bluuebunny/crossref_metadata_2025 huggingface dataset:
Fracture Mechanics
Authors: Kolednik Otmar
Published: July 2012

Fracture mechanics is a continuum mechanics tool for the description of the behavior of cracks in materials and components. The text concentrates on the fundamental understanding of the various parameters that are applied to characterize the crack driving force and the fracture resistance and outlines their physical meanings and their limitations. Then a few important topics are presented, such as the influence of geometry and size on the crack growth resistance, the conditions for unstable crack growth, and the prediction of the crack path. The final focus is the behavior of cracks in inhomogeneous materials, such as composites. Especially interesting here is the understanding, how spatial material property variations influence the crack driving force, since this opens the door for materials and components design, that is, to optimize materials by intentional variations of the material properties so that the fracture resistance increases.
FRP‐Reinforced Concrete Structures
Authors: De Luca Antonio , Nanni Antonio
Published: July 2012

This article covers the use of fiber‐reinforced polymer (FRP) as internal reinforcement in concrete structures. Mechanical and durability properties of both concrete and FRP bars are introduced; design concepts for reinforced concrete (RC) structures with internal FRP reinforcement are then presented and discussed. An overview of available test methods for the mechanical and durability characterization of both concrete and FRP bars and current guides for the design of FRP‐RC structures is provided. This article concludes with a list of examples of real field applications.
FRPStructural Profiles and Shapes
Authors: Pecce Marisa , Cosenza Edoardo
Published: July 2012

The pultrusion process allows the manufacture of profiles and shapes characterized by interesting properties that compete with those of traditional materials, such as lightness and durability. The material obtained is anisotropic and quite elastic up to failure. The mechanical properties present a high ratio of strength to elastic modulus, making deformability and buckling meaningful aspects of the structural behavior. Here, the various features are introduced, with many references to the current literature. The importance of the high shear deformability of a material on the element deformability is explained trough an experimental example. The most common failure mode of pultruded profiles is buckling, which can be global or local according the slenderness of the element and the subcomponents of the section (flange and web); also, the interaction between the two types of buckling can be taken into account by a well‐known approach based on a single relation between the element slenderness and the buckling load. Further, the design approaches and guidelines are discussed, underlining the fact that it is necessary to extend the design factors usually suggested by manufacturers so as to have reliable values for a general approach.

Some information about systems for bridge decks are presented that can have various shapes of the transverse section. Finally, applications are briefly described.
Helicopter Composite Materials Applications: Rotors
Authors: Scapinello Francesco
Published: July 2012

Rotors are the systems allowing helicopters to flight, providing lift, and directional thrusts. Composite materials are nowadays widely used in rotor components construction and, namely, for blades and hubs. Typical applications are described. The evolution in the usage of fibrous composites from the simple substitution of metals to the current exploitation of peculiar characteristics is evaluated. The scenario of application for other nonfibrous composite materials is also considered. Other aspects such as design for manufacturing and airworthiness requirements are considered.
History of Composites in Aeronautics
Authors: Palmer Raymond J.
Published: July 2012

Composite material applications for aeronautics have increased from a laboratory curiosity in 1970 to a full‐scale useful production ready position in the past 40 years. Advanced high modulus composites developed when man‐made fibers of high strength and stiffness became available. A discussion on the history of the development of fiberglass, Kevlar, boron, and carbon fibers is presented. A representative survey of application and use of composites in military, commercial, business and regional aircraft, and helicopters includes a discussion on the growth of composites in each group and suggestions on the future aircraft performance and composite applications. The survey discusses the operating features and the use and amount of composites on individual aircraft. The conclusion gives projected plans for the future of the industry.
Problems and Fundamental Models for Inverse Methods in Composite Materials
Authors: Fraldi Massimiliano
Published: July 2012

Inverse problems form an essential mathematical apparatus for dealing composite materials. They allow to derive the macroscopic behavior of complex heterogeneous media from the knowledge of their physical properties and geometrical features exhibited at the microscale level, thus being at the basis of design strategies for conceiving new materials in which selected electromagnetic, thermo mechanical, or chemical performances can be drastically and helpfully enhanced. Self‐healing materials, bio‐inspired composites with encapsulated healing agents able to repair the damage, as well as nanocomposites, such as colloids, gels, copolymers and carbon nanotubes, are all main actors on the scene of materials science and engineering. All these issues are common to modeling and inverse problems and constitute three distinct mathematical problems:
homogenization, localization, and optimization
. Hence, these models and the related inverse problems form the topic of the present article, where after giving a concise introduction to the complementary theories of homogenization and localization, two relevant heuristic micromechanical models based on the engaging of microstructural fabric tensor measures are illustrated in detail, to analyze anisotropic nonhomogeneous porous media and hyperelastic fiber‐reinforced materials. In addition, remarkable analytical methods for solving elastic problems for composite materials and notes on promising issues on topology optimization problems have been finally discussed.
Joining: Thermoplastic Composites Fusion Bonding/Welding
Authors: Yousefpour Ali
Published: July 2012

As advanced composite structures become larger and more complex, there is a corresponding need to improve methods of joining and assembly. Current methods of joining composite materials for aerospace applications, that is, adhesive bonding and mechanical fastening, present some design and manufacturing limitations. The mechanical fastening method cannot be effectively applied to composite structures because of stress concentration, the effects of drilling on the structural integrity, and localized delamination. Poor bonding properties between adhesives and polymers make the adhesive bonding methods less desirable for most structural applications. The fact that thermoplastic materials can be remelted provides the opportunity of welding (or fusion bonding) of thermoplastic composite parts as an alternative to joining and assembly. Fusion bonding, in principle, consists of surface preparation, heating the polymer at the weld interface to a viscous state, physically causing polymer chains to interdiffuse across the interface, and cooling the polymer for consolidation. The polymer chains are intertwined across the interface during the welding process, resulting in disappearance of the bonded surface and improving the ability of transferring loads through the welded area. The quality of the welded parts is usually compared to that of autoclave consolidated or compression molded parts.
Laminates Progressive Failure Analysis: Recent Approaches Based on Finite Element Analysis Techniques
Authors: Lecce Leonardo , Monaco Ernesto , Ricci Fabrizio
Published: July 2012

Fiber‐reinforced composites, with their high strength‐to‐weight ratio, are finding increasing use in primary structural components in many aerospace applications. They offer excellent in‐plane performances, but the poor properties in, the through‐thickness direction make composite materials particularly susceptible to severe out‐of plane loads, such as transverse low velocity impacts. A low velocity impact event typically causes significant, but barely visible, damage in terms of initial matrix cracking, followed by delaminations and eventually fiber breakage; so it is one of the most subtle threat to composite materials and a major issue in the design of laminated composite structures, which has, received much attention in recent years. Progressive failure analysis (PFA) is probably the most promising approach to understand the mechanism of damage progression in composite materials. PFA has been implemented in many finite element commercially available codes. In this article, failure and progressive failure modeling approaches are reviewed.
Manufacture of Polymer Composites
Authors: Grove Stephen
Published: July 2012

This article provides a summary of the alternative manufacturing methods available for fiber‐reinforced polymer composites and the factors that influence their selection. Both thermoset and thermoplastic composites are considered, but an article of this length can only give an overview of what is a complex field of many different technologies. Postmolding operations, such as machining, joining, and repair, are beyond the scope of this article; the reader is referred to the bibliography and to other relevant materials available in this encyclopedia for more information.
Metal Matrix Composites: Casting Processes
Authors: Previtali Barbara
Published: July 2012

This article deals with the casting processes of metal matrix composites (MMCs). First, a common definition of MMCs and a classification of main MMC casting routes are given. Then the main casting processes are described, with particular attention to the changes that have to be introduced in order to take into account the peculiar characteristics of MMCs. Finally, the principal and well‐recognized applications in casting MMCs are reported, as well as future developments and challenges.
Metal Matrix Composites: Corrosion
Authors: Salvago Gabriele , Bestetti Massimiliano
Published: July 2012

Metal matrix composites (MMCs) are important materials usually designed for applications where the mechanical performances are the most important technical requirements. Nowadays, the applications of MMCs are not only limited to automotive and aerospace industries but also they are widespread into other industries. In this respect, it becomes important to take into account also the corrosion resistance behavior of MMCs, in relation to different factors, such as metal matrix composition and microstructure, particles composition, size, and dispersion, environments where MMCs are used. This article is a comprehensive literature review on the corrosion mechanisms and the methods used to prevent corrosion for the most important types of MMCs. In this article, different metal matrices are considered, by taking into account generally active ones (Mg), those with amphoteric characteristics (Al, Zn), noble metal matrices with film‐forming corrosion products (Cu), and those that form passivation layers affected by chlorides (steel, Ni), and finally metal matrices with stable passivity (Ti).
Metal Matrix Composites: Discontinuously Reinforced, Microstructure and Mechanical Property Correlations
Authors: Gariboldi Elisabetta
Published: July 2012

In discontinuously reinforced metal matrix composites, pure metal or alloy matrices are typically reinforced by means of particles, whiskers, and short fibers, although the use of other reinforcement geometries is possible. The microstructural features characterizing a discontinuously reinforced composite (DRC) have been grouped and discussed as matrix, reinforcement, or interface features in this article. The correlations between them and the mechanical properties of the composites have been addressed by dealing with specific materials and micromechanical models as examples. Among material properties, the focus is mainly on the mechanical ones. With the help of an example, it was shown that, since the elastic modulus of a DRC is mainly related to the elastic properties of the matrix and reinforcement as well as to the geometry, it can be relatively easily predicted and controlled during material fabrication and processing. On the other hand, the yield strength is additionally related to other microstructural features, for example, the matrix grain size, and it is thus severely affected and can be considerably improved by optimized DRC fabrication and processing steps, but it cannot be easily predicted without taking the process parameters into account. Lastly, a number of mechanical properties correlated to local or general rupture, such as UTS, fatigue properties, creep rupture times, are affected by the onset and evolution of microstructural damage, since damage alters load transfer conditions. Therefore, a part of the article focuses on mechanisms of microstructural damage and on the interesting models proposed in literature to link it to microstructural features.
Metal Matrix Composites: Infiltration
Authors: Wannasin Jessada , Flemings Merton C.
Published: July 2012

Infiltration process is one of the major processes used to produce metal matrix composites for several applications. This article reviews and discusses various infiltration processes, reinforcement types, important process fundamentals, and the advantages, limitations, and applications of infiltration.
Metal Matrix Composites: Magnesium
Authors: Luthringer Bérengère J. C. , Hort Norbert , Feyerabend Frank
Published: July 2012

In this article, special attention is drawn to magnesium‐based metal matrix composites (MMCs). The first part reviews the conventional and the newer processing techniques appropriate for the fabrication of magnesium matrix composites. These routes are divided into liquid‐ and solid‐state fabrication,in situ, and spray forming methods. After introducing the matrix and its properties, reinforcements are described (continuous and discontinuous) and the obtained composites are discussed. The interface is also described. Finally, recent applications, such as medical purpose, are reported.
Micromechanisms of Delamination in Composite Materials Induced by Drilling
Authors: Hocheng Hong , Tsao Chung Chen
Published: July 2012

Drilling is the mostly used secondary machining of the fiber‐reinforced composite laminates, while the delamination around the drill hole occurs frequently during machining. Hole quality is a curb aspect for all hole‐making processes used on composite materials, which can affect the in‐service life under fatigue loads. Numerous studies have been elucidated that delamination is mainly effected by the drill geometry and drilling parameters. Thrust force has been considered as the cause of delamination by several researchers, and it is believed that there is a “critical thrust force” below which no damage occurs. This article presents a comprehensive analysis of delamination in use of various drills. These critical thrust forces at the onset of delamination are theoretically predicted and compared with the twist drill. In addition, the remedy and measurement of the drilling‐induced delamination were also discussed in detail and presented in this article.
Molding: Short‐Fiber Composites, Flow ProcessingAdapted fromMolding Short‐Fiber Composites, Flow Processing, First Edition.
Authors: Advani Suresh G.
Published: July 2012

A short‐fiber composite consists of a polymer matrix reinforced by fibers of much smaller length compared to the overall dimensions of the fabricated structure. These reinforced polymers were developed to fill the mechanical property gap between the continuous‐fiber laminates used as primary structures by the aircraft and aerospace industry and the neat polymers used in non‐load‐bearing applications. In particular, short‐fiber composites are handled as bulk suspensions and can be easily formed into complex‐shaped structures by processes such as transfer, compression, and injection molding. The molding processes for all short‐fiber systems involve a modest amount of flow through channels or mold cavities of different geometries. The complex microstructure and morphology that are produced depend on many parameters, such as the range of fiber lengths and diameters, fibers interaction with the mold walls and with each other during flow, heat transfer in the mold, and mold geometry. As the microstructure produced is related to the flow‐processing route of the fiber‐filled suspensions and the geometry of the mold, by exercising control over the flow processing, one can tailor the microstructure of the composite to the required application. So, in this article, a discussion on the rheology of fiber suspension, fiber orientation modeling, and fiber degradation during molding process is presented.
Micromechanical Modeling of Heterogeneous Materials at Finite Strain
Authors: Abadi Mohammad Tahaye
Published: July 2012

A micromechanical modeling procedure is presented to predict the effective mechanical properties of heterogeneous materials at finite strain. A repeating unit cell (RUC) is assumed to represent the microstructure of the heterogeneous materials. The response of RUC is evaluated for different equivalent macroscopic deformation fields considering the periodicity conditions on the deformation of RUC boundary surfaces. Volume averaging scheme is implemented to apply the local macroscopic deformation gradient tensor to the RUC assigned to the microstructure. On the basis of the energy balance, the local nominal stress tensor is determined as a function of the resultant forces applied on the boundary surfaces of RUC and initial surface area. A computational technique is subsequently developed to obtain the response of heterogeneous microstructures. To demonstrate the details of micromechanical technique, it is implemented to evaluate the response of heterogeneous materials such as elastomeric composites and metal matrix composites with different microstructures subjected to the axial, shear, and combined loadings. The performance is successfully verified by comparison of the deformation in the macroscopic level to the response of a homogenized cell. This micromechanics tool provides a powerful viable algorithm for the determination of nonlinear properties in continuum mechanics material characterization at finite strain.
Nanostructured Polymer Composites by Sol–Gel Method
Authors: Mascia Leno , Lavorgna Marino
Published: July 2012

The sol‐gel method for producing polymer nanocomposites is discussed in general terms and also with reference to modification of membranes, enhancing the performance of conventional composites and improving the properties of coatings. The modification of proton exchange membranes (Nafion types) has been made via two different routes, one involving the infusion of the silane precursors into an existing swollen membrane and the other where a new membrane is cast from a solution mixture of Nafion and a silane precursor. Further improvements in the performance of the silica‐modified Nafion membranes have been achieved through the introduction of SO
3
H groups in the siloxane domains. The silica modification of ion permeation membranes is discussed with reference to solid polyelectrolytes, whereas for gas separation membranes the emphasis has been placed on aspects related to both Henry's dissolution and Langmuir sorption arising from the mesoporosity of the siloxane domains.

The improvements in performance of conventional composites have been achieved in two ways: In one system, a hybrid polyimide‐silica coating is used to replace the existing size on the surface of glass fibers for use in epoxy matrix composites, and in the other a polyimide silica hybrid is used as the matrix of carbon‐fiber composites.

In the case of coatings, the introduction of co‐continuous silica domains in a standard epoxy resin system has beneficial effects not only in terms of mechanical properties but also by making it possible to use molybdate species within the siloxane domains, which enhances the corrosion resistance through the passivation of the iron oxide formed at the interface.
Phthalocyanine Matrix Resins and CompositesAdapted from
Phthalocyanine Matrix Resins and Composites
, First Edition.
Authors: Ting Robert Y.
Published: July 2012

Fiber‐reinforced composite materials are used for many advanced structural applications in order to achieve a substantial weight saving in the structures. Many of these applications involve a high temperature requirement that cannot be met by conventional matrix resin systems such as epoxy. In order to meet the requirements for a wide range of high temperature applications, such as adhesives, sealants, coatings and matrix resins, in the 1970s, new class of resins, called
phthalocyanines
, was developed These materials have been demonstrated to be promising candidates for advanced composite applications. In this article, the structure and properties of phthalocyanine resins are discussed. The development of a selected phthalocyanine resin for fiber‐reinforced composites is also described. Moreover, test results on the mechanical properties of composite samples are presented and compared with those of other popular composite systems.
Polyarylene Sulfide Matrix Resins and Composites
Authors: Zhong Jiachun , Liu Xiaobo
Published: July 2012

In this article, the research and development of high performance polyarylene sulfide (PAS) matrix resins and composites are introduced. The synthesis route and method of the major varieties of PAS resins are described in detail, such as polyphenylene sulfide, polyarylene sulfide sulfone, polyarylene sulfide ketone, polyarylene sulfide amide, and so on, and the properties of polymers and their composites are also presented in detail. Furthermore, we make a retrospect on the current problems of such materials and a prospect on the direction of future development in this article.
Polybutadiene Rubbers and ResinsAdapted from
Polybutadiene Rubbers and Resins
, First Edition.
Authors: Dreyfuss Peter
Published: July 2012

1,3‐Butadiene, CH
2
CHCHCH
2
, can be converted to a wide variety of polymeric materials such as noncrystallizing rubbers, highly crystalline plastics, liquid, castable resins, and so on. The variety of polybutadiene products arises from two sources: differences in molecular weight and differences in microstructure. Moderately high molecular weight polymers are solids, while low molecular weight polymers are liquid. Differences in microstructure determine the properties of both solids and liquids.

Properties of these polymers and some examples of processes for resin are discussed in this article. Moreover, some applications of polybutadiene‐based composites are presented, and at the end, some aspects on the toxicity of these resins are discussed.
Polymeric Composites: Heat TransferThis is a revision of an article of the same title by M. R. Tant and J. B. Henderson originally published in The International Encyclopedia of Composites, Stuart M. Lee, Ed., VCH Publishers, 1991.
Authors: Tant Martin R. , Stretz Holly A. , Ambuken Preejith
Published: July 2012

Heat transfer is quite important during the processing of polymer composites and nanocomposites, and very often is important during their application as well. The low thermal conductivity of these materials, as well as the energy involved in internal chemical reactions or changes in phase, results in specific effects on structure and properties that must be considered during design of both the composite material and the processing operation required to make it. In this article, we describe the basic mechanisms of heat transfer and the energy equation, the thermophysical properties of polymers and polymer composites that are important during their processing and application, the nature and effects of heat transfer during processing, and heat transfer in both low temperature and high temperature applications. Over the last 30 years, many advances have been made in the characterization and modeling of heat transfer in polymer composites and nanocomposites exposed to a high heat flux, such as in ablative applications or during exposure to fire. These advances will support the development of newer and more advanced polymer composites more aptly suited to the as yet unknown but sure‐to‐be demanding engineering applications of the future.
Polymeric Extrusion
Authors: Incarnato Loredana , Di Maio Luciano
Published: July 2012

In the field of composites, the extrusion operation is mostly used to perform the continuous blending and compounding of both miscible and immiscible polymers, for carrying out chemical reactions and to remove volatile substances from the polymeric stream before its shaping. In the following sections of this article, a fundamental survey on extrusion processes is provided with particular attention to the analysis of both single‐ and twin‐screw systems and their applications in composite technology. A basic theoretical analysis of the process is reported in order to highlight the fundamental process parameters and their relation to the quality and performance of products. Some examples of extrusion operations applied in the field of composite processing are provided, focusing on the mixing of particulate solids in thermoplastic polymers, including the nanocomposite issues.
Polyimides: Condensation
Authors: Ding Mengxian
Published: July 2012

Linear‐condensed polyimides as composite matrices were introduced in three parts. Polycondensation processes include three categories: imide ring formed in the polymerization process, polyimide formed by the reaction of monomers possessing imide rings, and polymerization by Diels‐Alder reaction from bismaleimide and a bisenphilics. Polyimides from isomeric dianhydrides describe the properties of the polyimides, particularly in
T
g
, and rheologic behavior and composites using linear polyimides as the matrix resin: six types of condensation polyimides used as composite matrices were introduced.
Polyimide Fibers, AromaticAdapted fromPolyimide Fibers, Aromatic, First Edition.
Authors: Chang Stephen Z. D. , Harris Frank W.
Published: July 2012

In the 1980s, one of the developments in high performance fibers was the use of aromatic heterocyclic polymers such as poly(p‐phenylene benzobisthiazole) (PBZT) and poly(p‐phenylene benzoxazole) (PBO).

Aromatic polyimides are known for their excellent thermal stability, chemical and solvent resistance, and light stability. Because of these outstanding properties, they are widely used as industrial films, coatings, adhesives, and moldings at high temperatures. In the first part of the article, the synthesis of aromatic polyimides are discussed, describing the one‐step method and the two‐step method. Moreover, a discussion on the basic technology for forming synthetic fibers, which includes spinning and heat treatment under drawing, is presented. In the second part of this article, structure, morphology, and different properties such as color, density, thermal stability, and so on of aromatic polymide fibers are presented.
Partially Fluorinated Polyimide Resins and Composites
Authors: Boyd Jack , Pratte James
Published: July 2012

The review article gives historical insight to the developments in this area and where future activities should focus on as the industry moves forward with high temperature materials in a few select applications. Processing of the latest generation of partially fluorinated polyimides has improved significantly over the earlier generation, which had limited adoption of these materials primarily in aeroengine applications. Yet, challenges still remain in achieving higher durability while increasing the temperature capabilities of these materials. The developments over the last 30 years and how the current commercial systems have resolved the earlier technical challenges are discussed. Recent research and development efforts are reviewed and briefly discussed in terms of how they will improve the processing and performance of these materials.
Polypivalolactone–Carbon Fiber CompositesAdapted fromPolypivalolactone‐Carbon Fiber Composites, First Edition.
Authors: Paul C. W. , Akkapeddi M. K. , Mares F.
Published: July 2012

In this article polypivalolactone ‐ carbon fiber composites are presented.

In particular the crystallinity of polypivalolactone (PPL) is higher than that of polyetherether ketone (PEEK)or polyphenylene sulfide (PPS) and this high value leads to far better strength, stiffness, solvent resistance, and temperature resistance than would be expected of a simple aliphatic polyester. This article describes techniques for prepregging PPL‐carbon and the mechanical properties of PPL‐carbon composites. Moreover a comparison between mechanical properties of PPL‐carbon composites with PEEK and PPS composites, and a comparison between the solvent resistance of PPL and PEEK neat resins are discussed.
Polyquinoxaline Matrix Resins and CompositesAdapted from
Polyquinoxaline Matrix Resins and Composites
, First Edition.
Authors: Hergenrother Paul M. , Connell John W.
Published: July 2012

Polyquinoxalines (PQs) are heterocyclic polymers that contain the heteroaromatic benzo [α] pyrazine (quinoxaline) ring along the main chain. They represent an important class of polymers that offer high chemical and thermal stability coupled with high mechanical properties. They are potentially useful as functional resins (e.g., films and coatings) and structural resins (e.g., adhesives and composite matrices) in many applications.

In this article, some neat resin properties such as thermal and mechanical properties are presented. The properties of the PQs can be altered by changing the chemical structure of the polymer backbone and also the chemical nature of the pendent group on the quinoxaline ring, and this unique feature provides versatility in designing PQs with an attractive combination of properties for use in specific applications, in particular, matrix resins in fiber‐reinforced composites.
Polyvinyl Chloride Composites
Authors: Sheng Kuichuan , Adl Mehrdad , Wang Hui , Qian Xiangqun
Published: July 2012

Polyvinyl chloride (PVC) as a thermoplastic polymer stands at the third rank after polyethylene (PE) and polypropylene (PP) among the most frequently used polymers in the world. This article reviews in brief the physical and mechanical properties of PVC and discusses the incorporation of other materials with it in order to prepare new products called
composites
. Emphasis of this article is on fibers as reinforcements for improvement of mechanical and physical properties of manufactured PVC composites. The most common parameters for qualitative evaluation of these composites have been summarized in this article. As PVC matrix and reinforcements may demonstrate rather poor compatibility and homogeneity in their natural form, a variety of coupling agents and surface modifiers are utilized to compensate these problems. A brief introduction to manufacturing techniques as well as market outlook of PVC composites is presented in the context of this article.
Processing of Biofiber‐Reinforced Composites
Authors: Faruk Omar , Bledzki Andrzej K.
Published: July 2012

Biocomposites from renewable resources have been attracting increasing attention over the last two decades, mainly for two major reasons: first, environmental concerns, and second, the realization that our petroleum resources are finite. Nowadays, biofiber‐reinforced composites are seen as potential materials for many engineering applications. Unfortunately, there are still issues that limit their future applications including long‐term performance and processing variability. This article gives an overview of the wide variety of biocomposite processing techniques as well as the factors (moisture content, fiber type, content as well as coupling agents, and their influence on composites properties) that affect the processes. Before processing biocomposites, semifinished product manufacturing is also a vital part, which is illustrated. Processing technologies for biofiber‐reinforced composites are discussed on the basis of the thermoplastic matrix (compression molding, extrusion, injection molding, LFT‐D method, and thermoforming) and thermosets (resin transfer molding, sheet molding compound) as well as other implemented processes, that is, thermoset compression molding and pultrusion. Furthermore, we include comparative studies between different processes regarding the biocomposites' structure–property relationships.
Project Management Considerations: Design Architectures for Civil and Military Aircraft
Authors: Gambino Benedetto
Published: July 2012

The historical evolution of the use of composite materials in actual aerospace vehicles is presented. The work emphasizes the application of composite structures in moderately to heavily loaded aerospace vehicles. Applications of composite materials are reviewed for large commercial transport aircraft, general aviation, and military aircraft.

Currently, a large variety of composite components are used in aircraft. An overview of the state of the art of advanced technologies and architectures is presented.

While significant improvements have occurred to structural analysis methodologies over the last two decades, the current structural design and analysis methodologies used by the aeronautics industry are still largely semiempirical. Very accurate finite element methods and sophisticated computer codes are used routinely to calculate the stress, strain, and displacement fields in complex structural geometries. State of the art of composites material simulation is presented.

An overview of certification of integrated/combined composite‐metallic primary airframe structure is presented.

The work is concluded with an evaluation of the future technology challenges associated with applications of composite materials to the primary and secondary structures of commercial aircraft.
Shells: Buckling Loads of Laminated Cylinders
Authors: Wetherhold Robert C.
Published: July 2012

Structural elements in the form of cylindrical shells are often designed to be thin to save weight, and this can lead to buckling. The patterns and values of buckling loads depend greatly on the type of loading, the end support conditions, and effective laminate material properties and couplings. For many typical buckling loadings, there is a variety of similar buckling states, which causes sensitivity to initial imperfections. Understanding this phenomenon requires the consideration of nonlinear strain‐displacement relations, usually in the von Kármán form. In addition, shells of composite materials require deformation assumptions that permit transverse shear deformation. A review of the results obtained using theoretical techniques is given as well as finite element predictions and experimental observations. A very brief summary of references is given for the optimization of shell buckling loads and for the additional effects of stringer reinforcement, thermal loadings, and other topics.
Static Electricity and Aircraft
Authors: Gigliotti Katia
Published: July 2012

The accumulation of electrostatic charge, generating during flight on the outer surfaces of aircraft and inside aircraft piping systems, cannot be considered as an immediate danger for flight safety, but it has to be seriously prevented to avoid upset in flight communications and risks of explosion in fuel areas or during refueling operations.

An overview of the methods adopted in aircraft industry to eliminate or reduce the electrostatic charge accumulation on insulating surfaces is presented: the most used techniques consist in applying coatings containing metal particles, “thermal spraying” metallic powders, or wires on nonconductive materials. The use of lightning protections, such as metallic mesh and expanded metal foil, on nonconductive composites also limits the static charge buildup, but it is foreseeable that, in the near future, nanocomposites will replace traditional lightning and shielding protection because of the wide range of possible electrical charging quantity and types.

Another significant issue in aircraft life is the possible electrostatic charge accumulation during refueling operations: while the tires will discharge static electricity, because of the presence of carbon black within the rubber matrix, they are not relied on to earth the airframe; therefore, when buildup of static electricity is of concern, it is always important to use mechanical means to ground the aircraft.

Lastly, the static charge control methods for electrostatic‐discharge‐sensitive (ESDS) equipment handling are introduced; in particular, instructions to avoid potential electrostatic charge accumulation during production and assembling, which could be a hazard to personnel and can damage equipment, are listed.
Stitched Preforms,NCF
Authors: Himmel Norbert
Published: July 2012

In this article, the manufacture of dry fiber noncrimp fabrics (NCFs) and the effects of stitching on the geometrical, processing, and mechanical properties of NCF and their polymer matrix composites are described. The terminology used in the context of these products is described and the motivation to consider and use NCF as compared to other fiber products is outlined. The types of stitching used to produce NCF products and complex structural preforms, the effects of stitching on the NCF geometry, and available modeling approaches are presented. The characteristics of the liquid resin infusion process into NCF fabrics and dry fiber preforms are described. Furthermore, effects of stitching on the mechanical properties of composites with NCF reinforcement subjected to static, cyclic fatigue, creep, and high strain rate loading are presented. The article is concluded by a brief outline of simulation models for the prediction of NCF permeability, resin infusion, and mechanical properties.
Structural Natural Composites
Authors: Neves Nuno M.
Published: July 2012

Structural natural composites are synthesized and maintained by living organisms in mild conditions of temperature and pressure or in challenging aqueous saline environments unlike their synthetic counterparts, having remarkable properties. The study of the properties of bones, trees, or sea shells allows concluding that nature engineers materials with unusually high performance and particularly well adapted to the function in their native environments.

This article analyzes the structure and its relation with the properties in three examples of natural structural composites: wood, nacre, and bone. It is aimed with those examples to illustrate the hierarchical structure at several length scales and the high effectiveness of the materials solutions to overcome the limitations of the original properties of biologically derived materials. The detailed analysis of those structures gives valuable insights and inspiration to the development of new and high performance composites needed in many engineering applications.
Structures: Marine Sandwich
Authors: Mitra Nilanjan
Published: July 2012

Sandwich composite panels are being primarily utilized in many engineering sectors such as civil, infrastructure, mechanical, aerospace, marine, space, and nuclear industry primarily because of their high strength and stiffness to low weight ratio. This article considers primarily sandwich composite construction that is typically utilized in the marine industry. This article discusses the application areas of sandwich composite panels in the marine industry, material utilized as component materials for the sandwich composite construction, the manufacturing methodologies, the novel methodologies that are applied to sandwich composite construction, and different experimental procedures utilized for sandwich composite structures.
Surface Analysis
Authors: Weng Lu‐Tao , Chan Chi‐Ming
Published: July 2012

Surface analysis has played an important role in the development of many advanced materials, including composites. This article describes the principles and instrumentation of the three most widely used surface analysis techniques: X‐ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS). Applications of these techniques in composites have been highlighted using some typical examples published recently. The strengths and weaknesses of each technique as well as the precautions of using these techniques in composites have also been critically reviewed.
Testing: Methods for Strength Characterization of Woven Fabric Composites at Cryogenic Temperatures
Authors: Shindo Yasuhide , Fu Shao‐Yun
Published: July 2012

This article summarizes the current status of the characterization methods for the strength properties of woven composites at cryogenic temperatures. The double‐notch and short‐beam shear test methods are examined for evaluation of the cryogenic interlaminar shear strength of woven glass fiber‐reinforced polymer (GFRP) laminates. Tensile tests on various unnotched specimens are also discussed based on the results for the cryogenic tensile strength of woven GFRP laminates. In addition, a combined numerical‐experimental method using the open‐hole tensile test and finite element analysis was proposed to evaluate the composite tensile strength at cryogenic temperatures.
Thermoforming of Thermoplastics Matrix Composites
Authors: Greco Antonio , Gennaro Riccardo , Maffezzoli Alfonso
Published: July 2012

This review addresses thermoforming of thermoplastic matrix composites (TPCs) reinforced with long or continuous fibers and of sandwich panels obtained using TPCs as skins. Thermoforming is a very versatile class of processes, applied to the production of parts of different thickness, ranging from < 1 mm for neat polymers to several millimeters for TPCs. Thermoforming technologies are based on the simultaneous application of temperature and pressure to a composite sheet, which is forced against the surface of a mold and then rapidly cooled down to allow its extraction. Besides processes description, the review reports the mechanisms of consolidation accounting for TPCs' specific behavior associated with the very high matrix viscosity. Finally, a brief analysis of the most common process‐induced defects is presented. The latest technologies and materials developments as well as the future trends for TPC processing, either for mass production or for high technology applications, are envisaged.
Thermoset Resins
Authors: Chatterjee Amit
Published: July 2012

Thermosets are highly cross‐linked polymers that are cured or set using heat, pressure, light, microwave and/or, energy devices. This leads to high performance products for industry because of their high modulus, strength, durability, and resistance toward thermal stress and chemical attacks as provided by their high cross‐linking density. Within this contribution, a special emphasis was made on phenolics, epoxy, polyester, BMI, cyanoester, POSS, urethanes, flame‐retardant thermosets, nano‐poly‐petroleum‐based, and biobased thermosets.
Bio‐Based Chemistry for Polymeric Matrices
Authors: Cobror Sandro , Iannace Salvatore
Published: July 2012

Since the last decade, the whole world is facing a sharp increase in energy consumption in conjunction with a fast growth in world population and an increasing demand in emerging economies. The vast majority of energy sources are actually derived from fossil. Chemical industry also uses fossil sources, primarily oil and gas, both for the manufacturing of chemical products and base chemicals and also for its internal energy consumption.

Since late 1990s, according to the Kyoto protocol, a decision was taken to reduce greenhouse gas (GHG) emissions on a global basis. Consequently, many countries have started relevant processes to implement national policies ultimately aimed at reduction of GHG emissions, at improving energy security, and at less reliance on fossil fuels. According to those policies, resources with no or minimal environmental impact have been indicated as alternatives to fossil ones for energy production. Vegetable or animal biomasses can be an option provided that they do not compete with food or with feed because of lack of food availability in developing Countries and potential risk of unacceptable agricultural commodities price increase.

A new kind of chemistry, based on the use of natural renewable resources, such as vegetable biomasses, widely available, inexpensive and with marginal environmental impact, is developing. This so‐called “bio‐based chemistry” will contribute to address some of the main concerns of the chemical industry. The depletion of nonrenewable and polluting oil resources, the effect of chemicals on human health, and the increase evidence of global warming can be the drivers to boost a new positive trend in the future for the entire chemical industry. In particular, the development of novel polymeric matrices from renewable resources for bio‐based composites appears very attractive as demand is expected to grow rapidly and significantly in next decades.
Vinyl Ester Matrix Resins and CompositesAdapted from
Vinyl Ester Matrix Resins and Composites
, First Edition.
Authors: White Mary N. , Henson F. C.
Published: July 2012

This article discusses vinyl ester resins that are produced by the esterification of a polyfunctional epoxy resin with an unsaturated monocarboxylic acid, usually methacrylic or acrylic acid, in the presence of a polymerization inhibitor, followed by the addition of a polymerizable diluent, usually styrene. Their versatility makes them ideal for many fiber‐reinforced plastic (FRP) composite applications, such as complex structural automotive parts, mentioned in the article.

Structure–properties relationships, formulation, and cure at ambient and elevated temperature of vinyl ester resins are discussed. An introduction on the typical fabrication methods that include hand layup, spray‐up, filament winding, resin transfer molding (RTM), and pultrusion is presented, and finally, safety considerations and the effect of government regulations on their use are reported.
Woven Composite Structures
Authors: Canonico Paolo
Published: July 2012

The woven structure of a composite material represents the reinforcement phase of composite materials and defines the pattern and orientation of the fibers, which are responsible for the technical performances and aesthetic aspects as well. The most common woven structures are described, with the indication of the main properties and related application fields. Different materials (glass, graphite, and aramid) require different weaving techniques and machinery. The weaving processes and the main application fields for woven structure of different fabrics are analyzed. It is likely that in the near future, due to the consolidation of new molding techniques (such as resin infusion, RTM, etc.), the woven structures will play a fundamental role in the development of new generation composite materials and will help their consolidation at the industrial scale.