• Journal of the Korean Society of Safety
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• v.17 no.4
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• pp.31-37
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• 2002

This paper demonstrates the analyses of the interlaminar shear stress of laminated composite plates subjected to transversely impact. For this purpose, a plate finite element model based on the higher order shear deformation plate theory in conjunction with static contact laws is developed. Test materials were CFRP with cross-ply laminate $[O_4/{\theta}_4]_S$, $[90_4/{\theta}_4]_S$ stacking sequences and angle-ply laminate $[{\theta}_4/-{\theta}_4]_S$, $[{\theta}_4/-{\theta}_4]_S$ stacking deguences with $2^t{\times}40^w{\times}100^l(mm)$ dimension. As a result, stacking seguence and fiber orientation were found to have a significant effect on the interlaminar stresses in composite laminates.

• International Journal of Ocean System Engineering
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• v.3 no.3
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• pp.152-157
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• 2013

This study, a new concept design of the stem and aims to determine the suitability of various carbon/PEEK composite designs for artificial hip joints. Shear stress tested with alternative materials of the Ti-based stem for artificial hip joints. In addition, FEA is conducted according to the fiber ply orientation and the load condition for carbon/PEEK composites. The stem shape of two types was designed through the shape normal of the femur. Multidirectional load cases were used for each FEA model. In the case of general shape, the results show that the stress of ply orientation case II was lower than for cases I and III. On the other hand, in the case of the curved shape, ply orientation case I was lowest. In the case of the Ti stem, the stress of the curved shape was 18% lower than the general shape.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.3
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• pp.210-220
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• 2001

This paper aims at the evaluation on the characterization of CFRP laminate plates using falling weight impact tester. The experimentation was conducted on several laminates of different fiber and ply orientation. A system was built for the impact strength of CFRP laminates in consideration of stress wave propagation with using drop-weight impact tester as one of impact test. Absorbed energy of orthotropic composites with using T300 fiber, which are composed of the same fiber and stacking number is higher than that or quasi-isotropic specimen over impact energy 7J, but in case or using T700 fiber, much difference does not show. Also, absorbed energy of orthotropic composites with using T300 fiber, which are composed or stacking number and orientation became more than that of T700 fiber specimen; however great change doesn't show in case of quasi-isotropic specimens. It is found that influence was confirmed between impact energy and absorbed energy as the impact energy is increased with adding the falling weight.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.4
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• pp.149-157
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• 2002

This paper is to investigate collapse mechanisms of CFRP(Carbon Fiber Reinforced Plastics)composite tubes and to evaluate collapse characteristics on the change of interlaiminar number and ply orientation angle of outer under static and impact axial compression loads. When a CFRP composite tube is crushed, static/impact energy is consumed by friction between the loading plate and the splayed fronds of the tube, by fracture of the fibers, matrix and their interface. These are associated with the energy absorption capability. In general, CFRP tube with 6 interlaminar number(C-type), absorbed more energy than other tubes(A, B, D-types). The maximum collapse load seemed to increase as the interlaminar number of such tubes increases. The collapse mode depended upon orientation angle of outer of CFRP tubes and loading status(static/impact). Typical collapse modes of CFRP tubes are wedge collapse mode, splaying collapse mode and fragmentation collapse mode. The wedge collapse mode was shown in case of CFRP tubes with 0° orientation angle of outer under static and impact loadings. The splaying collapse mode was shown in only case of CFRP tubes with 90°orientation angle of outer under static loadings, however in Impact tests those were collapsed in fragmentation mode .

• Journal of the Korean Society for Precision Engineering
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• v.18 no.11
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• pp.34-41
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• 2001

This study is to investigate the energy absorption characteristics of CFRP(Carbon-Fiber Reinforced Plastics) tubes on static and dynamic tests. Axial static compression tests have been carried out using the static testing machine(Shin-gang buckling testing machine) and dynamic compression tests have been utilized using an vertical crushing testing machine. When such tubes are subjected to crushing loads, the response is complex and depends on the interaction between the different mechanisms that could control the crushing process. The collapse characteristics and energy absorption have been examined for various tubes. Energy absorption of the tubes are increased as changes in the lay-up which may increase the modulus of tubes. The results have been varied significantly as a function of ply orientation and interlaminar number.

• Steel and Composite Structures
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• v.18 no.3
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• pp.583-601
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• 2015

In the present study, the combined effects of thermal and mechanical loadings on the interlaminar shear stresses of both moderately thin and thick composite laminated beams are numerically analyzed. The finite element modelling of laminated composite beams and analysis of interlaminar stresses are performed using the commercially available software package MSC NASTRAN/PATRAN. The validity of the finite element analysis (FEA) is demonstrated by comparing the experimental test results obtained due to mechanical loadings under the influence of thermal environment with those derived using the present FEA. Various parametric studies are also performed to investigate the effect of thermal loading on interlaminar stresses generated in symmetric, anti-symmetric, asymmetric, unidirectional, cross-ply, and balanced composite laminated beams of different stacking sequences with identical mechanical loadings and various boundary conditions. It is shown that the elevated thermal environment lead to higher interlaminar shear stresses varying with the stacking sequence, length to thickness ratio, ply orientations under identical mechanical loading and boundary conditions of the composite laminated beams. It is realized that the magnitude of the interlaminar stresses along xz plane is always much higher than those of along yz plane irrespective of the ply-orientation, length to thickness ratios and boundary conditions of the composite laminated beams. It is also observed that the effect of thermal environment on the interlaminar shear stresses in carbon-epoxy fiber reinforced composite laminated beams are increasing in the order of symmetric cross-ply laminate, unidirectional laminate, asymmetric cross-ply laminate and anti-symmetric laminate. The interlaminar shear stresses are higher in thinner composite laminated beams compared to that in thicker composite laminated beams under all environmental temperatures irrespective of the laminate stacking sequence, ply-orientation and boundary conditions.

• Steel and Composite Structures
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• v.22 no.6
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• pp.1281-1299
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• 2016

This paper deals with the analysis of vibration of antisymmetric angle-ply plates using spline method for higher order shear theory. Free vibration of laminated plates is addressed to show the capability of the present method in the vicinity of higher order shear deformation theory and simply supported edges of plates. The coupled differential equations are obtained in terms displacement and rotational functions. These displacement and rotational functions are approximated using cubic and quantic spline. A generalized eigenvalue problem is obtained and solved numerically for an eigenfrequency parameter and an associated eigenvector of spline coefficients. The antisymmetric angle-ply fiber orientation are taken as design variables. Numerical results enable us to examine the frequencies for various geometric and material parameters and accuracy and effectiveness of the proposed method is also verified by comparative study.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.560-565
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• 2007

Motivated by needs such as those in the aerospace industry, this paper demonstrates ability to significantly increase buckling loads of perforated composite laminated plates by synergizing FEM and a genetic optimization algorithm (GA). Plate geometry is discretized into specially-developed 3D degenerated eight-node shell isoparametric layered composite elements. General shell theory, involving incremental nonlinear finite element equilibrium equation, is employed. Fiber orientation within individual plies of each element is controlled independently by the genetic algorithm. Eigen buckling analysis is performed using the subspace iteration method. Available results demonstrate the approach is superior to more conventional methodologies such as modifying ply thickness or the stacking sequence of individual rectilinear plies having common fiber orientation through the plate.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.7 s.94
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• pp.1761-1771
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• 1993

In this paper, the design of thick laminated composite plate subjected to thermal buckling load under uniform temperature distribution is presented. In the design procedures of composite laminated plates for maximum thermal buckling load. the finite element method based on shear deformed theory is used for the analysis or laminated plates. One-demensional search method is used to find optimal fiber orientation and, in the next step, optimal thickness is investigated. Design variables such as fiber orientation and ply thicknesses coefficient of plates are adopted. The optimal design for the symmetric or antisymmetric laminated plates consisted of 4 layers with maximum thermal buckling load is performed.

• Tribology and Lubricants
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• v.5 no.2
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• pp.94-100
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• 1989

Friction and Wear behavior of continuous graphite fiber composites was studied for different fiber orientations against the sliding direction. The effect of fiber orientation on friction and wear of the composite and on the deformation of the counterface was investigated experimentally. Pin on disk type testing machine was built and employed to generate the friction and wear data. A graphite fiber composite plate was produced by the bleeder ply molding in an autoclave and machined into rectangular pin specimens with specific fiber orientations, i.e., normal, transverse, and longitudinal directions. Three different wear conditions were employed for two different periods of time, 24 and 48 hours. The wear track of the worn specimens and the metal counterface was examined with a scanning electron microscope (SEM) to observe the damaged fibers on the surface and wear film generation on the counterface. Wear mechanism of the composite during sliding wear is proposed based on the experimental results.