5) A cylindrical steel pressure vessel of 7.5m diameter and 40mm wall thickness is to operate at a working pressure of 5MPa. The design assumes that small cracks may be present that will gradually extend due to fatigue. a) If the fracture toughness of the steel is 200MN3/2, would you expect the vessel to fail by leaking; or by fast fracture? [6\%] The growth of a crack may be represented by the equation dNda=A(K)4 Where da/dN is the extent of crack growth per loading cycle and K is the stress intensity factor for the crack