Search Results for multiaxial carbon fibers

This article describes the manufacture, post-processing, fabrication, and properties of carbon-carbon composites (CCCs). Manufacturing techniques with respect to the processibility of different geometries of two-directional and multiaxial carbon fibers are listed in a table. The article discusses matrix precursor impregnants, liquid impregnation, and chemical vapor infiltration (CVI) for densification of CCCs. It presents various coating approaches for protecting CCCs, including pack cementation, chemical vapor deposition, and slurry coating. Practical limitations of coatings are also discussed. The article concludes with information on the mechanical properties of CCCs.

Open molding is the method used in the polymer-matrix composites industry to make thermoset composite products. This article discusses the advantages, disadvantages, and applications of the open molding. It describes the various process of the open molding, such as hand lay-up process and spray-up process. Workmanship for hand lay-up and spray-up processes is reviewed. The article provides information on the matrix-resin materials used for open molding, including unsaturated polyester resins, epoxy vinyl ester resins, and reinforcements. It explains the component design and short- and long-term properties of a fiber reinforced composite laminate depending on material selection and workmanship. The article also presents the basic design guidelines for open molding.

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.

Failure of structural polymeric materials under cyclic application of stress or strain is a subject of industrial importance. The understanding of fatigue mechanisms (damage) and the development of constitutive equations for damage evolution, leading to crack initiation and propagation as a function of loading or displacement history, represent a fundamental problem for scientists and engineers. This article describes the approaches to predict fatigue life and discusses the difference between thermal and mechanical fatigue failure of polymers.

Reinforcing fibers are a key component of polymer-matrix composites (PMCs), ceramic-matrix composites (CMCs), and metal-matrix composites (MMCs). This article discusses the mechanical and nonmechanical properties of these composites. It presents an overview of PMC, CMC, and MMC reinforcing fibers. The article describes cost-considered value-in-use of the ultimate-use temperature of selected fibers in three fiber categories: metal fibers or wires, oxide ceramic fibers, and non-oxide ceramic fibers.

This article describes the microcrack analysis of composite materials using bright-field illumination, polarized light, dyes, dark-field illumination, and epi-fluorescence.

This article reviews the common methods of shear and multiaxial testing for the evaluation of engineering components such as fasteners and mill products. It discusses shear test methods, including through-thickness tests, in-plane shear tests, and double-notched shear test. The article provides information on torsional (rotational shear) tests as well as the basic equipment and setup of torsion testing. Motors, twist and torque transducers, torque sensors, and heating systems as well as the specimen preparation procedure are also discussed.

The goal of micromechanics and analysis is to use the predictive methodology to develop tailored composites and also to make accurate predictions of their performance in service. This article reviews results derived from micromechanics analyses, based on finite-element method of unidirectional fiber reinforced metal matrix composites (MMCs). It discusses the elastic deformation and elastic-plastic deformation analysis of discontinuously reinforced MMCs. The article provides an overview of analysis of strength, fatigue, and fracture toughness for macromechanics fiber-reinforced and discontinuous reinforced composites.

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.

Carbon-carbon composites (CCCs) are introduced in fields that require their high specific strength and stiffness, in combination with their thermoshock resistance, chemical resistance, and fracture toughness, especially at high temperatures. The use of CCCs has expanded as the price of carbon fibers has dropped and their mechanical properties have increased. This article begins with an overview of the carbon conversion processes, fiber properties and microstructures, and interfacial bonding and environmental interaction of carbon fibers, followed by a detailed discussion on the various techniques available for processing CCCs for specific applications, including preform fabrication (fiber weaving), densification, application of protective coatings, and joining. The article closes with a description of the mechanical and physical properties and applications of CCCs. The main applications of CCCs, in terms of money and mass, are in the military, space, and aircraft industries.

Vacuum infusion is a resin injection technique derived from resin transfer molding. This article discusses the characteristics of the technique and its applications. It presents the theory and background of the technique and provides an illustration of how parts are made. The article provides information on the equipment and material used for vacuum infusion. It describes the mechanical properties of components and summarizes the influence of production on the properties. The article concludes with a discussion on design guidelines.

One of the key attributes of continuous fiber-reinforced ceramic composites (CFCCs) is their ability to undergo inelastic straining upon mechanical loading. This article reviews the mechanics of inelastic deformation and fracture of CFCCs, as needed for the development of damage-tolerant failure prediction methodologies for use in engineering design. It outlines a general framework for the description of fracture in structural materials in the presence of notches and cracks. The article describes the common classes of fracture behavior of CFCCs and presents the constitutive laws needed to describe crack-tip inelasticity. It demonstrates the effects of inelasticity on crack-tip stress fields and addresses the environmental degradation effects on damage tolerance.

This article describes common design criteria and identifies the design considerations that have a significant effect on the end product. The design criteria include cost, size, mechanical properties, repeatability and precision of parts, damage tolerance and durability, and environmental constraints.

Pultrusion is a cost-effective automated process for manufacturing continuous, constant cross-section composite profiles. This article describes the process characteristics and advantages of pultrusion. It provides information on the applications of pultrusion and discusses the processing equipment and tooling, the material composition, and the process control essential for a basic understanding of the pultrusion process.

Braided structures are unique in their high level of conformability, torsional stability, and damage resistance. This article describes the classifications of braiding such as two-dimensional braiding and three-dimensional braiding. It presents the governing equations for computer-controlled braiding in a table. The article lists the applications of braided fabrics and composites. It discusses the formation, structure, and properties of two-dimensional braid composites and three-dimensional braid composites: the damage tolerance and the impact damage limitation.

Ceramic-matrix composites (CMCs) are being developed for a number of high-temperature and high-performance applications in industrial, aerospace, and energy conservation sectors. This article focuses on processing, fabrication, testing, and characterization methods of CMCs, namely, discontinuously reinforced composites and continuous-fiber-reinforced composites. Processing methods include cold pressing, sintering, hot pressing, reaction bonding, melt infiltration, directed metal oxidation, sol-gel and polymer pyrolysis, self-propagating high-temperature synthesis and joining. A table summarizes the properties of various ceramic reinforcements and industrial applications of these composites.

In the design of composite structures for durability and damage tolerance, the primary concerns are out-of-plane failures, such as delamination, material degradation associated with environment, stability under compression loading, large degree of scatter in fatigue life, and bearing failure of joints. This article presents an introductory discussion on the fatigue damage process, methodologies assessing fatigue behavior, and life prediction models. It describes the damage mechanisms introduced for a quasi-isotropic laminate under tension-compression fatigue loading. Delamination is a critical issue in fatigue and generally results from high interlaminar normal and shear stresses. The article schematically illustrates the structural elements in which high interlaminar stresses are common. It concludes with a discussion on the classification of fatigue models such as mechanistic or phenomenological, for composite materials under cyclic loading.

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.

Of the many different nondestructive evaluation (NDE) techniques, ultrasonic inspection continues to be the leading nondestructive method for inspecting composite materials, because measurements can be quantitative and the typical defect geometries and orientations lend themselves to detection and characterization. This article focuses on the three common methods for ultrasonic nondestructive inspection of plastics, namely pitch-catch, through-transmission, and pulse-echo, as well as the three basic types of ultrasonic NDE scans: the A-scan, B-scan, and C-scan. The discussion includes the linear and phased array systems that are sometimes used for large-scale inspection tasks to reduce scan times, the various gating and image processing techniques, and how ultrasonic data are interpreted and presented. A brief section on future trends in ultrasonic inspection is presented at the end of the article.

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.