and decrease consistently as the porosity of matrix increases.
Evaluation of the Impact Behavior of Inline Disk Wheel Made of Carbon Fiber Reinforced Composites
Kwon, Hye-In ; Lee, Sang-Jin ; Shin, Kwang-Bok ;
Composites Research, volume 29, issue 2, 2016, Pages 73~78
DOI : 10.7234/composres.2016.29.2.073
In this paper, The concept of a wheel with carbon fiber composite is to replace the conventional material used for a wheel hub, such as plastic, with a disk-type hub made of carbon fabric and epoxy resin. The impact load from the ground under real conditions was considered; a low-velocity impact test was conducted to evaluate the impact performance of the carbon wheel and compare it with that of a conventional plastic wheel. This study applied a 70 J impact load as a test condition. The impact energy was controlled in the test by adjustment of height and weight of impactor. The use of a carbon disk wheel hub was confirmed to reduce weight and generate an excellent repulsive force at low energy under conditions similar to real driving conditions. The results showed that the maximum load increased proportionally depending on the impact load, but the growth of the maximum load was reduced at a 20 J impact load and tended to decrease at a 45 J impact load. The carbon wheel showed excellent properties ; the level of rebounding was 35.3% and 19.1% of the total impact energy at impact loads of 5 J and 10 J, respectively. On the other hand, the carbon disk wheel rebounded less than 5% of the total energy due to crack generation of the thin carbon hub for impact loads of more than 20 J.
Comparison of Mechanical and Interfacial Properties on Chemical Structures of Acrylic and Epoxy Adhesives
Shin, Pyeong-Su ; Kim, Jong-Hyun ; Choi, Jin-Yeong ; Kwon, Dong-Jun ; Lee, Sang-Il ; Park, Joung-Man ;
Composites Research, volume 29, issue 2, 2016, Pages 79~84
DOI : 10.7234/composres.2016.29.2.079
An adhesive can be used to connect two different materials in structures. In comparing with other connecting methods, such as bolt, rivet, and hot melting, the adhesive does not need to use them. It leads to reduce the weight and decrease the stress concentration along the connecting line. This work studied the comparison of mechanical and interfacial properties of commonly-used two adhesives, acrylic type and bisphenol-A epoxy type. Tensile and flexural strength of neat adhesives were also compared. Lap shear test of two adhesives was deduced from the measurement of tensile and fatigue tests. After testing, the failure patterns of adhesive surfaces were observed by a microscope. Tensile strength and mechanical fatigue resistance at using bisphenol-A epoxy adhesive were better than acrylic adhesive. Also adding CNT reinforcement in epoxy adhesive can anticipate mechanical improvement.
An Investigation on the Behavior of Fracture Mechanics as the Type of Mode I at Specimen Bonded with Tapered Carbon Fiber Reinforced Plastic
Lee, Jung-Ho ; Cho, Jae-Ung ; Cheon, Seong Sik ;
Composites Research, volume 29, issue 2, 2016, Pages 85~89
DOI : 10.7234/composres.2016.29.2.085
This paper aims at estimating the fracture behavior at the bonded part of composite material. CFRP is manufactured as the type of TDCB. The static analysis of Mode 1 due to the configuartion factor of m is carried out. Four kinds of specimens have the configuartion factor(m) of 2, 2.5, 3 and 3.5. As the study result, the displacements at specimens are shown to be similar each other in these four cases. At m of 3.5, the reaction force becomes highest as 412 N and is shown to be improved as much as 14% by comparing m of 2. The data on defection of the bonded interface and reaction force are thought to be contributed to the structural design of CFRP and the safe design.