Elastic Stability

Abstract

In many design contexts, it is desirable to use components that have the minimum weight and cost compatible with acceptable values of strength and stiffness. The methods of the preceding chapters will often predict that the optimum design according to this criterion is a thin-walled structure. For example, we saw in §6.5 that closed sections are more effective at transmitting torques and that the strength and stiffness of such sections increases with the area enclosed by the section. It follows that the theoretical optimum torsion member for a given mass of material is a thinwalled cylindrical tube and the strength and stiffness theoretically increase without limit as the radius of the tube increases and the wall thickness correspondingly decreases [see equations (6.39, 6.40)]