连杆机构英文文献和中文翻译

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Construction equipment such as tractors, cranes, and backhoes all use linkages ex- tensively in their design. Figure 1-1b shows a small backhoe that is a linkage driven by hydraulic cylinders. Another application using linkages is thatof exercise equipment as shown in Figure I-Ie. The examples in Figure 1-1 are all of consumer goods which you may encounter in your daily travels. Many other kinematic examples occur in the realm of producer goods-machines used to make the many consumer products that we use. You are less likely to encounter these outside of a factory environment. Once you be- come familiar with the terms and principles of kinematics, you will no longer be able to look at any machine or product without seeing its kinematic aspects.70588

1.5 THE DESIGN PROCESS Design, Invention, Creativity

These are all familiar terms but may mean different things to different people. These terms can encompass a wide range of activities from styling the newest look in clothing, to creating impressive architecture, to engineering a machine for the manufacture of fa- cial tissues. Engineering design, which we are concerned with here, embodies all three of these activities as well as many others. The word design is derived from the Latin designare, which means "to designate, or mark out." Webster's gives several defini- tions, the most applicable being "to outline, plot, or plan, as action or work ... to con- ceive, invent- contrive." Engineering design has been defined as " ... the process ofap- plying the various techniques and scientific principles for the purpose of defining a de- vice, a process or a system in sufficient detail to permit its realization ... Design may be simple or enormously complex, easy or difficult, mathematical or nonmathematical; it may involve a trivial problem or one of great importance." Design is a universal con- stituent of engineering practice. But the complexity of engineering subjects usually re-

DESIGN OF MACHINERY CHAPTER 1

quires that the student be served with a collection of structured, set-piece problems designed to elucidate a particular concept or concepts related to the particular topic. These textbook problems typically take the form of "given A, B, C, and D, find E." Un- fortunately, real-life engineering problems are almost never so structured. Real design problems more often take the form of "What we need is aframus to stuff this widget into that hole within the time allocated to the transfer of this other gizmo." The new engi- neering graduate will search in vain among his or her textbooks for much guidance to solve such a problem. This unstructured