Search Results for tough-matrix composites

As fiber-reinforced polymeric composites continue to be used in more damage-prone environments, it is necessary to understand the response of these materials when subjected to impact from foreign objects. This chapter provides an overview of the analysis methods for impact-damaged composites. It discusses the causes and effects of various failure mechanisms in composite materials. The failure mechanisms covered are brittle-matrix composite failure, tough-matrix composite failure, thermoplastic-matrix composite failure mechanisms, untoughened thermoset-matrix composite failure mechanisms, toughened thermoset-matrix composite failure mechanisms, particle interlayer-toughened composite failure mechanisms, and dispersed-phase, rubber-toughened thermoset-matrix composite failure mechanisms.

The second-generation composite materials were added to increase the strain to failure of the primary phase and/or create a dispersed second phase, thereby enhancing the fracture toughness of the thermosetting matrix. These matrices offered novel design capabilities for composites in a variety of aircraft applications. To improve the damage tolerance of composite materials even further, an engineering approach to toughening was used to modify the highly stressed interlayer with either a tougher material or through the use of preformed particles, leading to the third generation of composite materials. This chapter discusses the development, processes, application, advantages, and disadvantages of dispersed-phase toughening of thermoset matrices. Information on the processes of particle interlayer toughening of composite materials is also included.

Ceramic-matrix composites possess many of the desirable qualities of monolithic ceramics, but are much tougher because of the reinforcements. This chapter explains how reinforcements are used in ceramic-matrix composites and how they alter energy-dissipating mechanisms and load-carrying behaviors. It compares the stress-strain curves for monolithic ceramics and ceramic-matrix composites, noting improvements afforded by the addition of reinforcements. It then goes on to discuss the key attributes, properties, and applications of discontinuously reinforced ceramic composites, continuous fiber ceramic composites, and carbon-carbon composites. It also describes a number of ceramic-matrix composite processing methods, including cold pressing and sintering, hot pressing, reaction bonding, directed metal oxidation, and liquid, vapor, and polymer infiltration.

This chapter provides a general description of materials and methods for manufacturing high-performance composites. The materials covered are polymer matrices and prepreg materials and the methods include infusion processes, composite-toughening methods, matrix-toughening methods, and dispersed-phase toughening. In addition, the chapter provides information on interlayer-toughened composites and honeycomb or foam structure composite materials. It also discusses the processes in optical microscopy of composite materials.

This chapter discusses the use of thermoset and thermoplastic resins in polymer matrix composites. It begins by explaining how the two classes of polymer differ and how it impacts their use as matrix materials. It then goes on to describe the characteristics of polyester, vinyl ester, epoxy, bismaleimide, cyanate ester, polyimide, and phenolic resins and various toughening methods. The chapter also covers thermoplastic matrix materials and product forms and provides an introduction to the physiochemical tests used to characterize resins and cured laminates.

This chapter discusses the properties and uses of fiber-reinforced composites. It also describes the effect of volume fraction and fiber length.

This chapter discusses the types of fibers and matrix materials used in ceramic matrix composites and the role of interfacial coatings. It describes the methods used to produce ceramic composites, including powder processing, slurry infiltration and consolidation, polymer infiltration and pyrolysis, chemical vapor infiltration, directed metal oxidation, and liquid silicon infiltration.

This chapter discusses the composition, alloying characteristics, mechanical properties, corrosion resistance, advantages, limitations, and applications of martensitic, semiaustenitic, and austenitic precipitation-hardenable stainless steels.

This chapter discusses the failure mechanisms associated with fiber-reinforced composites. It begins with a review of fiber-matrix systems and the stress-strain response of unidirectional lamina and both notched and unnotched composite laminate specimens. It then explains how cyclic loading can lead to delamination, the primary failure mode of most composites, and describes some of the methods that have been developed to improve delamination resistance, assess damage tolerance, determine residual strength, and predict failure modes.

This article discusses the effects of alloying on the properties and behaviors of maraging steels. It describes how maraging steels differ from conventional steels in that they are strengthened, not by carbon, but by the precipitation of intermetallic compounds. It explains how maraging steels typically have high levels of nickel, cobalt, and molybdenum with little carbon content and how that affects their dimensional stability, fracture toughness, weldability, and resistance to stress-corrosion cracking.

This article discusses the production, properties, and uses of high-alloy white irons. It explains how the composition and melt are controlled to produce a large volume of eutectic carbides, making these irons particularly hard and resistant to wear, and how the metallic matrix supporting the carbide phase can be adjusted via alloy content and heat treatment to optimize the balance between abrasion resistance and impact toughness. It also describes the effect of alloying elements and inoculants on various properties and behaviors and provides information on commercial alloy grades and applications.

This appendix contains abbreviations and symbols related to aluminum alloy castings.

Engineers have many materials to choose from when dealing with weight-related design constraints. The list includes aluminum, beryllium, magnesium, and titanium alloys as well as engineering plastics, structural ceramics, and polymer-, metal-, and ceramic-matrix composites. This chapter provides a brief overview of these lightweight materials, discussing their primary advantages along with their properties, behaviors, and limitations.

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.

The commercial relevance of cast irons is best understood in the context of the iron-carbon phase diagram, where their composition places them near the eutectic point, which sheds light on why they melt at lower temperatures than steel and why they can be cast into more intricate shapes. This chapter examines these unique properties and how they are derived. It begins by describing the basic metallurgy of cast iron, focusing on the eutectic reaction. It explains how to control the reaction and thus properties of cast iron by overcooling and inoculation. The chapter also discusses composition, microstructure, heat treatments, and the classification and casting characteristics of white, gray, ductile, malleable, compacted graphite, and special cast irons.

High-speed tool steels have in common the ability to maintain high hardness at elevated temperatures. High speed steels are primarily used for cutting tools that generate heat during high-speed machining. They are designated as group M or group T steels in the AISI classification system, depending on whether the major alloying approach is based on molybdenum or tungsten. This chapter describes the effects of each of the alloying elements and carbon content on the processing, microstructures, and properties of high-speed steels. It discusses the processes involved in the solidification, hot work, annealing, austenitizing for hardening, and tempering of high-speed steels. It also discusses the processes involved in controlling grain size during austenitizing and reviews the characteristics of cooling transformations and other property changes in tempered high-speed steels. Information on multipoint cutting tools is provided. The chapter discusses the applications of high-speed tool steel and factors in selecting high-speed tool steels.

This article discusses the applications, compositions, and properties of cemented carbides and cermets. It explains how alloying elements, grain size, and binder content influence the properties and behaviors of cemented carbides. It also discusses the properties of steel-bonded carbides, or cermets, the various grades available, and the types of applications for which they are suited.

This chapter examines the static, fatigue, and damage tolerance properties of glass, aramid, and carbon fiber systems. It also explains how delaminations, voids, porosity, fiber distortion, and fastener hole defects affect impact resistance and strength.