Prototypes are often very expensive but may be the most economical way to prove a design, short of building the actual, full-scale device. Prototypes can take many forms, from working scale models to full-size, but simplified, representations of the concept. Scale models introduce their own complications in re- gard to proper scaling of the physical parameters. For example, volume of material var- ies as the cube of linear dimensions, but surface area varies as the square. Heat transfer to the environment may be proportional to surface area, while heat generation may be proportional to volume. So linear scaling of a system, either up or down, may lead to behavior different from that of the full-scale system. One must exercise caution in scal- ing physical models. You will find as you begin to design linkage mechanisms that a simple cardboard model of your chosen link lengths, coupled together with thumbtacks for pivots, will tell you a great deal about the quality and character of the mechanism's motions. You should get into the habit of making such simple articulated models for all your linkage designs.
TESTING of the model or prototype may range from simply actuating it and ob- serving its function to attaching extensive instrumentation to accurately measure dis- placements, velocities, accelerations, forces, temperatures, and other parameters. Tests may need to be done under controlled environmental conditions such as high or low tem- perature or humidity. The microcomputer has made it possible to measure many phe- nomena more accurately and inexpensively than could be done before.
Production
Finally, with enough time, money, and perseverance, the design will be ready for pro- duction. This might consist of the manufacture of a single final version of the design, but more likely will mean making thousands or even millions of your widget. The dan- ger, expense, and embarrassment of finding flaws in your design after making large quantities of defective devices should inspire you to use the greatest care in the earlier steps of the design process to ensure that it is properly engineered.
The design process is widely used in engineering. Engineering is usually defined in terms of what an engineer does, but engineering can also be defined in terms of how the engineer does what he or she does. Engineering is as much a method, an approach, a process, a state of mind for problem solving, as it is an activity. The engineering ap- proach is that of thoroughness, attention to detail, and consideration of all the possibili- ties. While it may seem a contradiction in terms to emphasize "attention to detail" while extolling the virtues of open-minded, freewheeling, creative thinking, it is not. The two activities are not only compatible, they are symbiotic. It ultimately does no good to have creative, original ideas if you do not, or cannot, carry out the execution of those ideas and "reduce them to practice." To do this you must discipline yourself to suffer the nitty-gritty, nettlesome, tiresome details which are so necessary to the completion of any one phase of the creative design process. For example, to do a creditable job in the de- sign of anything, you must completely define the problem. If you leave out some detail of the problem definition, you will end up solving the wrong problem. Likewise, you must thoroughly research the background information relevant to the problem. You must exhaustively pursue conceptual potential solutions to your problem. You must then ex- tensively analyze these concepts for validity. And, finally, you must detail your chosen design down to the last nut and bolt to be confident it will work. If you wish to be a good designer and engineer, you must discipline yourself to do things thoroughly and in a log- ical, orderly manner, even while thinking great creative thoughts and iterating to a solu- tion. Both attributes, creativity and attention to detail, are necessary for success in engi- neering design. 连杆机构英文文献和中文翻译(8):http://www.751com.cn/fanyi/lunwen_79963.html