中英文翻译--机械工程设计.doc

Mechanical engineering design 1. The meaning of design To design is to formulate a plan for the satisfaction of human need .in the beginning the particular need to the satisfied may be quite well-defined. Here are two examples of well-defined needs. 1. How can we obtain large quantities of power cleanly, safely, and economically without using fossil fuels and without damaging the surface of the earth? 2. This gear shaft is giving trouble; there have been eight failures in the last six weeks. Do something about it. On the other hand the particular need to be satisfied may be so nebulous and ill-defined that a considerable amount of thought and effort is necessary in order to state it clearly as a problem requiring a solution. Here are two examples. 1. Lots of people are killed in airplane accidents. 2. In big cities there are too many automobiles on the streets and highways. This second type of design situation is characterized by the fact that neither the need nor the problem to be solved has been identified. Note, too, that the situation may contain many problems. We can classify design too. For instance: 1. Clothing design 7. Bridge design 2. Interior design 8. Computer-aided design 3. Highway design 9. Heating system design 4. Landscape design 10. Machine design 5. Building design 11. Engineering design 6. Ship design 12. Process design In fact there are an endless number, since we can classify design according to the particular article or product or according to the professional field. In contrast to scientific or mathematical problems, design problems have no unique answers; it is absurd, for example, to request the “correct answer” to a design problem, because there is none. In fact a “good” answer today may well turn out to be a “poor” answer tomorrow, if there is a growth of knowledge during the period or if there are other structure or societal chan