# Creative Design H. K. D. H. Bhadeshia

The teaching of design in materials science generally takes the form of Galileo's square-cube law. The weight of a structure increases with the cube of its dimensions, but the area of the load bearing sections increases only with the square of the dimensions. Consequently, an elementary structure which is scaled upwards may eventually fail under its own weight. Modern versions of this kind of teaching involve the quantitative analysis of measurable material variables such as the yield strength and the Young's modulus. Thus, the best material to design a leaf spring to tolerate a given deflection without yielding would be one which has the highest ratio of (yield/modulus).

A materials scientist must understand the methodology behind the derivation of these square-cube type laws. In elementary cases, he may even be required to know the actual equations. However, in most cases, it is likely that the scientist can consult an engineer for help with the quantitative rule, or may be able to access computer programs for such calculations. It is easy to imagine some menu driven materials selection program with facilities for yield, deflection, weight etc. controlled design, and even combinations of design criteria.

There are many cases in science and in enterprise, where it is not technological design, but creative design which leads to significant wealth creation. A perfect example is the Sony Walkman. It is not the technology of the tape recorder which led to an immense increase in its sales, but rather, an artful manipulation of format.

There have been a number of detailed studies and recommendations about the teaching and practice of design in the engineering profession. The general principles are therefore well researched. Creative design nevertheless remains very difficult to teach, primarily because the principles are abstract whereas applications develop more rapidly from examples. Most of the design exercises in our subject tend to focus on materials selection, which is a means to an end (i.e., a tool) more than something which leads to an invigorating outcome. Woody Flowers of the Massachusetts Institute of Technology has developed methods which have been proven to inspire engineering undergraduates, so much so, that his scheme has now been internationally applied. This article contains suggestions for adapting some of his ideas for materials science. It begins with a general discussion of design in the context of materials. The discussion is then illustrated with two complete examples, which can in principle be incorporated without modification into any materials science course.