第一组基张量由单位化的单位张量、单位化的偏应力（或弹性偏应变张量）以及一个正交于前两者的单位偏张量组成。
The first set consists of the normalized identity tensor and the normalized deviatoric stress tensor ( or deviatoric elastic strain tensor ) along with a unit deviatoric tensor orthogonal to both of them .
单位张量