STP201: Recent Developments in Sandwich Construction Including Heat-Resistant Materials

    Steele, Roger C.
    President and Regional Manager, Hexcel Products Inc., Oakland, Calif.

    Marshall, Andrew C.
    President and Regional Manager, Hexcel Products Inc., Oakland, Calif.

    Pages: 8    Published: Jan 1957


    Abstract

    In reviewing recent developments in sandwich construction, the most noteworthy areas deserving consideration and comment would appear to be: 1. The much wider acceptance of sandwich by the airframe industry, resulting in greatly increased usage, particularly in primary structures; 2. The current trend toward the use of the stronger 5052 aluminum cores in place of the 3003 alloy core materials formerly used in most aluminum core sandwich, and 3. The widespread activity in developing (and adapting) new materials and techniques to meet the problems imposed by high temperatures. The fundamental advantages of lowdensity core sandwich structures such as strength, light weight, rigidity, smooth exteriors, fewer parts, and simplified fabrication have been generally known for many years; the much wider application of sandwich in the present era is due primarily to an increasing knowledge concerning the design, fabrication, strength, and reliability of sandwich parts. With a few exceptions, the early sandwich applications in aircraft were in general limited to such parts as flooring, equipment shelves, fuel cell support panels, table tops, access doors, and bulkheads; more recently we observe a widespread trend toward the use of sandwich construction in such parts as rudders, elevators, stabilizers, ailerons, trailing edges, flaps, wing tips, rotor blades, dive breaks, and including the wings, themselves, on both manned and unmanned vehicles. In many of these parts the core runs through from one exterior surface to the other, the core being tapered or contoured to the shape of the part. The appropriate use of internal doublers and laminated facing sheets eliminates the need for the more costly tapered skins which might otherwise be required in applications such as wings. In thicker parts, such as in the wings of the B-57 and B-58 military aircraft, the upper and lower wing surfaces are composed of separate sandwich panels approximately 1/2 in. thick and employ cores of constant thickness. There is a definite trend toward the use of 5052 aluminum honeycomb in place of the 3003 alloy, not only in new designs but also in many existing parts. 5052 honeycomb is not new, having been made as laboratory samples many years ago; it has only recently become a production material. The 5052 material is some 20 to 25 per cent stronger for the same density and may therefore be used either to increase strength at the same weight or to reduce the weight without sacrificing strength. The comparative strength properties of these two aluminum materials can be observed in Fig. 1 where the 5052 honeycomb displays a marked superiority at all temperatures up to 400 F. The 5052 material is expected to replace the 3003 alloy as the standard material for general use in aircraft.


    Paper ID: STP46888S

    Committee/Subcommittee: D14.10

    DOI: 10.1520/STP46888S


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