In a thick cylinder subjected to internal and external pressures let $r_{1}$ and $r_{2}$ be the internal and external radii respectively. Let u be the radial displacemet of a material element at radius $r_{1}$,$r_{2}$$\geq$$r\geq r_{1}$. Identifying the cylinder axis as z axis the radial strain component $e_{rr}$ is (IES-96)
