Exam Question
(a) Explain fatigue cracking, stating its causes and propagation. (8)
(b) Explain, how poor maintenance and engine overload may contribute to the risk of fatigue cracking of cylinder head holding studs. (8)
Class 2 (2nd Engineer)
MEKM
📅 Jun 2025
Reference Answer
### (a) Fatigue Cracking: Causes and Propagation
**Concept of Fatigue**
Fatigue is a failure mechanism that occurs in a material subjected to repeated, fluctuating, or cyclic stresses. The failure can occur at a stress level significantly lower than the material's Ultimate Tensile Strength (UTS) or even its yield strength. It is a progressive and localized form of structural damage that initiates as a microscopic crack and propagates until the component fails. It is the most common cause of failure in dynamic machinery components.
**Causes of Fatigue Cracking**
**Concept of Fatigue**
Fatigue is a failure mechanism that occurs in a material subjected to repeated, fluctuating, or cyclic stresses. The failure can occur at a stress level significantly lower than the material's Ultimate Tensile Strength (UTS) or even its yield strength. It is a progressive and localized form of structural damage that initiates as a microscopic crack and propagates until the component fails. It is the most common cause of failure in dynamic machinery components.
**Causes of Fatigue Cracking**
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