ME or MEng Master of Engineering Master of Engineering Machine Design 4

Question 1

In a clutch or brake design, the uniform pressure assumption is preferred over the uniform wear assumption when:

Accepted Answer

The friction surface is new and unworn

Answer

Uniform pressure applies to new surfaces before wear occurs; after break-in, uniform wear (p·r = constant) governs.

Question 2

The Lewis form factor Y in gear bending stress analysis accounts for:

Accepted Answer

Tooth geometry and the parabolic beam analogy

Answer

The Lewis form factor Y reflects the shape of the gear tooth, derived from treating it as a cantilever beam with a parabolic fillet.

Question 3

A shaft supported by two bearings carries a concentrated load of 2 kN at mid-span of 600 mm length. The maximum bending moment is:

Accepted Answer

300 N·m

Answer

For a simply supported beam with center load: M_max = PL/4 = 2000×0.6/4 = 300 N·m.

Question 4

Fretting fatigue in machine components is most effectively prevented by:

Accepted Answer

Applying compressive residual stress via shot peening

Answer

Shot peening introduces compressive residual stresses that close fretting cracks and significantly improve fatigue life.

Question 5

In a V-belt drive, the angle of wrap on the smaller sheave is reduced compared to a flat belt because:

Accepted Answer

The sheave groove increases effective friction, needing less wrap

Answer

The wedging action in the V-groove amplifies friction, so V-belts can transmit the same power with smaller wrap angles.

ME or MEng Master of Engineering Practice Test