Calculate critical crack depth (the answer value must be correct (+15% error permitted) to get the mark) For a thick wall tube with a flaw of depth a under tensile hoop stress of a=690MPa due to the internal gas pressure P, what is the critical crack, depth "a" in mm ? In the answer cell put in a pure 3 sig. fig. number as your answer without units. The fracture toughness of the material is 68MPam1/2 For the crack geometry configuration known for this case, the stress intensity factor K is approximately expressed as K=1.70(a)1/2 Hint: for thick wall pressurized tubes, hoop stress (tensile stress in the wall) can be approximated as the gas/liquid pressure inside the tube. as an approximation, =P t is the wall thickness Calculate critical crack depth (the answer value must be correct (+15% error permitted) to get the mark) For a thick wall tube with a flaw of depth a under tensile hoop stress of a=690MPa due to the internal gas pressure P, what is the critical crack, depth "a" in mm ? In the answer cell put in a pure 3 sig. fig. number as your answer without units. The fracture toughness of the material is 68MPam1/2 For the crack geometry configuration known for this case, the stress intensity factor K is approximately expressed as K=1.70(a)1/2 Hint: for thick wall pressurized tubes, hoop stress (tensile stress in the wall) can be approximated as the gas/liquid pressure inside the tube. as an approximation, =P t is the wall thickness