The honeycomb sandwich structure composite is a very efficient and complex structure widely used in the aircraft industry. Honeycomb-cored sandwich panels increase part stiffness at a lower weight than monolithic composite materials. This chapter describes the analysis of the intermingling of the film adhesive/prepreg resin system. It discusses the causes and effects of honeycomb core movement, which results in core crush. The chapter also explains the formation of a void in honeycomb composites and the failure mechanisms in honeycomb sandwich structure composites.

This chapter discusses the advantages and disadvantages of sandwich and integral cocured structures, and the methods by which they are made. It begins by explaining where and how sandwich construction is used and why it is so efficient. It then describes the design and fabrication of honeycomb panels and foam cores along with their respective applications and unique attributes. The chapter also discusses the cocuring process and its use in fabricating unitized structures.

The most common methods for preparing polymeric composites for microscopic analysis can be used for most fiber-reinforced composite materials. There are, however, a few composite materials that require special preparation techniques. This chapter discusses the processes involved in the preparation of titanium honeycomb composites, boron fiber composites, titanium/polymeric composite hybrids, and uncured prepreg materials.

This chapter discusses the use of nondestructive inspection methods, including visual, ultrasonic, radiographic, and thermographic techniques, and the types of flaws and damages they can reveal in composite parts and assemblies. It describes the basic principles behind each method along with best practices and procedures.

This chapter discusses design and certification considerations, including materials and process selection, the building block approach to certification, design allowables, and design guidelines. It also includes information on damage tolerance and environmental sensitivity.

This chapter discusses the primary methods used to repair composites, including fill repairs, injection repairs, bolted repairs, and bonded repairs. It also discusses issues associated with field repairs.

This chapter discusses composite testing procedures, including tension, compression, shear, flexure, and fracture toughness testing as well as adhesive shear, peel, and honeycomb flatwise tension testing. It also discusses specimen preparation, environmental conditioning, and data analysis.

Polymer-matrix composites are among the lightest structural materials in use today. They are also highly resistant to corrosion and fatigue and their load-carrying capabilities, such as strength and stiffness, can be tailored for specific applications. This chapter discusses the primary advantages and disadvantages of polymer-matrix composites, how they are produced, and how they perform in different applications. It describes the construction of laminates, the fibers and resins used, and the methods by which they are combined. It explains how strength, modulus, toughness, and high-temperature and corrosion behaviors are determined by the orientation, shape, and spacing of fibers, the number of plies, resin properties, and consolidation and forming methods. The chapter also covers secondary fabrication processes, such as thermoforming, machining, and joining, as well as production equipment and product forms, and include guidelines for optimizing tradeoffs when selecting fibers, resins, and production techniques.

This chapter reviews materials issues encountered in joining, including challenges involved in welding of dissimilar metal combinations; joining of plastics by mechanical fastening, solvent and adhesive bonding, and welding; joining of thermoset and thermoplastic composite materials by mechanical fastening, adhesive bonding, and, for thermoplastic composites, welding; the making of glass-to-metal seals; and joining of oxide and nonoxide ceramics to themselves and to metals by solid-state processes and by brazing. The classification, types, applications, and the mechanism of each of these methods are covered. The factors influencing joint integrity and the main considerations in welding dissimilar metal combinations are also discussed.

This chapter explains how to prepare metallographic samples for light microscopy and how to anticipate and avoid related problems. It describes standard practices and procedures for sectioning, mounting, grinding, and polishing and identifies common defects along with their causes and cures. It also provides recommendations for handling specific materials and addresses safety concerns.

Casting is the most economical processing route for producing titanium parts, and unlike most metals, the properties of cast titanium are on par with those of wrought. This chapter covers titanium melting and casting practices -- including vacuum arc remelting, consumable electrode arc melting, electron beam hearth melting, rammed graphite mold casting, sand casting, investment casting, hot isostatic pressing, weld repair, and heat treatment -- along with related equipment, process challenges, and achievable properties and microstructures. It also explains how titanium parts are produced from powders and how the different methods compare with each other and with conventional production techniques. The methods covered include powder injection molding, spray forming, additive manufacturing, blended elemental processing, and rapid solidification.