• Proceedings of the KSR Conference
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• 2005.05a
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• pp.251-256
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• 2005

This study was performed the heat transportation ratio of three types of the following sandwich panel by KS F 2278(2003) ; Type ${\sharp}1$ : Carbon/epoxy Aluminum Honeycomb and Balsa Core Sandwich Panel(Thickness : 37mm), Type ${\sharp}2$ : Carbon/epoxy Aluminum Honeycomb Core Sandwich Panel(Thickness : 57mm), and Type ${\sharp}3$ : Carbon/epoxy Aluminum Honeycomb Core Sandwich Panel(Thickness : 37mm). Also was performed the heat transportation of next three types of the following sandwich panel by KS F2277(2002) ; Type ${\sharp}4$ and ${\sharp}5$ : 27mm, and 35mm thick-Aluminum Honeycomb Sandwich Panels, and Type ${\sharp}6$ : 27mm thick-Foaming Aluminum Sandwich Panel. It is the larger area between the skin and core, the heat transportation ratio is the higher, and when it is composed of the hybrid composite structure, good insulation property was shown.

• Steel and Composite Structures
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• v.45 no.3
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• pp.467-482
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• 2022

One of the major failure modes in composite sandwich structures is the separation between skins and core. In this study, the effect of employing foam filled composite corrugated core on the skin/core debonding (resistance to separation between skin and core) is investigated both experimentally and numerically. To this aim, triangular corrugated core specimens are manufactured and compared with reference specimens only made of PVC foam core in terms of skin/core debonding under bending loading. The corrugated composite laminates are fabricated using the hand layup method. Also, the Vacuumed Infusion Process (VIP) is employed to join the skins to the core with greater quality. Utilizing an End Notched Shear (ENS) fixture, three point bending tests are performed on the manufactured sandwich composite panels. The results reveal that the resistance to separation capacity and flexural stiffness of sandwich composite has been increased about 170% and 76%, respectively by using a triangular corrugated core. The Cohesive Zone Model (CZM) with appropriate cohesive law in ABAQUS finite element software is used to model the progressive face/core interfaces debonding the difference between experimental and numerical results in predicting the maximum born load before the skin/core separation is about 6 % in simple core specimens and 3% in triangular corrugated core specimens.

• International journal of steel structures
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• v.18 no.5
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• pp.1541-1559
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• 2018

This paper addresses the dynamic loading characteristics of the shock tube onto sandwich steel beams as an efficient and accurate alternative to time consuming and complicated fluid structure interaction using finite element modeling. The corrugated sandwich steel beam consists of top and bottom flat substrates of steel 1018 and corrugated cores of steel 1008. The corrugated core layers are arranged with non-uniform thicknesses thus making sandwich beam graded. This sandwich beam is analogous to a steel beam with web and flanges. Substrates correspond to flanges and cores to web. The stress-strain relations of steel 1018 at high strain rates are measured using the split-Hopkinson pressure. Both carbon steels are assumed to follow bilinear strain hardening and strain rate-dependence. The present finite element modeling procedure with an improved dynamic impulse loading assumption is validated with a set of shock tube experiments, and it provides excellent correlation based on Russell error estimation with the test results. Four corrugated graded steel core arrangements are taken into account for core design parameters in order to maximize mitigation of blast load effects onto the structure. In addition, numerical study of four corrugated steel core placed in a reverse order is done using the validated finite element model. The dynamic behavior of the reversed steel core arrangement is compared with the normal core arrangement for deflections, contact force between support and specimen and plastic energy absorption.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.740-743
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• 2001

Sandwich structure is widely used in various fields of industry due to its excellent strength and stiffness compared with weight. We studied the sandwich structure which has honeycomb core type. We are concerned about its buckling and bending stress with respect to its side length, thickness and the height ratio of its unit core. After obtaining the buckling critical load of unit core, we applied it to the sandwich structure to observe the bending behavior. When we compared the buckling with bending stress under buckling critical load, we observed that models of which length ratio of unit honeycomb core, A, is lower than 0.04 and the thickness of core, t, is thicker than 0.09 mm, is subjected to the ultimate stress by bending before buckling.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.444-447
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• 2008

A sandwich plate with a truss core is composed of two face sheets and a truss core between the face sheets. In this paper, a metallic sandwich plate with a pyramidal truss core is investigated numerically, for its deformation and energy absorption ability under dynamic loading. To find the effect of mechanical properties on crashworthiness in the sandwich plate with a pyramidal truss core, various pyramidal cores were simulated and investigated. It appears that relative density and shear modulus of a pyramidal truss core effect the change of energy absorption.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.10
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• pp.80-87
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• 2006

Metallic sandwich plate with a truss core has metallic inner structures which have low relative density between a pair of metal skin sheets or face sheets. In this work, low impact tests have been carried out to examine the behavior of sandwich plates with a pyramidal truss core. For the low velocity impact, the impact apparatus of drop weight type has been fabricated. From the results of the experiments, maximum energy absorption is found to happen when the upper sheet fails. The sandwich plate loses its absorption ability as soon as the inner structures have been crashed completely and optimal core thickness has existed to maximize energy absorption. Comparing the metallic sandwich plate with the monocoque plate, the absorbed energy has been improved up to 160 % and the deflection decreased by up to 76%. As a result, the metallic sandwich plate with a truss core is shown to have good material for impact resistance and energy absorption.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.29-33
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• 2000

The purpose of this paper is to determine the effect of the autoclave inner pressure rate, heat-up rate, tool round angle, Thickness of core, height of joggle on defects, and to minimize the defects of aircraft sandwich structure reinforced with honeycomb core occurred in autoclave processing. The results showed that the geometry of aircraft sandwich structure and tool such as tool round angle, Thickness of core, height of joggle, and the autoclave cure conditions such as inner pressure rate, heat up rate strongly affected the core movement, core wrinkle, bridge phenomenon of prepreg and depression of core that occurred in autoclave processing.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.25-26
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• 2023

The internal core material and external color of a sandwich panel have a significant impact on the performance of the sandwich panel. For use on roofs and walls, the internal core material and external color must be considered. Therefore, the surface and back side temperatures were measured for each exterior color and inner core material type. For the internal core materials, urethane foam and Expanded Poly Styrene(EPS), which are core materials mainly used in sandwich panels, were selected. As colors, black and ivory were selected according to brightness, and a total of five colors were selected: red, blue, and green, which are the three primary colors of light. As a result, there were differences in surface and temperature depending on the external color and type of internal core material. Regardless of the color, the temperature was measured lower for panels with urethane foam than for panels with an internal core of EPS. This is believed to have been influenced by the difference in thermal conductivity of urethane foam being 0.023W/(m·K) and that of EPS being 0.032W/(m·K). In addition, panels with a black exterior color were found to have higher surface and back temperatures than panels of other colors, and ivory-colored panels had lower back temperatures regardless of the core material. This is proportional to the brightness and light-absorbing characteristics.

• Smart Structures and Systems
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• v.8 no.5
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• pp.487-499
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• 2011

The parametric resonance problems of axisymmetric sandwich annular plate with an electrorheological (ER) fluid core and constraining layer are investigated. The annular plate is covered an electrorheological fluid core layer and a constraining layer to improve the stability of the system. The discrete layer annular finite element and the harmonic balance method are adopted to calculate the boundary of instability regions for the sandwich annular plate system. Besides, the rheological property of an electrorheological material, such as viscosity, plasticity, and elasticity can be changed when applying an electric field. When the electric field is applied on the sandwich structure, the damping of the sandwich system is more effective. Thus, variations of the instability regions for the sandwich annular plate with different applying electric fields, thickness of ER layer, and some designed parameters are presented and discussed in this study. The ER fluid core is found to have a significant effect on the location of the boundaries of the instability regions.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.130-135
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• 2007

The mechanical characteristics of three types of core with two-dimensional isotropic patterns-triangular, hexagonal and starcell-were studied in applications to sandwich structures. The Young's modulus and shear modulus were calculated for the three core types in the direction normal to the faces. The compressive buckling strength and shear buckling strength were calculated by modeling each cell wall of the core as a plate under compressive or shear load. To verify this model, tests were conducted on scaled specimens to measures the compressive buckling strength of each core. The bending flexibilities of the three cores were also studied. Compliances for the three cores were measured using biaxial flexural tests. The three isotropic core patterns exhibited distinct characteristics. In the direction normal to the faces, all three cores had the same stiffness. However, the starcell core exhibited high flexibility compared to the other cores, indicating potential for application to curved sandwich structures.