Cylindrical pressure vessels with a radius of 1.0 m are made of aluminum alloy (KIc= 24 MPa√m, σY= 900 MPa). Semi-circular cracks of length 2a, and depth a, may exist in the wall of the cylinder. For these cracks, the stress-intensity factor is given by €KI=σπa, where σis the stressnormal to the crack. These vessels were initially designed to work under constant internal pressure of P= 1.0 MPa, with a 2.0 safety factor on thickness for the leak-before-break consideration. However, due to some emergency these vessels need to be used to support an oscillating axial loadthat varies between 0kN and +3400 kN for at least 10,000 cycles. The Paris law is given by94/1.510() m/cycleIda dNK−=×Δ, where ΔΚIis in MPa. m1/2. To achieve this goal, you plan to do a pressure proof test first. What is the value of such proof-testing pressure? (9.3 MPa)