question_answer

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 displacement of a material element at radius \[r,{{r}_{2}}\ge {{r}_{1}}.\] Identifying the cylinder axis as z axis, the radial strain component \[{{\varepsilon }_{r}}\] is:

A) \[u/r\]                           

B) \[u/\theta \]

C) \[du/dr\]            

D) \[du/d\theta \]