Question A4: A thin-walled cylindrical pressure vessel is constructed using an alloy for which Kc=50MPaVm and y=1000MPa. The pressure vessel has a diameter d=2r=3m and wall thickness, t, of 30mm and is known to have thumb-nail cracks of depth 10mm oriented perpendicular to the hoop stress direction. The vessel is subjected to an increasing internal pressure for which the hoop stress is given by =tpr. The stress intensity factor for the thumb-nail cracks is given by K=1.26a (where a is the crack depth). (a) How will the pressure vessel fail? Please provide necessary solution steps. [5 marks] (b) The vessel is to be used for storing liquid ammonia at 20C and 10 Bar. Please discuss safe design considerations, if the geometries of the pressure vessel (diameter, wall thickness) are fixed. [5 marks]