Q2
It is found that the Main engine cylinder head studs are breaking during voyage:
(a) State, with reasons, the possible causes.
(6)
(b) State, with reasons and the likely effects on the engine if it is allowed to operate with broken studs.
(5)
(c) Explain how this problem can be minimized?
(5)
Reference Answer
### (a) Possible Causes for Cylinder Head Studs Breaking The failure of main engine cylinder head studs during a voyage is typically a result of fatigue failure, accelerated by one or more of the following underlying causes: 1. **Improper Tightening Procedure:** This is the most common cause. The goal of tightening is to create a specific preload (tension) in the stud, which provides the clamping force to seal the cylinder head against combustion pressures. * **Over-tightening:** Applying torque or hydraulic pressure beyond the manufacturer's specification stretches the stud past its elastic limit into the plastic region. This permanently weakens the stud, reduces its fatigue life, and makes it susceptible to failure under normal cyclic loading.
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