A metal tube of 50-mm bore and a wall thickness of 1.5 mm is closely wound externally by a steel wire 1.0 mm diameter. Determine the tension under which the wire must be wound on the tube if an internal pressure of 1.8 N/mm2 is required before the tube is subjected to tensile stress in the circumferential direction. For metal E = 105 GPa and n = 0.34 and for E = 210GPa.
Let us first determine the stresses σ'a, σ'c and σ'w developed in cylinder and the wire due to the internal pressure.
Take the unit length of cylinder, l = 1mm
