Calculate the final critical surface crack length if the fatigue life of a material with a Kic of 25 Mpa m1/2 must be a minimum of 6.6 x 105 cycles. Assume the initial maximum edge surface crack to be 1.1 mm and the maximum tensile stress of 137MPa. Assume m=1.3, and A = 7.5x10-13 and Y = 1.19. The answer should be in mm with 2 decimals of accuracy.

Amixture of slurry and mud is to be pumped through a horizontal pipe of diameter 500 mm. the fluid behaves as a bingham plastic with a yield stress of 30 pa and viscosity 0.04 pa.s. describe the effects of the shear stress through a transverse section of the pipe by plotting the variation in shear stress and velocity profile: (i) just before the slurry starts to move (ii) as the slurry flows when the pressure gradient is double that in part (i)