고체역학 (Beer) — Transformations of Stress and Strain: Problem 7.101

7.101 A spherical pressure vessel of 1.2-m outer diameter is to be fabricated from a steel having an ultimate stress \(\sigma_U = 450 \text{ MPa}\). Knowing that a factor of safety of 4.0 is desired and that the gage pressure can reach 3 MPa, determine the smallest wall thickness that should be used.