• Journal of the Korea Convergence Society
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• v.8 no.7
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• pp.231-236
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• 2017

In this study, the inhomogeneous material composed of CFRP(carbon fiber reinforced plastic) and structural metal of SM45C is used for the light material. The finite element analysis on the basis of compact tension test was carried out by using the composite material for sandwich type bonded with the unidirectional CFRP that differs in fiber stacking angle at both sides with the core of SM 45C. CT test is the representative method to confirm the fracture behaviour due to crack in material under the load. The effect on crack and hole must be investigated in order to apply inhomogeneous material to mechanical structure. As the result of this study, the fracture behaviour by CT test of the composite material for sandwich was studied by simulation analysis. The sandwich composite of unidirectional CFRP with the stacking angle of [0/60/-60/0] has the superior strength and the maximum equivalent stress of about 182GPa.Also, the esthetic sense can be shown as the designed factor of shape with composite material is grafted onto the convergence technique.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.56-60
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• 2004

2단 또는 3단형으로 설계되고 있는 KSLV-I 발사체의 단연결부는 직경의 변화에 따라 원뿔대(Truncated cone) 구조물이 필요하다. 원뿔대형 구조물이 발사체의 외피일 경우에는 일반적인 실린더형 동체와는 다르게 공력에 의한 버페팅(buffeting)과 공력가열 등이 추가적인 설계인자로 고려되어야 한다. 복합재료 샌드위치 구조물은 외피의 굽힘 강성이 크고, 일체성형으로 실린더형 혹은 원뿔대형 구좁물을 쉽게 제작할 수 있어 단연결부에 적용되고 있다. 또한 위성어댑터(Payload Adapter)등에도 사용되어 우주발사체에는 매우 일반적인 구조물이다. 복합재료 샌드위치 구조물의 제작과 정적시험을 통하여 구조 특성을 알아보았다. 일체형 샌드위치 구조물의 효율을 높이기 위해서는 프레임과의 체결부를 효율적으로 설계하여야 하며 하중의 종류에 따라서 면재의 적층각도가 중요함을 알 수 있었다.

• Journal of Korean Society of Steel Construction
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• v.10 no.1 s.34
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• pp.11-24
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• 1998

The composite sandwich plate is constructed by combining two laminated facings with high strength and a thick core of light weight material. The governing equations for the analysis of bending of simply supported sandwich plates with laminated facings are derived and analysed using the analytical method including the local shear deformations. The accuracy of the approach is ascertained by comparing solutions from the sandwich plate theory with composite facings to the laminate plate theory. Since the present analysis considers the bending stiffness of the core and also the transverse shear deformations of the laminated facings, it is expected that the analysis is capable to analyze the general anisotropic laminated plates with global shear deformations.

• Composites Research
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• v.19 no.2
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• pp.13-19
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• 2006

In this paper, parametric study was carried out to design sandwich structures for EDM machines controlling stacking sequence, stacking thickness of composites and rib configuration. Sandwich structures which are dealt with in this paper are composed of fibre reinforced composite for skin material and foam or resin concrete for core materials. The sandwich column has cruciform rib to enhance bending stiffness of the structure and the bed has several vertical ribs to resist the normal forces and vibration. The design parameters such as rib thickness and stacking sequence were controlled to enhance the system robustness. Finite element analysis was also carried out to verify the variation of static and dynamic stiffness of the structures according to the variation of the parameters. Vibration tests were performed to verify the natural frequencies and damping ratios of the manufactured composite structures. The appropriate shape and configuration conditions for micro-EDM machine structures are proposed.

• Composites Research
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• v.26 no.1
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• pp.36-41
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• 2013

In this study, low velocity impact analysis on composite sandwich structure was performed. Sandwich structure configuration is made of Carbon-Epoxy face sheets and foam cores. For validating study, the results of an experimental and a finite element method analysis were compared previously. From the finite element method analysis results of sandwich panel, it was confirmed that the results of analysis was reasonable. Impactor velocity to initiate damage was estimated, and in order to investigate the damage at the predicted velocity, impact analysis using finite element method was performed. According to the impact analysis results of sandwich panel, it was confirmed that the damage was generated at the estimated impact velocity. Finally, The comparison of the numerical results with those measured by the experiment showed good agreement.

• Journal of Korean Society of Steel Construction
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• v.12 no.6
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• pp.749-758
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• 2000

This study presents a governing equations of bending behavior of sandwich plates with thick metal, polymer composite facings. Based on zig-zag models for through thickness deformations, the transverse shear deformation of composite facings is included. All edges of plate are assumed to be simply supported. Results of the bending analysis under lateral loads are presented for the influence of various lay up sequences of antisymmetric angle-ply laminated facings. The accuracy of the approach is ascertained by comparing solutions from the sandwich plates theory with composite facings to the laminated plates theory. Since the present analysis considers the bending stiffness of the core and also the transverse shear deformations of the laminated facings, the proposed method showed higher than that calculated according to the general laminated plates theory. The information presented might be useful to design sandwich plates structure with metal, polymer matrix composite facings.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.224-227
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• 2001

Adaptive analysis of multilayered composite and sandwich plates is carried out. The adaptive analysis is based on a finite element error form, which measures the difference between the through-the-thickness distribution of finite element displacement and the actual displacement. The region where the error-measure exceeds the prescribed admitted error value, the finite element mesh locally refined in the thickness direction using the mesh superposition technique. Several numerical tests are conducted to validate the effectiveness of the current approach for adaptive analysis of laminated plates.

• Composites Research
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• v.21 no.5
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• pp.15-22
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• 2008

This paper describes the results of structural integrity and crashworthiness of Automatic Guideway Transit(AGT) vehicle made of sandwich composites. The applied sandwich composite of vehicle structure was composed of aluminum honeycomb core and WR580/NF4000 glass fabric/epoxy laminate composite facesheet. Material testing was conducted to determine the input parameters for the composite facesheet model, and the effective equivalent damage model fer the orthotropic honeycomb core material. The finite element analysis using ANSYS v11.0 was dont to evaluate structural integrity of AGT vehicle according to JIS E 7105 and ASCE 21-98. Crashworthiness analysis was carried out using explicit finite element code LS-DYNA3D with the lapse of time. The crash condition was frontal accident with speed of 10km/h at rigid wall. The results showed that the structural integrity and crashworthiness of AGT vehicle were proven under the specified loading and crash conditions. Also, the modified Chang-Chang failure criterion was recommended to evaluate the failure modes of composite structures after crashworthiness event.

• Composites Research
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• v.30 no.6
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• pp.384-392
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• 2017

Sandwich panels with three different joint configurations were tested to design a novel sandwich joint structure that can effectively support both the tensile and compressive loads. The sandwich core was mainly aluminum flex honeycomb but the PMI foam core was limitedly applied to the ramp area which is transition part from sandwich to solid laminate. The face of sandwich panel was made of carbon fiber composite. For configuration 1, the composite flange and the sandwich panel were cocured. For configurations 2 and 3, an aluminum flange was fastened to the solid laminate by HI-LOK pins and adhesive. The average compressive failure loads of configurations 1, 2, and 3 were 295, 226, and 291 kN, respectively, and the average tensile failure loads were 47.3 (delamination), 83.7 (bolt failure), and 291 (fixture damage) kN, respectively. Considering the compressive failure loads only, both the configurations 1 and 3 showed good performance. However, the configuration 1 showed delamination in the corner of the composite flange under tension at early stage of loading. Therefore, it was confirmed that the structure that can effectively support tension and compressive loads at the same time is the configuration 3 which used a mechanically fastened aluminum flange so that there is no risk of delamination at the corner.

• Composites Research
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• v.19 no.3
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• pp.23-28
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• 2006

Carbon nanotubes reinforced copper matrix laminated nanocomposites were developed and the mechanical properties were evaluated by using micro-tensile testing system. Sandwich-type laminated structure constituted with carbon nanotube layers as a reinforcement and electroplated copper matrix were fabricated by a new processing approach based on selective dip-coating of carbon nanotubes. The mechanical properties of nanocomposites were improved due to an enhanced load sharing capacity of carbon nanotubes homogeneously distributed within the in-plane direction, as well as a bridging effect of carbon nanotubes along the out-of-plane direction between the upper and lower matrices. The universality of the layering approach is applicable to a wide range of functional materials, and here we demonstrate its potential use in reinforcing composite materials.