In science courses we learn to compute the behavior of nature in a series of established experiments and phenomena. In engineering courses we learn to compute currents and voltages in amplifiers and motors, forces and power in linkages and engines, reaction rates in chemical systems, earth transfer in road building, and the like. This is good educational policy; learning applied mathematics is difficult for most of us and is best done in the disciplined operation of a school rather than left to be picked up on the job.
The ability to compute separates the engineer from the technician. An education in engineering mathematics generates an insight (i.e., an intuitive understanding) into the behavior of physical things which cannot be attained in any other way and which is essential for inventive thinking, that is, the generation of new qualitative ideas which will work. If you have really learned what calculus means, you have a gut feel for the behavior of billiard balls, automobiles, electric currents, servomechanisms, space vehicles, and all the other objects of engineering which no amount of practical experience alone can provide. On the other hand, quantitative design can be used only on an engineering object which originated as a qualitative idea.
To be successful, engineers need a large body of knowledge and skills that is not subject to mathematical computation; this body of knowledge and skills is the subject of this book. It deals with a variety of non-quantitative design information, ideas, and techniques which will help you to devise new and advanced engineering objects in your field.
Real-World Design Process
This process iterates around three elements:
- Qualitative design. The generation of ideas, structures, concepts, combinations, configurations, and patterns. The results are expressed in sketches, layouts, schematics, and diagrams.
- Quantitative design. The computation of the magnitude of the elements in a qualitative design. The results are expressed in numbers, usually with physical units (e.g., length, voltage, temperature).
- Experimental design. The use of physical models and tests to compensate for both qualitative and quantitative uncertainty.
Quantitative understanding, not just passing examinations, of science and mathematics gives you insight into the behavior of nature (including your own qualitative ideas) and helps you to generate workable qualitative designs.
Qualitative design is sometimes called synthesis; quantitative design is sometimes called analysis.
Uses and Limits of the Computer in Design
The computer is the greatest tool ever developed for computational engineering and, perhaps, for design drafting. Efforts are under way by academic theoreticians, under the names of expert systems and artificial intelligence, to computerize qualitative design. This deals with your use of insight, judgment, persuasion, will, prediction of human behavior, and ingenuity and with a number of principles of design to produce qualitative designs and get them used. Perhaps these capabilities and activities will be reduced to computer programs someday, but this design practitioner is not holding his breath.
Role of Human Judgment
The role of human judgment in design appears in predicting the acceptability of the design to other people and in predicting the performance of the design long before it is reduced to mathematical computation. For any problem there are many bad designs possible and only a few good ones. Human judgment is the first filter in selecting the good ones.
