Technology & Engineering
Composite Classes
Composite classes in programming refer to classes that are composed of other classes or objects. This allows for the creation of more complex and specialized objects by combining the functionality of multiple classes. By using composite classes, developers can create modular and reusable code, leading to more efficient and maintainable software systems.
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11 Key excerpts on "Composite Classes"
eBook - ePubCarbon Nanotube Reinforced Composites
CNT Polymer Science and Technology
- Marcio Loos(Author)
- 2014(Publication Date)
- William Andrew(Publisher)
Some of the major advantages of composite materials are their high mechanical properties and low mass. Replacing steel components with composites can mean a reduction of up to 80% in mass. As a result, today we can find composite materials in the automotive, aerospace, civil, marine, and sports areas.2.2. The concept of composites
Broadly speaking, it is accepted that there are three criteria that must be satisfied before a material can be considered a composite. These criteria are as follows: • The properties of the composite should be markedly different from those of the constituents; • The constituents should be present in measurable (noticeable) proportions; • The different materials (phases) should be separated by an interface.There are several definitions for composite materials. In a broad sense, a composite material is made by combining two or more materials to provide a unique combination of properties . Composite materials may also be defined as materials made from two or more components with different compositions, structures, and properties that are separated by an interface . Yet another possible definition is that the term composite material refers to any solid material composed of more than one component where they are in separate phases . The last definition is broad and includes a wide variety of materials such as fiber-reinforced plastics, ordinary concrete, concrete reinforced with steel, polymers reinforced with particles, etc. However, this book will focus on polymer matrix composites reinforced with carbon nanotubes (CNTs). Therefore, when the term “composite” or “composite material” is used the definition envisioned is as follows: composites are materials composed of a solid matrix that surrounds and retains the reinforcement phase
eBook - PDFComposites Manufacturing
Materials, Product, and Process Engineering
- Sanjay Mazumdar(Author)
- 2001(Publication Date)
- CRC Press(Publisher)
Ceramics cannot be processed by common metal- lurgical techniques and require high-temperature equipment for fabrication. Due to their high hardness, ceramics are difficult to machine and therefore require net-shape forming to final shape. Ceramics require expensive cutting tools, such as carbide and diamond tools. 1.1.4 Composites Composite materials have been utilized to solve technological problems for a long time but only in the 1960s did these materials start capturing the attention of industries with the introduction of polymeric-based composites. Since then, composite materials have become common engineering materials and are designed and manufactured for various applications including automotive 4 Composites Manufacturing: Materials, Product, and Process Engineering components, sporting goods, aerospace parts, consumer goods, and in the marine and oil industries. The growth in composite usage also came about because of increased awareness regarding product performance and increased competition in the global market for lightweight components. Among all materials, composite materials have the potential to replace widely used steel and aluminum, and many times with better performance. Replacing steel components with composite components can save 60 to 80% in component weight, and 20 to 50% weight by replacing aluminum parts. Today, it appears that composites are the materials of choice for many engi- neering applications. 1.2 What Are Composites? A composite material is made by combining two or more materials to give a unique combination of properties. The above definition is more general and can include metals alloys, plastic co-polymers, minerals, and wood. Fiber-reinforced composite materials differ from the above materials in that the constituent materials are different at the molecular level and are mechan- ically separable. In bulk form, the constituent materials work together but remain in their original forms.
eBook - ePub- George Staab(Author)
- 2015(Publication Date)
- Butterworth-Heinemann(Publisher)
1Introduction to composite materials
Abstract
This chapter contains a brief summary of the history of composite materials including the relative importance of four classes of materials (metals, polymers, ceramics, and composites) from 10,000 BC through 2200. A general description of the characteristics of composites as they pertain to isotropic, anisotropic, and orthotropic materials is presented along with various composite material classifications. The terminology associated with laminated composite materials analysis as well as a brief discussion of the advantages of using composites is presented along with representative examples of tensile strength and elastic modulus for selected fibers. The chapter concludes with a presentation of selected manufacturing techniques applicable to composite materials.Keywords Fibrous Particulate Lamina Laminate Reinforcements Fibers Matrix Hybrid Micromechanics Macromechanics Isotropic Orthotropic Anisotropic1.1 Historic and introductory comments
In the most general of terms, a composite is a material which consists of two or more constituent materials or phases. Traditional engineering materials (steel, aluminum, etc.) contain impurities which can represent different phases of the same material and fit the broad definition of a composite, but are not considered composites because the elastic modulus or strength of each phase are nearly identical. The definition of a composite material is flexible and can be augmented to fit specific requirements. In this text, a composite material is considered to be the one which contains two or more distinct constituents with significantly different macroscopic behavior and a distinct interface between each constituent (on the microscopic level). This includes the continuous fiber-laminated composites of primary concern herein, as well as a variety of composites not specifically addressed.Composite materials have been in existence for many centuries. No record exists as to when people first started using composites. Some of the earliest records of their use date back to the Egyptians, who are credited with the introduction of plywood, paper mache, and the use of straw in mud for strengthening bricks. Similarly, the ancient Inca and Mayan civilizations used plant fibers to strengthen bricks and pottery. Swords and armor were plated to add strength in medieval times. An example is the Samurai sword, which was produced by repeated folding and reshaping to form a multilayered composite (it is estimated that several million layers could have been used). Eskimos use moss to strengthen ice in forming igloos. Similarly, it is not uncommon to find horse hair in plaster for enhanced strength. The automotive industry introduced large scale use of composites with the 1953 Chevrolet Corvette. All of these are examples of man-made composite materials. Bamboo, bone, and celery are examples of cellular composites which exist in nature. Muscle tissue is a multidirectional fibrous laminate. There are numerous other examples of both natural and man-made composite materials.
eBook - PDF- David Williams(Author)
- 2014(Publication Date)
- Cambridge University Press(Publisher)
It is for this reason that we have a new major class of material (and hence biomaterial), which we shall designate Class 5 and call these materials composites. The classical derivation of composites comes from the need to strengthen polymers and/or toughen ceramics. Polymers deform plastically too easily and they are relatively weak, but they can show prodi- gious ductility simply because they deform so read- ily. Ceramics have no intrinsic mechanism for plastic deformation and will much rather undergo brittle fracture than plastic deformation. However, their interatomic bonds are very strong so that very high levels of stress are required before the structure fractures, that is, it can be very strong, even if it has zero ductility. If, however, we take a ductile but weak polymer, and disperse ceramic particles within it, then the particles resist the polymer plasticity and the polymer matrix deflects or stops cracks in the cer- amic, and the result is a strong and ductile material. Clearly, this is neither a polymer nor a ceramic system, but a composite, in this case a polymer– ceramic composite. Composites, by definition, are materials made from two entirely different structures where the best properties of each are retained, and the worse properties are lost. There are many forms of composite depending on the relationships between the phases. In theory, we could consider different sub-classes of composite depending on the two (or possibly more) phases that are present (perhaps polymer–ceramic, ceramic–carbon, carbon–poly- mer), but in this case such a classification principle does not really work, since the biomaterials applica- tions of composites depend on the required proper- ties.
- F L Matthews, G A O Davies, D Hitchings, C Soutis(Authors)
- 2000(Publication Date)
- Woodhead Publishing(Publisher)
Also some features of composite construction, such as filament winding, cannot easily be represented (if at all) by some FE packages. Following a review of com-posites and the FE method, the application of the method to composites is discussed in detail. The particular issues are then illustrated via a number of examples taken from particular situations. Overview 5 2 Fundamentals of composites 2.1 Basic characteristics 2.1.1 Definitions and classification A composite is a mixture of two or more distinct constituents or phases. In addition three other criteria are normally satisfied before we call a ma-terial a composite. Firstly, both constituents have to be present in reason-able proportions. Secondly, the constituent phases should have distinctly different properties, such that the composite’s properties are noticeably different from the properties of the constituents. Lastly, a synthetic composite is usually produced by deliberately mixing and combining the constituents by various means. We know that composites have two (or more) chemically distinct phases on a microscopic scale, separated by a distinct interface, and it is important to be able to specify these constituents. The constituent that is continuous and is often, but not always, present in the greater quantity in the compo-site is termed the matrix. The normal view is that it is the properties of the matrix that are improved upon when incorporating another constituent to produce a composite. A composite may have a ceramic, metallic or poly-meric matrix. The mechanical properties of these three classes of material differ considerably. As a generalisation, polymers have low strengths and Young’s moduli, ceramics are strong, stiff and brittle, and metals have inter-mediate strengths and moduli, together with good ductilities, i.e. they are not brittle. Because of their economic importance, the emphasis in this text will be on polymer matrix composites (PMCs).
- Rajiv Asthana, Ashok Kumar, Narendra B. Dahotre(Authors)
- 2006(Publication Date)
- Butterworth-Heinemann(Publisher)
6 Composite Materials Definition and Classification Composite materials are material systems that consist of a discrete constituent (the rein- forcement) distributed in a continuous phase (the matrix) and that derive their distinguishing characteristics from the properties and behavior of their constituents, from the geometry and arrangement of the constituents, and from the properties of the boundaries (interfaces) between the constituents. Composites are classified either on the basis of the nature of the continu- ous (matrix) phase (polymer-matrix, metal-matrix, ceramic-matrix, and intermetallic-matrix composites), or on the basis of the nature of the reinforcing phase (particle reinforced, fiber reinforced, dispersion strengthened, laminated, etc.). The properties of the composite can be tailored, and new combinations of properties can be achieved. For example, inherently brittle ceramics can be toughened by combining different types of ceramics in a ceramic-matrix com- posite, and inherently ductile metals can be made strong and stiff by incorporating a ceramic reinforcement. It is usually sufficient, and often desirable, to achieve a certain minimum level of reinforce- ment content in a composite. Thus, in creep-resistant dispersion-strengthened composites, the reinforcement volume fraction is maintained below 15% in order to preserve many of the useful properties of the matrix. Other factors, such as the shape, size, distribution of the reinforcement, and properties of the interface, are also important. The shape, size, amount, and type of the rein- forcing phase to be used are dictated by the combination of properties desired in the composite.
eBook - ePub- Ever J. Barbero(Author)
- 2017(Publication Date)
- CRC Press(Publisher)
Chapter 2Materials
Composite materials are formed by the combination of two or more materials to achieve properties (physical, chemical, etc.) that are superior to those of its constituents. The main components of composite materials, or composites, are fibers and matrix. The fibers provide most of the stiffness and strength. The matrix binds the fibers together thus providing load transfer between fibers and between the composite and the external loads and supports. Also, it protects the fibers from environmental attack. Other substances are used to improve specific properties. For example, fillers are used to reduce the cost and improve processability and dimensional stability [50 ].The design of a structural component using composites involves simultaneous material and structural design. Unlike conventional materials (e.g., steel), the properties of the composite material can be designed simultaneously with the structural aspects. Composite properties (e.g., stiffness, thermal expansion, etc.) can be varied continuously over a broad range of values, under the control of the designer. The objective of this chapter is to describe the constituents used in the fabrication of the composite material. The capabilities and limitations of various processing techniques used to fabricate the material and the parts are presented in Chapter 3 .A brief review of the most common types of materials used in the fabrication of composites is presented in this chapter, with emphasis on properties, advantages, disadvantages, and cost. No attempt is made to explain how fibers and polymers are produced; excellent material science books and handbooks cover that subject [51 –53 ]. Comprehensive lists of material suppliers can be found in specialized publications [54 ,55 ], trade associations [56 ,57 ], or the World Wide Web. Another important aspect of design and fabrication is to have standard test methods to verify the material properties used in design [58
eBook - PDF- George Murray, Charles V. White, Wolfgang Weise(Authors)
- 2007(Publication Date)
- CRC Press(Publisher)
1 1 Classification of Materials 1.1 INTRODUCTION Advancements in technology in most industries have been associated with the development of new materials and processes as well as advances in the state of the art of existing materials and combinations thereof. It is estimated that currently about 85,000 materials are available for industrial applications. In considering which materials to use for a particular structure or device, the selection process is further complicated by the wide variation in properties of materials with the manner in which the material is processed, for example, the heat treatment time, temperature, and cooling rate used for certain alloys. Some type of materials classification is an essential part of the selection process and an important element of engineering education. In the following sections, materials will be classified in the broad categories of metals, polymers, ceramics, composites, and semiconductors. In subsequent chapters, these materials and their associated processing methods will be pre-sented in more detail. In the design and material selection procedures, items such as the recycling potential of the material and environmental problems must be considered. 1.1.1 R ECYCLING Recycling is generally considered to be a part of solid waste management strat-egies. Any strategy devised must be incorporated in the material selection and design steps. Polymers are of much concern in recycling because many are nonbiodegrad-able and consist of about 20% of municipal solid waste. The thermoplastic polymers, which are easily formed and are abundant in packaging materials, have been given the most attention in terms of recycling technology. Representing about 90% of all plastics sold, they consist primarily of polyethylene, polyeth-ylene terephthalate (PET), polystyrene, polypropylene, and polyvinyl chloride (PVC).
eBook - PDFParts Fabrication
Principles and Process
- Richard Crowson(Author)
- 2006(Publication Date)
- CRC Press(Publisher)
229 Composite Manufacturing John F. Maguire with Don Weed and Thomas J. Rose 6.0 INTRODUCTION AND BACKGROUND It is difficult to find a truly satisfactory definition of composite material. The American Heritage Dictionary (Houghton Mifflin, Boston, 1981) comes close, with “a complex material, such as wood or fiber glass, in which two or more complementary substances, especially metals, ceramics, glasses, and polymers, combine to produce some structural or functional properties not present in any individual component.” The problem with even a good definition, of course, is that it is all-encompassing, so that every material in the universe could in some sense be defined as a composite. This loss of exclusivity diminishes the usefulness of the definition. For our purposes, we shall restrict attention to that subset of materials known as fiber-reinforced advanced polymeric composites. In these materials, a reinforcing fiber is embedded in an organic polymeric resin. The fiber acts as a structural reinforcement and the resin binds the fibers together. This transfers loads and provides structural and dimensional integrity. Advanced composite materials, developed in the latter half of the twentieth cen-tury, may well provide a key to enabling technology for the twenty-first century. These materials are strong, light, and corrosion resistant, offering considerable tech-nical advantages in aerospace, automotive, offshore petrochemical, infrastructure, and other general engineering applications. Composite components may be made by laminating or laying up layers of composite material, each ply consisting of one or more patterns, which may be as large as 4 1/2 ft wide by 9 ft long. These patterns are cut from a continuous roll of cloth, or from sheets, with standard widths measuring up to 4 1/2 ft. Composite material wider than 12 in. is referred to as broadgoods. If a material is narrower, it is usually a unidirectional tape. In such a tape the fibers run 6
- Ginu Rajan, B. Gangadhara Prusty(Authors)
- 2016(Publication Date)
- CRC Press(Publisher)
1 1 Introduction to Composite Materials and Smart Structures B. Gangadhara Prusty, Ebrahim Oromiehie, and Ginu Rajan 1.1 INTRODUCTION Composite structures are widely used in the aerospace, marine, aviation, transport, sport/leisure, and civil engineering industries [1]. In the past decade, advanced com-posite materials have been widely used in a variety of load-bearing structures such as rotor blades, aircraft fuselage, and wing skins [2]. For example, 52% by weight of the new Dreamliner and 25% by weight of the new Airbus A380 are made from composite materials. The unique properties of composite materials such as their high strength-to-weight ratio, high creep resistance, high tensile strength at elevated temperatures, and high toughness have been attracting increasing interest in numerous applications in different industries such as the automotive and aerospace industries [1,3]. It should be CONTENTS 1.1 Introduction ...................................................................................................... 1 1.2 Composite Materials: Structures and Types ..................................................... 2 1.2.1 Reinforcements ..................................................................................... 3 1.2.2 Matrix ................................................................................................... 4 1.3 Composite Manufacturing Methods and Technologies .................................... 6 1.3.1 Prepreg Layup Method ......................................................................... 6 1.3.2 Wet Layup Method ............................................................................... 7 1.3.3 Spray Layup Method ............................................................................ 8 1.3.4 Filament Winding Method ................................................................... 9 1.3.5 Pultrusion Method ..............................................................................
eBook - PDF- Marc André Meyers, Krishan Kumar Chawla(Authors)
- 2008(Publication Date)
- Cambridge University Press(Publisher)
Chapter 15 Composite Materials 15.1 Introduction We can define a composite material as a material consisting of two or more physically and/or chemically distinct phases, suitably arranged or distributed. A composite material usually has characteristics that are not depicted by any of its components in isolation. Generally, the continuous phase is referred to as the matrix , while the distributed phase is called the reinforcement . Three items determine the character-istics of a composite: the reinforcement, the matrix, and the interface between them. In this chapter, we provide a brief survey of different types of composite materials, highlight some of their important fea-tures, and indicate their various applications. 15.2 Types of Composites We may classify composites on the basis of the type of matrix employed in them --for example, polymer matrix composites (PMCs), metal matrix composites (MMCs), and ceramic matrix composites (CMCs). We may also classify composites on the basis of the type of reinforcement they employ (see Figure 15.1): 1. Particle reinforced composites. 2. Short fiber, or whisker reinforced, composites. 3. Continuous fiber, or sheet reinforced, MMCs. 4. Laminate composite. Figure 15.2 shows typical microstructures of some composites: boron fiber/Al (Figure 15.2(a)), short alumina fiber/Al (Figure 15.2(b)), and NbC/Ni--Cr, an in situ (eutectic) composite (Figure 15.2(c)). Examples of microstructure of a silicon carbide particle (three different volume fractions) reinforced aluminium matrix are given in Figure 15.3. These were made by hot pressing of powders followed by hot extrusion. Note the preferential alignment of SiC particles in the extrusion direction. 766 COMPOSITE MATERIALS (a) (b) (c) (d) Fig. 15.1 Different types of reinforcement for composites: (a) particle reinforcement; (b) short fiber reinforcement; (c) continuous fiber reinforcement; (d) laminate reinforcement (a) Fig.
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