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| Unique Visitors: 5 |
| Total Unique Visitors: 15437 |
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| Manufacturing Considerations |
| 2011-12-03 02:17:00 |
Composites also offer a number of significant manufacturing advantages over monolithic metals and ceramics. For example, fiber-reinforced polymers and ceramics can be fabricated in large, complex shapes that would be difficult or impossible to make with other materials.The ability to fabricate complex shapes allows consolidation of parts, which reduces machining and assembly costs. Some processes allow fabrication of parts to their final shape (net shape) or close to their final shape (near-net shape), which also produces manufacturing cost savings. The relative ease with which smooth shapes can be made is a significant factor in the use of composites in aircraft and other applications for which aerodynamic considerations are important.READ MORE.......Car...
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| Comparative Properties of Composite Materials |
| 2011-11-12 12:51:00 |
There are a large and increasing number of materials that fall in each of the four types of composites, making generalization difficult. However, as a class of materials, composites tend to have the following characteristics: high strength; high modulus; low density; excellent resistance to fatigue, creep, creep rupture, corrosion, and wear; and low coefficient of thermal expansion (CTE). As for monolithic materials, each of the four classes of composites has its own particular attributes. For example, CMCs tend to have particularly good resistance to corrosion, oxidation, and wear, along with high-temperature capability. For applications in which both mechanical properties and low weight are important,useful figures of merit are specific strength (...
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| Classes and Characteristics of Composite Materials |
| 2011-09-17 19:57:00 |
There is no universally accepted definition of a composite material. For the purpose of this work, we consider a composite to be a material consisting of two or more distinct phases, bonded together.1Solid materials can be divided into four categories: polymers, metals, ceramics, and carbon, which we consider as a separate class because of its unique characteristics. We find both reinforcements and matrix materials in all four categories. This gives us the ability to create a limitless number of new material systems with unique properties that cannot beobtained with any single monolithic material. Table 1 shows the types of material combinations now in use.Composites are usually classified by the type of material used for the matrix. The four primary cate...
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| COMPOSITE MATERIALS |
| 2011-09-13 09:09:00 |
INTRODUCTIONThe development of composite materials and related design and manufacturing technologies is one of the most important advances in the history of materials. Composites are multifunctional materials having unprecedented mechanical and physical properties that can be tailored to meet the requirements of a particular application. Many composites also exhibit great resistance to high-temperature corrosion and oxidation and wear. These unique characteristicsprovide the mechanical engineer with design opportunities not possible with conventional monolithic (unreinforced) materials. Composites technology also makes possible the use of an entire class of solid materials, ceramics, in applications for which monolithic versions are unsuited because...
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| What Are Titanium Alloys? |
| 2011-09-07 10:39:00 |
For purposes of this chapter titanium alloys are those alloys of about 50% or higher titanium that offer exceptional strength-to-density benefits plus corrosion properties comparable to the excellent corrosion resistance of pure titanium. The range of operation is from cryogenic temperatures to around 538–595 C (1000–1100 F). Titanium alloys based on intermetallics such as gamma titanium aluminide (TiAl intermetallic compound which has been designated ) are included in this discussion. These alloys are meant to compete with superalloys at the lower end of superalloy temperature capability, perhaps up to 700 C ( 1300 F). Theymay offer some mechanical advantages for now but often represent an economic debit.Limited experience is available with the tit...
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| cork removers |
| 2011-04-10 17:32:00 |
Figure 2.9 shows examples of using these worlung principles. All are describedby the function structure sketched in the upper part of Figure 2.10: create a force, transmit aforce, apply force to cork. They differ in the working principle by which these functions areachieved, as indicated in the lower part of Figure 2.10. The cork removers in the photos combineworking principles in the ways shown by the linking lines. Others could be devised by makingother links.Figure 2.11 shows embodiment sketches for devices based on just one concept -that of axialtraction. The first is a direct pull; the other three use some sort of mechanical advantage -leveredpull, geared pull and spring-assisted pull; the photos show examples of all of these.The embodiments of Figure 2.8 identify the functional requi...
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| Devices to open corked bottles |
| 2011-04-07 09:33:00 |
Wine, like cheese, is one of man’s improvements on nature. And ever since man has cared about wine, he has cared about cork to keep it safely sealed in flasks and bottles. ‘Corticum.. . demovebit amphorae. . .’ - ‘Uncork the amphora.. .’ sang Horace* (27 BC) to celebrate the anniversary of his miraculous escape from death by a falling tree. But how did he do it?A corked bottle creates a market need: it is the need to gain access to the wine inside. We might state it thus: ‘a device is required to pull corks from wine bottles’. But hold on. The need must be expressed in solution-neutral form, and this is not. The aim is to gain access to the wine; our statement implies that this will be done by removing the cork, and that it will be removed by pulling. There could be other way...
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| Function, material, shape and process |
| 2011-03-29 19:38:00 |
The selection of a material and process cannot be separated from the choice of shape. We use the word 'shape' to include the external shape (the macro-shape), and -when necessary -the internal shape, as in a honeycomb or cellular structure (the micro-shape). The achieve the shape, the material is subjected to processes which, collectively, we shall call manufacture: they include primary forming processes (like casting and forging), material removal processes (machining, drilling), finishing processes (such as polishing) and joining processes (welding, for example). Function, material, shape and process interact (Figure 2.5). Function dictates the choice of both material and shape.Process is influenced by the material: by its formability, machinability, weldability, heat-treatability and so...
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| Types of design |
| 2011-03-20 17:22:00 |
It is not always necessary to start, as it were, from scratch. Original design does: it involves anew idea or working principle (the ball-point pen, the compact disc). New materials can offer new, unique combinations of properties which enable original design. High-purity silicon enabled thetransistor; high-purity glass, the optical fibre; high coercive-force magnets, the miniature earphone. Sometimes the new material suggests the new product; sometimes instead the new product demands the development of a new material: nuclear technology drove the development of a series of newzirconium-based alloys; space technology stimulated the development of lightweight composites; turbine technology today drives development of high-temperature alloys and ceramics. Adaptive or development design takes...
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| The design process |
| 2011-03-14 10:31:00 |
Introduction and synopsisIt is mechanical design with which we are primarily concerned here; it deals with the physical principles, the proper functioning and the production of mechanical systems. This does not mean that we ignore industrial design, which speaks of pattern, colour, texture, and (above all) consumer appeal - but that comes later. The starting point is good mechanical design, and the role of materials in it.Our aim is to develop a methodology for selecting materials and processes which is design-led; that is, the selection uses, as inputs, the functional requirements of the design. To do so we must first look briefly at design itself. Like most technical fields it is encrusted with its own special jargon; it cannot all be avoided. This chapter introduces some of the words an...
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