A spherical steel pressure vessel (diameter 500 mm, thickness 10 mm) is coated with brittle lacquer that cracks when the strain reaches 150 x 10⁻⁶.
a. What internal pressure p will cause the lacquer to develop cracks?
(Assume E 205 GPa and v 0.3) .
b. If the strain is measured at 125 x 10⁻⁶%, what is the internal pressure at that point?