Strength - Toughness

Strength and toughness are two properties that, as the terms are used in the non-scientific world.

Something that is strong must also be tough. They mean the same, right?

To a materials scientist, they most certainly do not. As the linked website defines, 'strength measures the resistance of a material to failure, given the applied stress (or load per unit area)' and 'toughness measures the energy required to crack a material; it is important for things which suffer impact.'

The interactive diagram (called Ashby diagrams) on the linked website graphs the strength vs toughness for a number of materials and finds them grouped with like materials (wood near wood, polymers near polymers, etc). The graph also has some java-based interactivity allowing each group to be further explored.

The site has a number of links at the bottom to similar pages exploring other materials relationships: young's modulus vs cost, strength vs cost, and a dozen more.

PS - Thanks to Todd for finding this site and to Caryn for passing it along.