Consider a compact specimen that is loaded cyclically at a constant load amplitude with Pmax = 18 kN and Pmin = 5 kN. Using the fatigue crack growth data in Problem 5.1, calculate the number of cycles required to grow the crack from a/W = 0.35 to a/W = 0.60. Plot crack size vs. cumulative cycles for this range of a/W.

Apreheater involves the use of condensing steam at 100°c on the inside of a bank of tubes to heat air that enters at 1 atm and 25°c. the air moves at 5 m/s in cross flow over the tubes. each tube is 1 m long and has an outside diameter of 10 mm. what is the minimum value of nl needed to achieve an outlet temperature of t 75 c? what is the corresponding pressure drop across the tube bank?