We study an arbitrary deformation of a configuration of a body and show
that this deformation may be reduced to a sequence of two special deformations: the
rotation and stretching. The kinematics of a deformation is also considered. We
introduce a notion of a vorticity vector and discuss its relationship with the
antisymmetric part of the velocity gradient.
Keywords: Deformation, Deformation gradient, Deformation rate tensor,
Kinematics of a deformation, Polar decomposition theorem, Rotation tensor,
Stretching tensor, Velocity gradient, Vorticity vector.
