A thick-walled circular cylinder used as a barrel of a missile launcher is to be hydraulically treated by exerting an internal pressure which causes complete yielding of the wall thickness and when released leaves a residual tangential stress at the bore. The cylinder has an internal diameter of 400 mm, an external diameter of 800 mm, and it is made from anelastic/perfectly plastic material with a uniaxial yield stress of Y = 420 MPa. Determine: (1) (1) the internal pressure required for complete plastic deformation across the cylinder's wall thickness, and [3 marks] Where the given answer: The internal pressure for full plasticity is P,= 291 MPa assuming a safety factor f = 1 the tangential stress at the inner surface when the cylinder is fully plastic. [3 marks] Where the given answer: The tangential stress at the inner surface when the cylinder is fully plastic is 128.9 MPa 3 m Bi R=2m Figure Q4a A F = 2 kN