where the stress tensor is symmetric such that
When using cylindrical polar coordinates (r,θ,z) such that
the equilibrium equations (2.120)–(2.122) are written as
where the stress tensor is symmetric such that
When using spherical polar coordinates (r,θ,ϕ) such that
the equilibrium equations (2.120)–(2.122) are written as
where the stress tensor is symmetric such that
2.13 Strain–Displacement Relations
For the special case when the strain tensor εij is uniform, and on using (2.107), the displacement fields
and
both lead to the same strain field given by