It can be shown that it is possible to find a coordinate system ( n 1 , n 2 , n 3 ) in which the components of the strain tensor are ε ε _ _ _ _ = [ ε ε 1 0 0 0 ε ε 2 0 0 0 ε ε 3 ] ⟹ ⟹ ε ε = ε ε 1 n 1 ⊗ ⊗ n 1 + ε ε 2 n 2 ⊗ ⊗ n 2 + ε ε 3 n 3 ⊗ ⊗ n 3 The components of the strain tensor in the ( n 1 , n 2 , n 3 ) coordinate system are called the principal strains and the directions n i are called the directions of principal strain. Since there are no shear strain components in this coordinate system, the principal strains represent the maximum and minimum stretches of an elemental volume.