Sandwich-structured composite

About: Sandwich-structured composite is a research topic. Over the lifetime, 5853 publications have been published within this topic receiving 101126 citations.

On the characterisation of syntactic foam core sandwich composites for compressive properties

Abstract: Sandwich structures, especially those with honeycomb and grid structures as the core material, are very commonly employed in aircraft structures. There is an increasing use of closed-pore rigid syntactic foams as core materials in sandwich constructions because they possess a number of favourable properties. The syntactic foams, owing to their structure and formation, behave differently under compression compared to other traditionally used core materials. In the present study, therefore, syntactic foam core sandwich constructions are evaluated for their behaviour under compression in both edgewise and flatwise orientations. Further, the work characterises the relative performance of two sets of sandwich materials, one containing glass-epoxy and the other, glass/carbon hybrid-epoxy skins. As non-standard geometry test specimens were involved, only a comparative evaluation was contemplated in this approach. The experiments indicate that the nature of the reinforcement fabric in the skin has a bearing on the test results in edgewise orientation. Thus, the tendency towards initiation of vertical crack in the central plane of the core material, which is a typical fracture event in this kind of material, was found to occur after a delay for the specimens containing the glass fabric in the skin. Attempts are made to establish the correlation between observations made on the test specimen visually during the course of testing and the post-compression microscopic examinations of the fracture features.

Cellular Solids: The mechanics of honeycombs

Abstract: Introduction and synopsis The honeycomb of the bee, with its regular array of prismatic hexagonal cells, epitomizes a cellular solid in two dimensions. Here we use the word ‘honeycomb’ in a broader sense to describe any array of identical prismatic cells which nest together to fill a plane. The cells are usually hexagonal in section, as they are in the bee's honeycomb, but they can also be triangular, or square, or rhombic. Examples were shown in Fig. 2.3. Man-made polymer, metal and ceramic honeycombs are now available as standard products. They are used in a variety of applications: polymer and metal ones for the cores of sandwich panels in everything from cheap doors to advanced aerospace components; metal ones for energy-absorbing applications (the feet of the Apollo 11 landing module used crushable aluminium honeycombs as shock absorbers); and ceramic ones for high-temperature processing (as catalyst carriers and heat exchangers, for example). And many natural materials – wood is one – can be idealized and analysed as honeycombs (as we do in Chapter 10). If such materials are to be used in load-bearing structures an understanding of their mechanics is important. There is a second good reason for studying honeycombs: it is that the results shed light on the mechanics of the much more complex three-dimensional foams. Analysing foams is a difficult business: the cell walls form an intricate three-dimensional network which distorts during deformation in ways which are hard to identify.

Creep of Sandwich Beams with Polymer Foam Cores

Abstract: Polymer foam‐core sandwich panels are increasingly being considered for load‐bearing components in buildings. In addition to offering a high stiffness per unit weight, such panels give excellent thermal insulation and may be easily mass‐produced. But polymers creep at room temperature, limiting their use in structural applications. In this paper we model the creep of sandwich beams with linear viscoelastic polymer foam cores. A previous study indicated that the creep of a polymer foam can be described knowing the creep response of the solid from which it is made and the relative density of the foam. In this study, we combine the model for foam creep with the standard analysis of deflection of a sandwich beam to develop an expression for the creep of a sandwich beam with a polymer foam core. The results are compared with data from a series of tests on sandwich beams with aluminum faces and rigid polyurethane foam cores. The model gives a good description of their behavior at loading times up to 1,200 hours...