Papers by Keyword: Sandwich Composite

Abstract: Rubber wood has multiple functions especially in the furniture industry and other wood products such as plywood whereas the sawdust is further processed to become medium density fiberboard or wood plastic composites. These composites are useful yet are unable to become the structural components where mechanical performance is critical. An investigation was carried out to find out the mechanical properties of rubber wood honeycomb core in the fiber reinforced composites with glass fiber as its facesheet and epoxy as its matrix. Cell diameter fabricated at 7 mm with increasing cell wall thicknesses ranging from 1 mm to 3 mm respectively. In the flatwise tensile test, the results showed that the interfacial bonding strength increased by 21.6% with increasing wall thickness. As higher density increased and minimum strength improvement, the specific strength will be reduced. Meanwhile, wall thickness of 3 mm is only 1% away from the sandwich composite with solid rubber wood which has the most similar bonding strength as in climbing drum peel test with lower density.

Abstract: This study aims to investigate numerically the damage area of a sandwich composite structure. In this work, the optimal sandwich core modeling method was proposed. This study applied two modeling methods to compare their analysis results for the structural analysis of the sandwich composite structure. Firstly, the modeling of sandwich core structure was performed with laminate modeling method. Secondly, the modeling of core structure was performed with core solid modeling method. The laminate modeling method was compared with the core solid modeling method. For the modeling, a carbon/epoxy composite structure was applied to the face sheet. And a nomex honeycomb core was applied to the core. Finally, comparing the result of modeling as actual shape with the one of virtually applying the thickness and modeling, it was examined that the former had three times more stress than the latter.

Abstract: Several thermal insulation systems were developed for improvement of thermal performance of buildings. Exterior thermal insulation systems represent usually natural solution of the problem of low thermal resistance of building envelopes. However, in some cases, there is necessary to realize interior thermal insulation systems, what brings number of possible problems. Their common disadvantage is a limitation of interior space due to the thickness of thermal insulation layer and a possible condensation of water vapor which permeates the thermal insulation system. On this account, new sandwich composite with silica aerogel originally designed for application in interior thermal insulation systems is studied in the paper. Thermal properties are measured by two transient methods using devices ISOMET 2114 and RTB. The water vapor transport parameters are determined on the basis of dry cup and wet cup methods. The obtained data gives information on thermal and water vapor transport properties of the particular layers of sandwich composite and predetermines its behavior at real climatic exposure of building.

Abstract: This article presents underwater acoustics evaluation of glass fiber – polyurethane sandwich composite which is useful for ship materials. The composite consists of two main functional laminations namely structural and acoustical lamination. The structural lamination is constructed from polyester and polyethylene fibers while the polyurethane is potential for acoustical lamination. The fabrication involves vacuum bagging and conventional hydraulic methods. The materials will be treated in both with and without immersion in sea water. The immersion process takes time about 72 hours. The properties of acoustics for each materials generally have high insertion loss (maximum found 25 dB), but some of them can reach low insertion loss (below 5 dB). The optimization of combination between structural and acoustic materials is promising to be investigated in near future to achieve the optimum properties of materials in terms of sound transparency.

Abstract: Composite materials are finding new applications in many situations and are better than the conventional materials because of their excellent properties. In the present investigation, aluminium sandwich composite laminates are fabricated and their tensile property is evaluated. The structure of the composites and their fractured surface are studied by using Scanning Electron Microscope. The analysis of the experimental results indicated that the incorporation of aluminium stack as sandwich improves the properties and can be used as a structural material for construction.

Abstract: This paper outlines a finite element procedure for predicting the mechanical behaviour under bending of sandwich panels consisting of aluminium skins and aluminium honeycomb core. To achieve a rapid and accurate stress analysis, the sandwich panels have been modelled using shell elements for the skins and the core. Sandwich panels were modelled by a three-dimensional finite element model implemented in Abaqus/Standard. By this model the influence of the components on the behaviour of the sandwich panel under bending load was evaluated. Numerical characterization of the sandwich structure, is confronted to both experimental and homogenization technique results.

Abstract: Polyurethane (PU)/montmorillonite (MMT) composite foam were synthesized with reaction of diisocyanate with polyester polyol by a batch process. In this research, water was used as the blowing agent with TEGOSTAB B8407 and TEGOAMIN PMDETA as the surfactant and catalyst, respectively. Clay was used as filler for composite PU foam with the percentages varied from 0 wt% to 5 wt%. Polyurethane foam (Al-PU) sandwich composite was prepared using hand-lay up method where Al sheet was stacked onto PU foam using adhesive. The samples were characterized using flexural test analysis. Observations showed that PU foam has better failure deformation with flexural extension increased up to 9.44 mm. However, flexural stress and optimum load for sandwich composite are up to 3.63MPa and 410.78N respectively. Furthermore, Al sheet act as ductile skin to PU foam and prevent samples from rupture rapidly or avoiding the existence of brittle fracture. Modeling of composite using finite element software shows the ductile-like failure behavior in sandwich composite Al-PU foam even though the core itself is a rigid brittle foam.

Abstract: This paper investigates the influence of nanoclay content on sandwich composites under flexural and impact loading. Four different combinations of sandwich samples were made of fiberglass/nano-modified polyester as face sheets and polystyrene foam as core materials. The tested samples showed that the flexural and impact properties are greatly increased, over the range of nanoclay loading.

Abstract: The present study investigates numerically the compressive residual strength of indented sandwich composite panel. The composite is made of carbon fiber reinforced plastic (CFRP) face sheets and aluminum honeycomb core. The sandwich is loaded under quasi-static condition and along out-of-plane direction. A commercial finite element analysis software ABAQUS is used. The results show that the indented composite retains significant amount of strength after indentation. And, the post-indentation strength of the composite is about 65% its pre-indentation strength under compression.

Abstract: A innovative structure of sandwich composite rectangular plate with dimensions of 350 ×83.5×9.5mm was designed, it was made of unidirectional prepreg of carbon fibre and woven fabric prepreg of carbon fiber as face materials and paulownia as core material by hand lay-up performing and press molding technology for investigating the dynamic performance such as natural frequency and modal shapes. Based on testing the in-plane and out-plane mechanical properties of composite samples reinforced by unidirectional carbon fibre and carbon fiber woven fabric, a ANSYS FEA dynamic modeling was developed. According to the impulse response modal test method, a modal test system was established. The natural frequency test results showed that the minimum natural frequency of sandwich composite rectangular plate is about 616.45Hz which is higher about 27.5% than that of aluminum rectangular plate reinforced by carbon. The modal experiment indicated that the 1st modal shape, 2nd modal shape, 3rd modal shape and 4th modal shape of the sandwich composite rectangular plate were torsional vibration, flexural vibration shape, torsional flexural vibration and double-flexural vibration separately. It was found the calculating precision of FEA dynamic predication was very high, the dynamic predicating results by FEA could provide fundamental data to the optimal design high speed reciprocating sandwich composite rectangular parts.