Connecting rod bolts are initially tightened with a tension exceeding the external working load so that___________________?
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Answer: C. the resultant load on the bolt would not be affected by the external cyclic load
Explanation
Connecting rod bolts experience heavy cyclic tensile loads during every engine operating cycle. Applying a high initial preload clamps the joint tightly so that external working loads do not separate the faces. This high preload ensures the bolt experiences only a tiny fraction of the external cyclic load fluctuation. Bolt preloading creates an initial tensile stress that stretches the bolt and compresses the joined metal components. Joint stiffness relative to bolt stiffness determines how much external load fluctuation is transmitted to the bolt. Minimizing load amplitude variations protects high-strength fasteners from progressive fatigue failure over time.
Preventing joint opening is a benefit, but the primary mechanical reason is insulating the bolt from cyclic load swings. Making bolts the weakest element is undesirable because fasteners should never be designed to fail first. Preventing loosening is addressed by locking mechanisms rather than the high preload method used to manage fatigue.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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