Có 140+ tài liệu thuộc chủ đề "thiết kế cơ khí"
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27.3 Control Synthesis for Biped Gait. 27.6 Conclusion. 27.1.1 Introduction. 27.1.2 The ZMP Notion. FIGURE 27.1 Single-support phase.. Substituting Equation (27.4) in Equation (27.6) yields:. 27.1.3 The Difference between ZMP and the Center of Pressure (CoP) One can see from the above analysis that ZMP is apparently equivalent to the center of pressure (CoP), representing the application point of the...
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28.1 Introduction 28.2 Industrial Robots. 28.3 Service Robots. 28.1 Introduction. In 1999 some 940,000 industrial robots were at work and major industrial countries reported growth rates in robot installation of more than 20% compared to the previous year (see Figure 28.1) The automotive, electric, and electronic industries have been the largest robot users. Robotics integrates the states of the art...
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We may think of the design as a mapping of the customer’s requirements into a physical embodiment. During the product specification and planning phase, we identify the customer’s requirements and translate them into engineering specifications in terms of the functional requirements and the time and money available for the development, and plan the project accordingly. In the product design phase,...
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For the (11, 10) graph shown in Figure 2.1a, e 23 is incident at vertices 2 and 3. The degree of a vertex is defined as the number of edges incident with that vertex.. For the graph shown in Figure 2.1a, the degree of vertex 2 is three, the degree of vertex 10 is one, and vertex 11 is an...
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The kinematic structure of a mechanism contains the essential information about which link is connected to which other link by what type of joint. The kinematic structure of a mechanism can be represented in several different ways. In this chapter various methods of representation of the kinematic structure of a mechanism or kinematic chain are described. For example, Figure 3.1...
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It is concerned primarily with the fundamental relationships among the degrees of freedom, the number of links, the number of joints, and the type of joints used in a mechanism. Although there are a few mechanisms whose corresponding graphs are not planar, these mechanisms usually contain a large number of links. A thorough understanding of the structural topology can be...
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Enumeration of Graphs of Kinematic Chains. Although this is somewhat arbitrary, in view of the complexity of such mechanisms, it is reasonable to exclude them. Pólya’s enumeration theorem provides a powerful tool for counting the number of graphs with a given number of vertices. and edges [7]. In this chapter we introduce several methods for the enumeration of contracted graphs...
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The classification problem can be transformed into an enumeration of nonisomorphic graphs for a prescribed number of degrees of freedom, number of loops, number of vertices, and number of edges.. The number of loops, number of links, and number of joints in a mechanism are re- lated by Euler’s equation, Equation (4.5). Since we are primarily interested in nonfractionated closed-loop...
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The chariot employed an ingenious differential gear train such that a figure mounted on top of the chariot always pointed to the south as the chariot was towed from one place to another. Figure 7.1 shows a compound planetary gear train commonly known as the Simpson gear set. The two sun gears are connected to each other by a common...
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In this chapter, we illustrate the usefulness of the systematic design methodol- ogy by enumerating a few automotive related mechanisms, including variable-stroke engine mechanisms, constant-velocity shaft couplings, and automatic transmission mechanisms.. Then, we translate some of the requirements into structural characteristics for the purpose of enumeration of the kinematic structures. Lastly, we apply the remaining functional requirements along with other...
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Major obsta- cles are some of the key technologies have not been fully developed. 9.2 Parallel Manipulators. Although parallel manipulators have been studied extensively, most of the studies have concentrated on the Stewart-Gough manipulator. The kinematic structures of parallel manipulators are enumerated according to their degrees of freedom and connectivity listing [22].. As shown in Figure 9.1, a parallel manipulator...
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Physical properties of metals, ceramics, and polymers, such as ductility, thermal expansion, heat capacity, elastic modulus, electrical conductivity, and dielectric and magnetic properties, are a direct result of the structure and bonding of the atoms and ions in the material. An understanding of the origin of the differences in these properties is of great engineering importance.. whereas in polycrystalline and...
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21, by permission of the publisher.. The atomic arrangement in crystals of the allotrophic forms of iron is shown in Fig. Austenite is a homogeneous phase, consisting of a solid solution of carbon in the y form of iron. The carbon content of a slowly cooled steel can be estimated from the relative amounts of pearlite and proeutectoid constituents in...
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Yet in the more than 100 years since that time, aluminum has become the second most widely used of the approximately 60 naturally occurring metals, behind only iron.. 3.2 PROPERTIES OF ALUMINUM. ALUMINUM ALLOYS 48 3.6 WORKINGSTRESSES 49 3.7 CHARACTERISTICS 51. Coloring 57 3.11.8 Hard Anodizing 57 3.11.9 Electroplating Applied Coatings 57 3.12 SUMMARY 57. 3 of aluminum weighs 0.1...
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Mechanical Properties of Copper Cold Rolled. Copper 59 4.1.2 Hardening Copper 60 4.1.3 Corrosion 60 4.1.4 Fabrication 60 4.2 SAND-CAST COPPER-BASE. Sb, max 0.003%. Bi, max 0.003%. A number of elements that reduce oxygen in copper, such as Zr, Cr, B, P, can also provide some softening resistance.. Manufacturers should be consulted in regard to its use under corrosive conditions.....
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Nickel, the 24th element in abundance, has an average content of 0.016% in the outer 10 miles of the earth's crust. Of the total known ore deposits, more than 80% is contained in laterite ores. Nickel has an atomic number of 28 and is one of the transition elements in the fourth series in the periodic table. Useful properties of...
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Titanium was first identified as a constituent of the earth's crust in the late 170Os. In the early 190Os, a sulfate purification process was developed to commercially obtain high- purity TiO 2 for the pigment industry, and titanium pigment became available in both the United States and Europe. In the 1920s, ductile titanium was prepared with an iodide dissociation method...
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Because of the widespread, easy availability of magnesium ores (e.g., from the ocean), the ore supply is, in human terms, inexhaustible.. some examples are the protection of buried pipelines and the prolon- gation of the life of household hot-water tanks. Magnesium in powder form is added to gray cast iron to produce ductile, or nodular, iron, an alloy that has...
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Plastics can be classified in several ways. Copolymer ABS 118 8.2.7 Poly vinyl Chloride 118 8.2.8 Poly(vinylidine chloride Poly(methyl Methacrylate Polyethylene Terephthalate) 119 8.3 ENGINEERING. THERMOPLASTICS 124 8.4.1 Poly(tetrafluoroethylene Poly(chlorotrifluoroethylene Fluorinated Ethylene-. They are prepared by the catalytic polymerization of ethylene. Their heat deflection temperatures are reasonable but not high. Some typical properties of PEs are listed in Table 8.1.....
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of Composite Materials 132 9.1.2 Comparative Properties of. MATRIX MATERIALS 136 9.2.1 Reinforcements 137 9.2.2 Matrix Materials 139 9.3 PROPERTIES OF COMPOSITE. MATERIALS 143 9.3.1 Mechanical Properties of. Composite Materials 144 9.3.2 Physical Properties of. 9.1.2 Comparative Properties of Composite Materials. There are a large and increasing number of materials that fall in each of the four types of composites,...