Is toughness a better metaphor than resilience?

Abstract

Toughness is arguably a better metaphor than resilience to describe the characteristics of wider systems for which the term ‘resilience’ is currently employed. This argument is presented by describing the various features of a stress–strain curve, to which the two terms relate. In particular, it is the large energy-absorbing and strain capacities of the plastic region that make toughness a more apt metaphor. System toughness can be seen as having three aspects, namely robustness, redundancy and element toughness. Similarities are demonstrated between the analogical source of structural mechanics and two analogical targets, namely transportation and social systems. ‘Post-yield’ behaviour in such wider systems can be classified as to whether they are ductile or brittle; and as to whether they display strain hardening or strain softening.