In
continuum mechanics, the
Cauchy stress tensor ,
true stress tensor, or simply called the
stress tensor is a second order
tensor named after
Augustin-Louis Cauchy. The tensor consists of nine components that completely define the state of
stress at a point inside a material in the deformed state, placement, or configuration. The tensor relates a unit-length direction vector
n to the stress vector
T(n) across an imaginary surface perpendicular to
n:
where,