Assume the internal pressure varies cyclically in the cylinder from pmin=0 to Pmax , where Pmax is 60% of the estimated maximum pressure that will lead to failure by yielding as predicted by Tresca criterion. The Paris law for the material is da = 1.6 X 10 "(AK) 9 m/cycle CA a. Find the number of cycles for the crack of initial length 200 = 0.01 m to grow to a length 20 = 0.025 m. b. Find the number of cycles before the crack reaches critical length (i. e life of the part).

Along 8-cm diameter steam pipe whose external surface temperature is 900c connects two buildings. the pipe is exposed to ambient air at 70c with a wind speed of 50 km/hr blowing across the pipe. determine the heat loss from the pipe per unit length. (b) air at 500c enters a section of a rectangular duct (15 cm x 20 cm) at an average velocity of 7 m/s. if the walls of the duct are maintained at 100c. a) the length of the tube for an exit temperature of the air to be 40 0c. b)the rate of heat transfer from the air. c) the fan power needed to overcome the pressure drop in this section of the duct.