Σ
w = 20 N/mm
2 dw = 4mm t = 8 mm
σc = Initial compressive stress in cylinder
=

= 7.854 N/mm2 (comp. )
Say internal pressure = P
Axial stress, σ
a′ =

= 6.25 P
Hoop stress = σc′
σCR = (σc′ − 7.854) = 6.25 P, (as given) ⋯ ①
or σc′ = 6.25 P + 7.854 ⋯ ②
Using equilibrium and compatibility conditions
Pd = 2tσc′ +

From equation ④
σ
c′ − ν
cσ′
c = σ′
w ×

or 6.25 P + 7.854 − 0.35 (6.25 P) = 0.5 σw′
or 4.0625 P + 7.854 = 0.5 σw′
σw′ = 8.125 P + 15.708
Putting the values σw′ and σc′ in equation ③
P × 200 = 2 × 8 × (6.25p + 7.854) +

× (8.125p + 15.708)
200P = 100P + 125.664 + 6.283(8.125p + 15.708)
100P = 125.664 + 51.05P + 98.69
48.95 P = 224.354
P = 4.58 N/mm2