Honeycombs aluminium

The RenTooling System uses an aluminium honeycomb and an epoxy paste to produce lightweight and stable tools. 

Figure 4.5 Layered structures with high bending stiffness, (a) Glass-fibre-reinforced skins on an aluminium honeycomb core (b) structural foam injection moulding with maximum density at the skins.

One of the first applications for the adhesive grade of PES is as a structural adhesive to upgrade the temperature performance of epoxy resins (17). Mixtures of PES with epoxy resin are used to stick the aluminium outer skin on to aluminium honeycomb and such structures are designed for a 10,000 hr lifetime at 300°F whioh is typical of idle performance requirements of some supersonic aircraft. This adhesive grade can also be used as a matrix for making carbon fibre composites which show hi ... 

The possibilities for making bonded structural sandwich elements in a variety of materials are very real. However, whilst there exist structural examples such as aluminium honeycomb panels (used in aircraft and transport applications) and metal skinned foam sandwich panels (used as the monocoque chassis in refrigerated transport applications), these composite constructions are normally utilised in non- or semi-structural ways. Typical skin materials are steel, aluminium, GRP and plywood, and common core materials are rigid foam polystyrene, polyurethane, polyisocyanurate, PVC, and honeycombed aluminium. In some instances the foam core is injected between the skins and adheres to them in others, adhesives are used to bond the separate components together. The nature of the manufaeturing process depends on the type of structure to be made, and the degree of investment in produetion maehinery. Both flat and eomplex eurved forms ean be made by a hand lay-up process as well as in an automated way. 

P(l) If aluminium honeycomb is used with electrically conducting composites (e.g. carbon fibre composites), construction shall ensure that the honeycomb is electrically insulated from the core by using a glass fibre interlayer to prevent potential internal galvanic corrosion problems occurring in wet environments. 

Similarly, with aluminium honeycomb structures, failure may occur at the skin or the surface of the honeycomb itself, especially if the respective surface preparation is poor (see Pre-treatment of aiuminium). Untreated aluminium alloy honeycomb can result in disbonding in service. The use of anodized aluminium alloy honeycomb is strongly recommended. 

Composite-skinned honeycomb panels These may use Nomex nylon paper honeycomb core, aluminium honeycomb or sometimes PVC (polyurethane or acrylic foam core). Dents are not acceptable in composite skins as they indicate fibre damage. Nomex core may split under a dent, so any such damage needs to be cut out and repaired. Nomex honeycomb can absorb considerable amounts of moisture. Wet honeycomb should be thoroughly dried or replaced. Moisture meters are available for use with Fibreglass, Kevlar or Nomex, but these meters will not work with carbon fibre because it is electrically conductive. Instruments that can indicate when carbon-fibre composites are dry enough to repair are few in number and very expensive. 

Aluminium honeycomb, in contrast to polymeric honeycombs, undergo permanent deformation under load plastics honeycombs recover ( plastic memory ). 

While the experimental results reported above were all collected at the laboratory scale, one proof-of-concept at an industrial scale has been recently reported in the open literature, involving a campaign of o-xylene oxidation runs in a tubular pilot reactor loaded with washcoated conductive (aluminium) honeycomb catalysts and operated under representative conditions for the industrial production of phthalic anhydride (PA). 

Typical Use Aluminium honeycombs. Typical Use Construction - bonding glass fibre reinforced plastics ... 

Typical Use Fabrication of aluminium honeycomb (node bonding). ... 

Unless there are obvious signs of contamination, aluminium honeycomb does not require pretreatment prior to bonding. 

If the adhesive used to form the integrally bonded sandwich panel is of such a chemistry that volatile matter is evolved during cure, then the potential pressure built up inside the individual honeycomb cells can be alleviated by using perforated honeycomb core this is particularly relevant to aluminium honeycombs. During processing, prior to applying the node bond adhesive stripes, the aluminium foil is passed over a perforating roll, which punches small holes in the foil. 

A second example is the fan track liner (above the fan blades below position L in Fig. 76 it can also be seen in the same relative position in Fig. 77). This assembly is a combination of aluminium honeycomb, Nomex honeycomb and a GRP laminate. The aluminium honeycomb is supplied pre-coated with a corrosion resistant epoxy primer ( Blue Dip ) and this is bonded directly to the engine casing using a paste or a film adhesive. A GRP septum layer is then bonded on as a top skin using the same adhesive. Finally, a small-cell Nomex honeycomb. 

RB-211 The hoop plates within the cascade reverser are Class I bonded sandwich structures where Redux 119 primed aluminium substrates are bonded to aluminium honeycomb, using Redux 319 film adhesive... 

CFM 56 Here both aluminium and carbon reinforced composite sandwich panel constructions are used. An aluminium bondment forms the inner structure of the acoustic panel. Perforated, Redux 119 primed skins are bonded to aluminium honeycomb, Redux 319 film adhesive having first been reticulated onto the core. The outer structure is a conventional bondment of a carbon reinforced composite skin bonded to the core. 

Embraer 145 The air intakes comprise conventionally constructed acoustic sandwich panels where pretreated and primed perforated aluminium skins are bonded to aluminium honeycomb, Redux 319 film adhesive having first been reticulated onto the core. 

Spoilers and Ailerons Typical bonded aluminium skinned aluminium honeycomb sandwich structures are produced using film adhesives such as FM-94 to bond the skins to the core and foaming film adhesives for core splicing the A.380 tends to use Nomex rather than aluminium honeycomb in these applications. More information on the design of control surfaces is given under the section on Boeing aircraft (Fig. 92). 

These problems led to significant research and development programmes being initiated in the UK and in the United States. Many new designs were offered to solve the problem. These included glass fibre reinforced skins to replace the aluminium and epoxy paste adhesives to replace the phenolics and PVC foams and aluminium honeycomb to replace the balsa wood. The Lockheed Corporation developed their own floors where epoxy paste adhesives were used to bond fibre-reinforced epoxy skins to the balsa wood core phenolic matrices were used for skins in known wet areas. 

It soon became clear that the use of aluminium honeycomb gave the compression strengths and the fatigue resistance which were required. Early development work and trials concentrated on the use of carbon fibre reinforced skins with Nomex honeycomb the combination of aluminium and carbon was not liked because of potential galvanic corrosion problems. 

Of all the current civil engines. Rolls Royce s Trent 7(X) does have high temperature requirements. The IFS of the thrust reversers has to operate for considerable periods of time at elevated temperatures (> 140-150°C). The component manufacturers, Hurel-Hispano, believe that this is asking too much of an epoxy adhesive and hence a Cytec-Fiberite BMI film adhesive (FM-2550) is used to bond this structure. Here the BMI adhesive is reticulated onto phosphoric acid anodised aluminium honeycomb. The core is then bonded directly onto pre-cured carbon-reinforced BMI laminates to form a sandwich structure, one of the skins being perforated to produce an acoustic panel , which helps reduce engine noise. 

The main structural component of the SR.N4 (British Hovercraft Corporation) according to Powis (1973) is a large sandwich panel 40 m long, 23 m wide and about 1 m thick. The top and bottom skins of this sandwich panel are made of 2 5 mx 1 25 mx 37 mm sandwich panels which are bolted to an egg-box structure made from aluminium shear web with bonded stiffeners. The skin panels are of 6 4 mm and 3 2 mm cell aluminium honeycomb made from foil 0-05-0-076 mm thick. The higher density core is used in the more highly stressed areas. The superstructure of the craft is composed of two vertical beams running fore and aft, which are fabricated from this aluminium sheet with bonded stiffeners. The roof is one unsupported span between... 

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