Table of Contents

Materials and Structure




Selection Issues

In a quest for light-strong structures, the density of a selected material will be another important parameter. In general, the lower the material density,
r, the more of it that can be used to perform a certain task if the system mass is fixed.

The quantities
(E/r), (E/r2), and (E/r3) are all employed in material selection for different tasks. The diagram shows a log-log plot of Young's modulus versus density for a wide range of materials. The yellow zone is metal alloys, the blue polymers, the green composite materials, and the brown woods. The red line represents a selected value of (E/r). All materials above the line have a higher value of this parameter, all below the line a lower value. If the selected value of (E/r) is related to a design criterion, those materials above the line exceed this criterion and merit further examination.

From: Ashby, Materials Selection, Pergamon (1993)