Honeycomb panel

The modern Russian MIA flaw detectors use pulse version of the method [1-3], which peirnits to produce very portable (0.7 - 1.5 kg) and simple instruments, convenient especially for in-service testing. The objects to be tested are multilayer structures of reinforced plastics, metals and other materials honeycomb panels, antenna fairings, propellers, helicopter rotors and so on. In mentioned instruments amplitude-frequency analog signal processing is used. 

K. G. T. Hollands, Natural Convection in Horizontal Thin-Walled Honeycomb Panels, J. Heat Transfer (95/4) 439-444,1973. 

K. G. T. Hollands, G. D. Raithby, R. B. Russell, and R. G. Wilkinson, Coupled Radiative and Conductive Heat Transfer Across Honeycomb Panels and Through Single Cells, Int. J. Heat Mass Transfer (27/11) 2119-2131,1984. 

Aerolam F Board. [Ciba-Geigy Plastics UK] Rigid, stable, lightweight honeycomb panels frar construction of tool framework. 

A molecular trap designed for a rocket nozzle flow of 22 g/sec of water vapor at a chamber temperature of 1280°K for a minimum of a 1-sec test run in the 10 torr range is shown in Figs. 7 and 8. The trap was required to fit within an existing 3-ft-diameter by 7-ft-long chamber. Aluminum honeycomb panels with 0.004-in.-thick webs were used with the tube length determined by a criterion of equal backreflection of molecules from within the tubes and from the 0.004-in-thick edges. 

Urea-formaldehyde adhesives were patented in 1920 but were first eommercialized around 1937. During World War II, stareh was modified with urea resins to make both waterproof adhesives and impregnants for paper, which led in the 1940s to phenolic-impregnated paper for the first durable honeyeomb eore for lightweight rigid honeycomb panels. 

Except for a very few very high-temperature brazed panels, all honeycomb panels are adhesive bonded. 

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. 

Metal-skinned honeycomb panels The type of repair will vary according to the damage. A dent in the skin, if the honeycomb is metal and it is not disbonded, may be repaired by treating the surface of the dent and some distance around, filling the dent with epoxy potting compound and bonding on an external plate to restore the buckling stiffness of the skin. 

A common problem with honeycomb panels is disbond between the skin and the honeycomb, especially at the edges. This often leads to corrosion. Usually, both skin and honeycomb have to be replaced over the whole disbonded area. This may be done using two-part epoxy paste adhesives curing between room temperature and 80 °C or using a film adhesive curing at 120 or 180 °C. If high temperature (i.e. 120 °C and above) repairs of any size are required, then tooUng may be necessary to maintain the shape of the part. 

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. 

Bolted metal plates are sometimes used for temporary repairs to composite-skinned honeycomb panels, but a result is the need for more extensive permanent repairs. 

Repair methods K B ARMSTRONG Methods for composites and honeycomb panels on large structures such as aircraft... 

Figure 2.20 Pizza Oven" Shape for Aerospace Honeycomb Panels...

The prime reason for accepting the penalties of a lengthened cycle time and the energy cost of heating solvent vapor beyond its normal boiling point is to be able to remove all liquid from parts with complicated stmctures. Two examples are honeycomb panels (with membranes or the ability to cup liquid solvents) used as structural materials for aerospace applications (at lower left), and porous materials which will be used to fabricate implants for humans. 

A two component, low viscosity PUR laminating adhesive system for panel construction, for application by roller and offering a high peel strength. Is also a proven repair system for honeycomb panels. 

Because of their newness, complete panels for A-300 solar cells are not yet available. Moreover, traditional panel construction with its steel backing is not viable for the robot. Thus, we will construct the solar panels in house, using quarter-inch honeycomb sandwich panels (Nomex core with fiberglass facing). The cell will be encapsulated in silicone. Similar honeycomb composite will be used to make the chassis box (Figure 8). The constraction and joinery of honeycomb panels are mature technologies in the aerospace field, and these materials supply area densities of 1.4 kg/m for solar panels and 2.5 kg/m for chassis walls. 

Typical Use Metals, ceramics, glass, wood, most plastics. Typical Use Fastener, potting and edge members for honeycomb panels. ... 

Typical Use Lamination of dissimilar materials. Honeycomb panels and sporting goods. 

Typical Use Fabrication of honeycomb panels with composite or metal skins. Surfacing composites before painting. Plastics. 

Typical Use Aerospace - Composites. Core splicing and edge sealing honeycomb panels. 

Thickness of the adhesive is varied to suit the specific application. For example, when the substrates to be bonded are smooth and uniform in thickness a light weight adhesive of about 5 mils in thickness is usually selected. For assemblies having large or variable gaps, adhesives up to 15 mils or higher in thickness are utilized. Examination of the honeycomb panel pictured in Fig. 1 makes it obvious that adhesive thickness is a critical factor that must be considered in the design of sandwich structure. The size of the adhesive fillets and thickness of the face bond adhesive determine the... 

Syntactic foams are generally supplied in paste form as either one-part heat cure or two-part room temperature cure systems. These systems usually contain hollow glass microspheres, and most commonly have densities in the 40 lb per cubic foot range. The major use of these paste foams (also known as potting compounds) is to provide local reinforcement of honeycomb panels where mechanical fasteners such as threaded bolts are to be inserted in order attach the bonded panel to another part... 

The over-all thermal conductivities of several honeycomb panels with various filler materials were determined experimentally and are shown in Fig. 2. The experimental curve for corkboard is repeated here for comparison purposes. A considerable range in thermal conductivity is seen, depending on which filler material is used in the honeycomb cells. At-200°F mean temperature, the overall fe-factors vary from 0.32 for rated density Min-K 501, to 0.99 for potassium titanate and epoxy mastic, while air-filled honeycomb yields a value of 0.46. The over-all conductivity values for honeycomb panels are higher than would be expected for the filler materials alone because of the heat conduction through the phenolic-laminate walls of the honeycomb cells. Taking this into account, the -factors agree with limited published data on the various filler materials (except for potassium titanate) within 20. Based on i -factors, the two Min-K and the... 

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