I - Answer to part (a) should be no more than about 250 words long. Show clearly each stage of your working for part (b).
a. By considering a cylindrical pressure vessel subjected to an internal pressure P, show in which one of the three primary stress orientations a crack-like defect would be most likely to cause failure when the internal pressure reaches a critical value. Support your answer with sketches and explain your reasoning.
b. A cylindrical pressure vessel that is used for chemical processing is routinely pressurized to 26 MN m-2. The vessel has a mean diameter of 1.6 m and a wall thickness of 0.095 m, and is constructed from welded plates of material with a UTS of 565 MN m-2 and a yield strength of 460 MN m-2.
i. Calculate the maximum stress at full pressure that could drive the growth of a crack.
ii. State, with justification, whether or not the service condition represents a high load on the structure.
iii. To determine the safety of the vessel, you need to know the fracture toughness of the steel. Suggest how you could obtain this value.
II - Answer to part (a) and (b) should be no more than about 350 words long. Show clearly each stage of your working for part (c).
By referring to the photograph of a rower in Figure 1 and the schematic of the arrangement in Figure 2, complete the following.
a. Give examples of different parts of the rower's body displaying.
i. rectilinear motion
ii. circular motion
iii. curvilinear motion
Illustrate your answer with diagrams.
b. Identify which parts of the rower's body could be modelled as a piston and crank mechanism and illustrate the mechanism with a diagram.
c. Assuming that the thigh and calf (t and c in the schematic) have an equal length of 0.6 m and the angle q that they make is 45°to the horizontal. Estimate the average speed the seat would slide during one full stroke (i.e. power and recovery) when rowing at 27 strokes/min; given that the travel of the seat in each direction can be modelled as: travel of seat = t + c - r1 - r2.