Structural adhesive aerospace

Allbericci, P, Aerospace applications. In Kinlock, A.J. (Ed.), Durability of Structural Adhesives. Applied Science Publishers, London, 1983, Ch. 8. 

The aerospace field is a broad one and has a complex history. A comprehensive review of structural adhesive applications on currently flying aerospace vehicles alone could fill its own book. Hence this chapter will concentrate on the aerospace commercial transport industry and its use of adhesives in structural applications, both metallic and composite. Both primary structure, that is structure which carries primary flight loads and failure of which could result in loss of vehicle, and secondary structure will be considered. Structural adhesives use and practice in the military aircraft and launch vehicle/spacecraft fields as well as non-structural adhesives used on commercial aircraft will be touched on briefly as well. 

National Materials Advisory Board, National Research Council, Structural Adhesives with Emphasis on Aerospace Applications. Marcel Dekker, Inc., New York, 1976. 

Following this initial period of polyimide development, interest reached a steady-state and remained there until the late 1970s. During this time a major impetus to the polyimide area was provided by the aerospace industry. The need for composite matrix resins as well as structural adhesives with excellent oxidative and thermal stability appeared to be at least partially met by polyimide type resins. Ultimately, requirements of high flow and low void content in relatively thick parts directed these efforts into different directions. Another upswing occurred in the early 1980s with the potential application of... 

Epoxy adhesives have become the most recognizable structural adhesive type. They have found commercial success in demanding industries such as aerospace, automotive, building and construction, and electrical and electronic. Their ease of use has also encouraged their commercialization in the do-it-yourself markets, which has added to the exemplary reputation of epoxy adhesives. 

Aircraft and Aerospace. Adhesives have always played a significant role in the aircraft and aerospace industries primarily because they offer a low-weight, fatigue-resistant, and aerodynamically sound method of assembly. Adhesive bonding is also less labor- and costintensive when applied to large structures such as those commonly utilized in the aerospace industry. Structural adhesives account for the greatest market share of all the adhesives used in aerospace applications. 

In the aerospace market a distinction is made between primary and secondary structural applications. Joint failure in a primary structure will result in the loss of the aircraft, whereas failure in a secondary structure will result in only localized damage. Structural adhesives are used in both applications. Figure 1.4 illustrates the degree to which adhesive bonding is used in modem aircraft. 

Boeing Company, Seattle, WA also in Politi, R. E., Structural Adhesives in the Aerospace Industry, Handbook of Adhesives, 3d ed., I. Skiest (ed.), van Nostrand Reinhold Publishing, New York, 1990. 

Savia, Epoxy Resin Adhesives, and Politi, Structural Adhesives in the Aerospace Industry. ... 

Epoxy structural adhesives are used in an extraordinarily wide range of applications. They are available in essentially all of the forms discussed above, except for primer—liquid combinations or as room temperature curing liquids. The liighest technology7 application for epoxies is in aerospace structural... 

Phenolic resins are the oldest form of synthetic structural adhesives. Usage ranges from bonding automobile and other types of brake linings to aerospace applications. These adhesives have a reputation for providing the most durable structural bonds to aluminum. Because of volatiles, however, and the need for high pressures, the phenolic resins are used less as adhesives than the epoxy resins. 

Major polymer applications aerospace, electronics (mostly films and coatings), photosensitive materials for positive imaging, solar cells, hollow fiber membranes, composites. unclear power plants, space shuttle, microprocessor chip carriers, structural adhesives... 

Highly cross-linked epoxy resins combine high strength stiffness thermal, chemical, and environmental stability adhesion low weight processability excellent creep resistance and favorable economics. These resins are widely applied as coatings, casting resins, structural adhesives, and matrix resins of advanced composite materials. The broad spectrum of applications ranges from the automotive and aerospace industries to corrosion protection and microelectronics. 

In the aerospace industry, resinous polymers encompass a wide variety of hardware applications for aircraft, missiles, and space structures. In aircraft, resins are used as a matrix material for primary (flight-dependent) and secondary fiber-reinforced composite (FRC) structures, adhesives for the bonding of metal and composite hardware components, electronic circuit board materials, sealants, and radomes. Missile applications include equipment sections, motor cases, nose cones, cartjon-carbon composites for engine nozzles, adhesive bonding, and electronics. As the exploration of outer space intensifies, applications will become even more exotic. FRC will be used to construct telescopes, antennas, satellites, and eventually housing and other platform structures where special properties such as weight, stiffness, and dimensional stability are important. 

Although the consumption of these materials in aerospace is but a small fraction of the resinous polymers used in industry, the impact of the needs and applications is large. Virtually all modern day structural adhesives have aerospace origins. The need for elevated temperature performance resulted in polymers useful for such diverse applications as electrical insulation and brake linings. The search for coatings to resist rain errosion and UV light contributed heavily to the technology of the polyurethanes. 

Most current applications for reactive adhesives are as structural adhesives (16). They compete with high performance epoxies and urethanes and, in certain cases, with anaerobics and cyanoacrylates - in stringent aerospace, aircraft, electrical, electronic, marine, instrument and other uses (1,2,14). The reactive adhesives do not require the sophisticated fixturing usually needed... 

National Academy of Sciences (1974), Committee on Structural Adhesives for Aerospace Use, Final Report, U.S. Government Printing Office, July, 1974. 

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