TABLE OF CONTENTS 
Material properties limit performance. We need a way of surveying them, to get a feel for the values design-limiting properties can have. One property can be displayed as a ranked list or bar-chart. But it is seldom that the performance of a component depends on just one property. Almost always it is a combination of properties that matter: one thinks, for instance, of the strength-to-weight ratio, ? f/ ?, or the stiffness-to-weight ratio, E/ ?, that enter light-weight design. This suggests the idea of plotting one property against another, mapping out the fields in property-space occupied by each material class, and the sub-fields occupied by individual materials.
The resulting charts are helpful in many ways. They condense a large body of information into a compact but accessible form; they reveal correlations between material properties that aid in checking and estimating data; and in later chapters they become tools for tackling real design problems.
The idea of a materials-selection chart is described briefly in Section 4.2. Section 4.3 is not so brief: it introduces the charts themselves. There is no need to read it all, but it is helpful to persist far enough to be able to read and interpret the charts fluently, and to understand the meaning of the design guidelines that appear on them. If, later, you use one chart, you should read the background to it, given here, to be sure of interpreting it correctly.
As explained in the preface, you...
