• Journal of the Korean Society for Railway
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• v.8 no.5
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• pp.411-418
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• 2005

This paper expounds the development of a user-friendly expert system for the optimal stacking sequence design of composite laminates subjected to the various rules constraints. The expert system was realized in the graphic-based design environment. Therefore, users can access and use the system easily. The optimal stacking sequence is obtained by means of integration of a genetic algorithm, finite element analysis. These systems were integrated with the rules of design heuristics under an expert system shell. The optimal stacking sequence combination for the application of interest is drawn from the discrete ply angles and design rules stored in the knowledge base of the expert system. For the integration and management of softwares, a graphic-based design environment that provides multi-tasking and graphic user interface capability is built.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.132-137
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• 2007

This paper explains compressive behaviors of sandwich composite laminates with adhesively bonded patches. The sandwich composite laminate is used for a train carbody structure and is of an aluminum honeycomb core and CF1263 woven fabric carbon/epoxy faces. The sandwich composite laminates were damaged by low velocity impact. The damaged sandwich composite laminate was repaired using scarf repair method. Then, the strength restoration of it was assessed by compressive test. From the test, it could be known that the compressive strength was restored up to 91% of undamaged one.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.37-41
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• 2003

In this study the mechanical behaviors of fiber metal laminates (FML) such as ARALL, GLARE and CARE which are recently developed as new structural materials and known to have excellent fatigue resistant characteristics while with relatively low densities compared to the conventional aluminum materials, are considered through the classical lamination theory. The mechanical properties such as elastic moduli, thermal expansion coefficients and hygro-thermally induced residual stresses in the fiber metal laminates are obtained and compared each other. Also load carrying mechanism between metal sheets and composite layers in the FML are considered.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.7 s.94
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• pp.1686-1699
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• 1993

In this paper, the thermal buckling of thick composite angle-ply laminates subject to uniform temperature distribution is studied. For the plates of 4-edges simply supported condition and those of 4-edges clamped condition, the critical buckling temperatue is derived, using tile finite element method based on the shear deformation theory. The effects of lamination angle, layer number, laminate thickness, plate aspect ratio and boundary constraints upon the critical buckling temperature are presented.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.7 s.178
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• pp.1810-1816
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• 2000

A hybrid composite APAL(Aramid Patched Aluminum alloy) , consisting of Al 2024-T3 aluminum alloy plate sandwiched between two aramid/epoxy laminates, was developed. The characteristics of tensile s trength were investigated and statistical properties of tensile strength were studied in terms of Weibull distribution probability with number of AFRP laminates. The tensile strength of APAL was inproportional to number of AFRP laminates and followed the two-parametic Weibull distribution.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.10
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• pp.2518-2534
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• 1993

Fracture behavior of carbon/epoxy laminates under pin loading is studied experimentally and analytically. Effects of ratios of specimen width to hole diameter and edge distance to hole diameter on bearing strength are investigated. Characteristic length of the laminates obtained using HK model has good agreement with the experimental data. The larger hole size induced, the lower bearing strength is measured under pin loading . The bearing strength and failure mode could be predicted using HK model and Zhangs analytical solution of stress distribution around a pin loaded hole. Chamis' prediction method of bearing strength is also considered to predict failure mode and bearing strength. A modification of Chamis' method is made using the factor of rupturc. The predicted bearing strength by the modified method is reasonably close to the experimental data.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.5
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• pp.1144-1149
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• 1994

Damage caused in CFRP laminates by low energy impact of steel ball are investigated ultrasonically. Two types of laminated specimens having different stacking sequence are used as a target material. The effects of pre-bending on the behaviors of impact damage are specifically discussed. The initiation and progagation behaviors of delamination were largely dependent upon the bending rigidity of each specimen. Specimen C having higher bending rigidity produced larger delamination damage than the Specimen D having relatively low bending rigidity, however it was little for the Specimen C. Application of pre-bending increased the apparent bending rigidity of target during impacting, it produced delamination at lower impact energy level compared to the case of no preload.

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.904-909
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• 2002

This paper contains the tension-tension and the tension-tension bearing fatigue characteristics of glass fabric/phenol composite laminates. The experimental results show that the bearing fatigue characteristics of the material is so excellent compared with the simple tension fatigue characteristics, that there are no needs of additional strengthening for mechanical joint parts when the parts are properly designed. The experimental data are also compared with the results of glass fabric/epoxy composite laminates.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.195-198
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• 2005

To investigate the strengthening efficiency of the Near Surface Mounted Reinforcement (NSMR) technique analytically, a structural model for the finite element method (FEM) able to simulate accurately the experimental results was determined. Applying the finite element model, parametric analysis was performed considering the groove depth and spacing of CFRP laminates. Analytical study on the groove depth revealed the existence of a critical depth beyond which the increase of the ultimate load becomes imperceptible. Analytical results regard to the spacing of the CFRP laminates showed that comparatively smooth fluctuations of the ultimate load were produced by the variation of the spacing and the presence of an optimal spacing range for which relatively better strengthening efficiency can be obtained. Particularly, a spacing preventing the interference between adjacent CFRP laminates and the influence of the concrete cover at the edges as well as allowing the CFRP laminatesto behave independently was derived.

• Journal of Ocean Engineering and Technology
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• v.16 no.2
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• pp.67-71
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• 2002

Damage process of CFRP laminates was characterized by Acoustic Emission (AE). The main objective of this study is to determine if the sources of AE in CERP laminates could be identified from the characteristics of the waveform signals recorded during monotonic tensile test. The time history and power spectrum of each individual wave signal recorded during test were examined and classified according to their special characteristics. The wave from and frequency of AE signal from a specimens is an aid to the determination of the extent of the different fracture mechanism such as matrix crack, debonding, fiber pull-out and fiber fracture as load is increased. Four distinct types of signals were observed regardless of specimen condition. The result showed that the AE method could be effectively used for analysis of fracture mechanism in CFRP laminates.