 It is used widely in numerical algorithms in metal plasticity (where there
is no change in volume during plastic deformation).It can be called "weighted Cauchy stress tensor" as well.The nominal stress formula_26 is the transpose of the first Piola-Kirchhoff stress (PK1 stress, also called engineering stress) formula_3 and is defined via
or
This stress is unsymmetric and is a two-point tensor like the deformation gradient.