Lightweight structural cores are used on aircrafts to reduce weight and increase payload and fight distance. This article discusses the classification of lightweight structural cores, namely, honeycomb, balsa, and foam. It reviews the four primary manufacturing methods used to produce honeycomb: adhesive bonding and expansion, corrugation and adhesive bonding, corrugation and braze welding, and extrusion. The article describes cell configuration and properties of honeycomb. It discusses the factors influencing specification of structural cores, including materials, size, density, mechanical properties, environmental compatibility, formability, durability, and thermal behavior. The article provides information on the benefits and concepts of a sandwich panel containing lightweight structural cores.

This article describes manufacturing procedures that produce aluminum foams and have since become industrially important and successful. It discusses the foaming of melts by blowing agents and foaming of melts by gas injection. The article focuses on aluminum foams based on the Foaminal technology, because those foams dominate the technical applications of aluminum foams. It also discusses the mechanical properties of metal foams, such as general compression behavior, elastic behavior, strain-rate sensitivity, tensile behavior, ductility, fatigue, and mechanical damping. The article concludes with information on the applications of highly porous metal structures.

Cellular or foam structures can be described by means of two broader cases: foams in which the pores are all connected to each other and with the environment (open-pore foams) and foams in which every single pore is completely enclosed by the matrix (closed-pore foams). This article describes the four process groups for the production of open- and closed-pore metal foams. It discusses the principles of the foaminal process with the description of various foaming agents, solidified metal foam, and geometries and derived structures of metal foams. The use of syntactic metal foam in various fields is included. The article reviews the mechanical properties of closed-pore metal foams, details the machining and joining procedures of the metal foams, and presents the applications of the metal foam.

Resin transfer molding (RTM) and structural reaction injection molding (SRIM) are two similar processes that are well suited to the manufacture of large, complex, and high-performance structures. This article discusses the similarities and differences of RTM and SRIM processes and the unique design considerations with respect to the physical properties, geometry, surface quality, process economics, equipment, and tooling of a component that should be considered in choosing RTM or SRIM over other competing processes for fabricating reinforced components.

Injection molding is a process of forcing or injecting a fluid plastic material into a closed mold. The process generally has the advantages of being more readily automated and of permitting finer part details. Injection-molding compounds are thermoplastic or thermosetting materials and their composites that are specifically formulated for the injection-molding process. This article discusses the injection molding process, which includes the two basic categories of thermoplastic and thermoset injection molding, and lists the common thermoplastic and thermoset molding compounds and applications. It also describes the operation of the different types of injection molding machines as well as mold design and process controls. The article also describes the selection of injection-moldable thermosets, and provides an overview of part performance, properties, blowing agents, and aesthetic concerns related to thermoplastic structural-foam injection molding.

Honeycomb is a product consisting of very thin sheets attached to form connecting cells. This article briefly explains the construction, core characteristics, properties, and testing methods of the honeycomb structures. It discusses the special processes carried out in customizing the shape of core to fit customer's specific needs. The article provides information on the basic concept of creating sandwich structures and its corresponding aspects like material selection, design guidelines, and structural efficiency.

This article focuses on the design process, materials, and manufacturing techniques for one-off and low-volume production sailing craft. These include racing yachts of typically 10-20 m length for short coastal events, 20-25 m ocean racers, 24 m America's Cup racing craft, multihull racers of 35 m or more, and large luxury cruising craft. The article discusses the tooling, laminating practice, curing, mold removal, and quality control, for manufacturing hulls, decks, masts, and appendages using composites.

This article discusses the historical background of composite construction in recreational equipment and sporting goods. It provides information on the applications of composites in baseball bats, tennis rackets, and golf clubs. The applications of composites in bicycling, winter sports, aquatic sports, track, field, and archery equipment are also discussed.

Adhesive-bonded joints are extensively used in aircraft components and assemblies where structural integrity is critical. This article addresses the problem of how to inspect bonded assemblies so that all discrepancies are identified. It describes several inspection techniques and presents drawbacks and limitations of these techniques. Generic flaw types and flaw-producing mechanisms are listed in a table. The article discusses metal-to-metal defects, adherend defects, honeycomb sandwich defects, repair defects, and in-service defects. It reviews the methods applicable to the inspection of bonded structures, including visual inspection, ultrasonic inspection, X-ray radiography, and neutron radiography. The evaluation and correlation of inspection results are also discussed. The article concludes with information on the effects of ultrasonic wave interference in the ultrasonic inspection of adhesive-bonded joints.

Manufacturing process selection is a critical step in plastic product design. The article provides an overview of the functional requirements that a part must fulfil before process selection is attempted. A brief discussion on the effects of individual thermoplastic and thermosetting processes on plastic parts and the material properties is presented. The article presents process effects on molecular orientation. It also illustrates the thinking that goes into the selection of processes for size, shape, and design factors. Finally, the article describes how various processes handle reinforcement.

Designing composites for structural performance initially involves meeting a set of desired performance specifications at a minimum cost. This article discusses the factors that are considered in designing the manufacturing of polymeric composites. It describes the various aspects of manufacturing, forming process, and post-processing and fabrication for designing the composites.

This article discusses the categories and subcategories of shape casting processes. These include single-use processes such as sand, plaster, ceramic, and graphite molding; essentially unpressurized multiuse processes, such as permanent mold; and high-pressure metal mold methods, such as die casting, squeeze casting, and semisolid processing. The article contains tables that compare some of the typical capabilities of shape casting processes.

This article discusses slurry molding that encompasses two distinct processes: plaster molding and ceramic molding. Plaster mold casting is a specialized casting process used to produce nonferrous castings that have greater dimensional accuracy, smoother surfaces, and more finely reproduced detail. The article describes three generally recognized plaster mold processes, namely, conventional plaster mold casting, the Antioch process, and the foamed plaster process. Ceramic molding techniques are based on processes that employ permanent patterns and fine-grained zircon and calcined, high-alumina mullite slurries for molding. The Shaw process and the proprietary Unicast processes are also discussed.

This article provides a general introduction on casting processes and design techniques. It discusses the process steps and methods of the main categories of shape casting methods, namely, expendable molds with permanent patterns, expendable molds with expendable patterns, and metal or permanent mold processes. The article lists the general guidelines of geometry in casting design. It describes the three separate contractions that are a result of cooling: liquid-liquid contraction, solid-solid contraction, and liquid-solid contraction. Factors influencing the solidification sequence of simple shapes, such as T-sections, X-sections, and L-sections, are discussed. The article also presents an overview of geometric factors that influence heat transfer and transport phenomena. It concludes with a description of the structure and properties of castings.

The goal of design is to improve the overall performance of the metal or ceramic matrix rather than to create a material with different response than the base matrix. This article focuses on the design for manufacturing polymeric composites. Specially developed methods including contact molding, compression-type molding, resin-injection molding, and pultrusion are described. The article also discusses the various factors to be considered in designing for composite manufacturing.

Resin transfer molding and structural reaction injection molding belong to a family, sometimes denoted as liquid composite molding. This article provides information on the characteristics and automotive and aerospace applications of liquid composite molding. It reviews techniques that use hard tooling and positive (superatmospheric) pressures to produce structures. The techniques include vacuum-assisted resin injection, vacuum infusion, resin-film infusion, and injection-compression molding. The article provides an overview of the materials that are commonly used together with some of processing characteristics that are important to processing speed and part quality. It concludes with a discussion on design guidelines for the liquid composite molding.

In the handling of molten aluminum, it is fairly common to use filters as a part of the melting unit and in the gating and/or riser system. This article describes the methods of in-furnace and in-mold filtration, with an emphasis on the filtration of molten aluminum. It discusses the factors that influence the formation of inclusions. The article describes the three basic methods of mechanically removing or separating inclusions from molten metal. The methods include sedimentation, flotation, and positive filtration. The article provides a discussion on the types of molten-metal filters, including bonded-particle filters, cartridge filters, and ceramic foam filters. It lists the factors that are important in achieving optimum performance of any in-furnace filtering application. The article concludes with information on filtered metal quality and the methods of evaluation.

This article discusses classification of foundry processes based on the molding medium, such as sand molds, ceramic molds, and metallic molds. Sand molds can be briefly classified into two types: bonded sand molds, and unbonded sand molds. Bonded sand molds include green sand molds, dry sand molds, resin-bonded sand molds, and sodium silicate bonded sand. The article describes the casting processes that use these molds, including the no-bake process, cold box process, hot box process, the CO2 process, lost foam casting process and vacuum molding process. The casting processes that use ceramic molds include investment casting, and plaster casting. Metallic molds are used in permanent mold casting, die casting, semisolid casting, and centrifugal casting.

It is recommended that repairs be made whenever damage consists of delamination cracks or broken fibers. This article provides an overview of the repair classification, characterization, and cycle of the composite ship structure. The methods outlined in this article, which covers gel coat repairs, patching, scarfing, and step repairs, have undergone extensive development and rigorous testing for use on composite ship structures. Resin infusion repair, which is a relatively new method for repairing marine composites, is also described.

This article illustrates the polymer matrices used for composite materials. It describes the use of prepeg materials in manufacturing high-performance composites. The article discusses the various infusion processes for the development of fiber-reinforced composites, namely, resin transfer molding, vacuum-assisted resin transfer molding, and resin film infusion. It explains the composite- and matrix-toughening methods for fiber-reinforced composites, such as dispersed-phase toughening and interlayer toughening. The article concludes with information on optical microscopy, which provides an insight into the micro- and macrostructure of fiber-reinforced composites.