The endurance limit of a machine component having a polished finish versus one with a rough surface is_________________?
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Answer: A. more
Explanation
A polished surface finish removes microscopic machining marks that act as severe stress risers. Eliminating surface notches prevents crack initiation sites under repeated cyclic loading conditions. Consequently, the endurance limit of a polished machine component is higher than a rough one. Surface roughness creates microscopic valleys where stress concentrates during cyclic loading. Endurance limit measures the maximum alternating stress a material can withstand indefinitely. Mechanical polishing and buffing improve surface integrity and extend fatigue lifespan.
Automotive crankshafts and aircraft turbine blades undergo fine polishing to maximize fatigue life. High-stress rotating machinery components require smooth surface finishes to prevent premature failure. Manufacturing quality control standards specify maximum allowable surface roughness parameters. Saying the endurance limit is less for a polished finish contradicts fundamental fracture mechanics. Rough surfaces always exhibit lower fatigue limits due to stress concentration notch effects. The endurance limit depends directly on surface finish quality, ruling out unpredictable results.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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