finite deformation

Finite deformation in mechanics refers to situations where the extension and rotation of line elements are unrestricted in size. This is in contrast to small-strain theory, which is appropriate when these changes are very small.12

In continuum or solid mechanics, problems are addressed by considering:
1. Newtonian equations of motion: These express conservation of momentum and the concept of stress.12
2. Geometry of deformation: This involves expressing strains in terms of displacement gradients.12
3. Material properties: These are the relations between stress and strain, characteristic of the specific material.12

Ductility, the capacity of a material to deform permanently under stress, is a key property. Materials with high ductility, like most steels, can accommodate stress concentrations, unlike brittle materials such as glass, which fracture easily.3