This article describes the types of fabrics and preforms used in the manufacture of advanced composites and related selection, design, manufacturing, and performance considerations. The types of fabrics and preforms include unidirectional and two-directional fabrics; multidirectionally reinforced fabrics; hybrid fabrics; woven fabric prepregs; unidirectional and multidirectional tape prepregs; and the prepreg tow. The article discusses three major categories of tape manufacturing processes, namely, the hand lay-up, machine-cut patterns that are laid up by hand, and the automatic machine lay-up. It provides a description of the two classes of prepregs. These include those that are suitable for high-performance applications and suitable for lower-performance molding compounds.

This article schematically illustrates a fiber placement system and provides information on the applications of fiber placement. It discusses materials and design considerations for fiber placement. The article provides information on techniques that can be used to eliminate areas of missing tows.

Filament winding is a process for fabricating a composite structure in which continuous reinforcements, either previously impregnated with a matrix material or impregnated during winding, is placed over a rotating form or mandrel in a prescribed way to meet certain stress conditions. This article describes the advancements in filament winding and lists the advantages and disadvantages of filament winding. It discusses the effects of fiber tension in filament winding and the selection of fibers, resins, and materials for filament winding. The article emphasizes the three basic filament-winding patterns, such as helical, polar, and hoop. It presents information on the applications of filament winding, including rocket motors, natural gas vehicle (NGV) tanks, and sporting goods. The article presents recommendations for the basic design guidelines for filament-winding design/manufacturing process and concludes with a discussion on fabrication recommendations.

In-process inspection during composite material lay-up is essential if the structural, dimensional, and environmental performance designed into a part is to be consistently achieved. This article discusses the requirements to be met by the facilities and equipment to produce high-quality composites. It reviews the procedures that are allowed and prohibited in controlled-contamination areas of lay-up. The article emphasizes significant areas, such as material control and lay-up process, in which quality-control personnel can be effective in preventing production problems. It concludes with a discussion on automated tape laying and fiber placement, as well as the numerically aided lay-up process.

This article addresses the types, properties, forms, and applications of fibers that are available for use in fiber-reinforced polymeric matrix composites, including glass, graphite, carbon, aramid, boron, silicon carbide, ceramic, continuous oxide and discontinuous oxide fibers. It describes the functions, types, and chemical composition of fiber sizing agents. The article discusses the styles, properties, applications, and weaving methods of unidirectional, two-directional and multidirectionally reinforced fabrics. The article also reviews the use of prepreg resins in aerospace and lower performance applications.

Filament winding is a process that allows the precise lay-down of continuous reinforcement in predescribed patterns at a high rate of speed. This article discusses the filament winding process and includes a comparison to other compacting and curing processes. The article describes design factors, and techniques to produce aerodynamic surfaces, improve surface smoothness, and avoid slipping and bridging of filament. The article discusses tooling and the equipment used in the filament winding process, namely, mandrel design, winding machines, tensioners, and ovens.

This article describes the most significant tests to characterize the properties of constituent materials. It discusses the chemical, physical, and mechanical tests for determining the properties of reinforcement fibers and fabrics. The article provides information on some of the basic materials used for thermoset and thermoplastic resin matrices. It reviews the identification of the individual characteristics of thermoset and thermoplastic resin along with the test methods normally used for their determination. The article contains a table that lists properties and tests for uncured and cured thermoset-matrix resins and prepregs.

The prepreg hand lay-up process is a versatile, reliable, cost-effective, and high quality process for fabricating large or small components. This article discusses the technique characteristics and applications of the process. It describes the stages involved in the process of lay-up, namely, lay-up definition, ply-kit cutting, layup, debulking, and preparation for curing. The article concludes with a discussion on the component properties and design guidelines of the prepreg hand lay-up process.

This article describes the dispersed-phase toughening of thermoset matrices by the development of multiphase-structure thermosetting matrices using rubber and/or thermoplastic materials. It discusses two main methods for manufacturing prepregs, namely, single-pass impregnation and double-pass impregnation. The article illustrates reflected-light optical microscopy techniques to evaluate the morphology of thermoplastic materials for determining the material quality and correlating key microstructural features with material performance.

This article provides a summary of the concepts discussed in the articles under the Section “Constituent Materials” in ASM Handbook, Volume 21: Composites. The Section describes the major matrix resins and reinforcing fibers used in composite materials, as well as some of the intermediate material forms available for composite fabrication.

High-temperature-resistant polymers are used in aerospace, electronic, and other applications that demand outstanding elevated-temperature physical and mechanical properties. This article discusses the general characteristics of condensation-type polyimides and polymerization of monomer reactants (PMR) polyimides. It provides information on the applications of PMR-15 with illustrations.

This article focuses on the sample preparation methods for titanium honeycomb composites, boron fiber composites, and titanium/polymeric composite hybrids. These include mounting, sectioning, grinding, and polishing. The article also provides information on the sample preparation of unstaged and staged prepreg materials for optical analysis.

This article focuses on the process methods and matrix chemistries of ceramic-matrix composites. These methods include pressure-assisted densification, chemical vapor infiltration, melt infiltration, polymer infiltration and pyrolysis, and sol-gel processing. The article discusses the use of a ceramic, preceramic, or metal phase as a fluid or vapor phase reactant to form the matrix. Emphasis is placed on microstructural features that influence ultimate composite properties.

Voids in fiber-reinforced composite materials are areas that are absent of the composite components: matrix (resin) and fibers. Voids have many causes but generally can be categorized as voids due to volatiles or as voids that result from entrapped air. This article describes the analysis of various types of voids. It reviews techniques for analysis of voids at ply-drops, voids due to high fiber packing, and voids that occur in honeycomb core composites. The final section of the article discusses void documentation through the use of nondestructive inspection techniques and density/specific gravity measurement methods.

Rehabilitation is the process of repairing or modifying reinforced concrete structures to a desired useful condition. This article describes the operational steps for the structural assessment of reinforced concrete structures. It discusses the classification of composite materials reinforcing systems for strengthening reinforced concrete structures, such as shop-manufactured and field-manufactured structures. The article reviews the materials property requirements for designing reinforcing systems to strengthen the reinforced concrete structures. It discusses the fiber-reinforced polymer (FRP)-reinforced concrete behavior that depends on flexural, shear, or axial failures. Surface preparation procedures for rehabilitation techniques of reinforced concrete structures using bonded FRP materials are also discussed. The article provides information on the applications of rehabilitation of concrete structures. It explains data recording and acceptance criteria for rehabilitation of concrete structures with composite materials.

This article provides information on the thermoplastic resins used as matrix materials for continuous fiber reinforced composites. It focuses on the materials that are suitable for fabrication of structural laminates and used for aerospace applications. The article provides a discussion on the background, categories, characteristics, product forms, properties, cost benefits, and processing techniques of thermoplastic resins. Strategies that have been advanced to deal with impregnation difficulties are also discussed.

Cyanate ester resins are a family of high-temperature thermosetting resins that bridge the gap in thermal performance between engineering epoxy and high-temperature polyimides. This article discusses the chemistry, properties and characteristics of the cyanate ester resins. It describes the processing procedures for the cyanate ester resins and provides information on properties for selected applications, such as space applications, radomes, and printed circuit boards.

The earliest commercial use of carbon fibers is often attributed to Thomas Edison's carbonization of cotton and bamboo fibers for incandescent lamp filaments. This article describes the manufacture of PAN-based carbon fibers and pitch-based carbon fibers. It discusses the properties and characteristics of carbon fibers in terms of axial structure, transverse structure, and interfacial bonding. The article discusses the typical applications of carbon fibers, including aerospace and sporting goods. It concludes with a discussion on anticipated developments in carbon fibers.