Problem 4: One of the walls of a large fish tank made of polycarbonate panel with a plane strain fracture toughness of 2.2 MPa(m) 1/2 has a 0.05 mm deep surface scratch and is under a pressure of 15 MPa exerted by the water inside. a. (10 pts) Assuming creep is not a factor, will the fish tank break? Justify with your calculation. Assume Y = 2. b. (5 pts) If creep is a factor, will this tank do better with cold water or warm water, e.g., for tropical fish? Justify. Problem 5: A cylindrical rod of diameter 4.5 mm fabricated from a Ti-5Al-2.5Sn Ti alloy as a shaft of an industrial chemical propeller mixer is subjected to rotating-bending load cycling. Fatigue test results characterized as S-N curve are shown in Figure 8.21. The separation between load-bearing points is 130 mm. a. (10 pts) If the maximum load is 80 N, determine the minimum rod diameter to maintain a maximum stress of 250 MPa, well below the fatigue stress limit. b. (10 pts) If during service, there are particulate contaminants in the chemical mixture causing the maximum stress on the shaft to be 581 MPa, what would be the expected number of cycles to failure?