What factor is applied to carbon steel's flexure endurance limit to find its shear endurance limit____________?
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Answer: E. 0.75
Explanation
The shear endurance limit of carbon steel is derived by scaling its flexure endurance limit value. Empirical testing shows that torsional shear fatigue strength is lower than bending fatigue strength. Multiplying the flexure endurance limit by the standard empirical factor of 0.75 gives the shear limit. Endurance limits establish the threshold where materials withstand millions of repeated stress cycles safely. Flexural fatigue tests apply alternating bending moments to rotating or oscillating cantilever beam specimens. Torsional fatigue tests apply alternating twisting moments to determine corresponding shear endurance properties.
Machine design engineers use this conversion factor when designing shafts subjected to combined bending and torsion. Drive shafts and propeller shafts experience significant torsional shear stresses during continuous power transmission. Accurate fatigue limits prevent unexpected shaft failure in automotive and industrial power transmission systems. A factor of 0.25 is far too low and underestimates the actual torsional fatigue resistance of steel. A factor of 0.45 underestimates the empirical ratio typically observed between shear and flexural endurance limits. A factor of 0.55 is closer but still below the established carbon steel shear fatigue ratio.
- Subject
- Engineering
- Category
- Mechanical Engineering
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- —
- Difficulty
- medium
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