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Q1. A compound shaft consists of two sections of the same material arranged in series and is required to transmit 16kW at 80 rev/min. Section A is solid of outside diameter 60mm and length 120mm. Section B is hollow with a concentric hole 70% of the outside diameter. The angle of twist is to be the same for each section. The torsional stress in section A is 150% of that in section B.

Calculate EACH of the following:

(a) the outside diameter of section B of the shaft;

(b) the length of section B;

(c) the maximum shear stress in both sections of the shaft.

Q2. A steel rod is 280mm long with a diameter of 28mm. It is firmly attached at one end to a copper rod of length 580mm. When the combined assembly is subjected to a tensile pull of 40kN, the extensions of the steel and copper portions are found to be equal. Calculate EACH of the following:

(a) the diameter of the copper rod;

(b) the stress in each rod;

(c) the total extension;

(d) the work done in straining the assembly.

Note: Modulus of Elasticity for Steel = 210 GN/m²

Modulus of Elasticity for Copper = 90 GN/m²

Q1. In a four-ram hydraulic steering gear the centre line of the rams is 0.9m from the centreline

of the rudder stock. The diameter of the rams is 280mm and the diameter of the rudder stock is 390mm. When in the mid-ships position, the rudder is struck by a heavy sea which causes the relief

valves of the ram cylinders to operate. The relief valves are set to operate at 4MN/m².

Calculate EACH of the following:

(a) the maximum shearing stress imposed on the rudder stock;

(b) the percentage increase in shearing stress imposed on the rudder stock if the relief valves are set at 4.2 MN/m².