- With reference to a vessel’s hull:
(a) explain the meaning of EACH of the following:
(i) dynamic stress;(3)
(ii) static stress;(3)
(b) state TWO examples of EACH type of stress explained in part (a).(4)
(a) Meaning of Each Term
(i) Dynamic Stress (3 marks)
- Dynamic stress is the fluctuating or varying stress imposed on the ship’s structure due to external forces that change with time or motion.
- These stresses are caused by the movement of the vessel in a seaway, such as pitching, rolling, slamming, or vibration.
- They result in cyclic loading, which can lead to fatigue in the hull structure and fittings over time.
(Definition + cause + effect = 3 marks)
(ii) Static Stress (3 marks)
- Static stress is the steady or unchanging stress produced by constant forces acting on the hull when the vessel is at rest or under uniform conditions.
- These forces include the weight of the ship, cargo, and equipment, balanced by the buoyant forces acting upward on the hull.
- The stress remains constant unless the ship’s loading or buoyancy distribution changes.
(Definition + cause + nature of load = 3 marks)