When examining a heavy close-coiled helical spring, the shear stress experienced at the inner wire face compared to the outer face is_________________?
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Answer: A. larger
Explanation
Close coiled helical springs experience higher torsional shear stress at the inner wire face. Direct shear stress combines with curvature effects to concentrate stresses on the inside diameter. The inner radius of the spring wire undergoes more severe stretching during coiling and loading. Helical springs twist primarily in torsion when subjected to axial compressive or tensile loads. Wahl factor equations account for both direct shear and coil curvature stress concentrations. Wire cross sections experience uneven stress distributions across their inner and outer boundaries.
Spring designers use the inner fiber stress values to prevent permanent yielding during operation. High performance suspension springs must be engineered to withstand these elevated inner face stresses. Failing to account for curvature stress leads to premature fatigue failure in heavy industrial springs. Shear stress is never equal across the wire because geometry creates inherent inner face concentration. The inner stress is consistently larger and does not flip unpredictably based solely on coil diameter. Standard mechanics of materials confirm that inner fiber stresses always exceed outer face levels.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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