Strain -- from Eric Weisstein's World of Physics

The dimensionless parameter describing deformation. It can be thought of as the movement of one corner of a cubic box from its initial position under a stress:

where dl is the change in length and l is the original length. Materials often respond very differently depending on the rate at which straining occurs . For example, silly putty and the Earth's mantle act as elastic solids when the strain is applied rapidly, but deform like a fluid when the strain is applied slowly. In addition, if too large a stress is applied, these materials fail when their yield strength is exceeded.

Elasticity, Hooke's Law, Seismic Strain, Strain Rate, Strain Tensor, Strength, Stress

References