What happens when rope is bent around sheaves or a hook?

What happens when rope is bent around sheaves or a hook?

• A. Nominal strength is reduced
• B. Nominal strength is unchanged
• C. Nominal strength increases
• D. Rope fails immediately

Answer: (A)

When rope is bent around a sheave or a hook, the curvature places uneven stresses in the rope. The fibers on the inside of the bend get crushed and the fibers on the outside are pulled tighter, reducing the effective cross-sectional area that can carry load. This creates higher local stresses and wear, so the rope’s nominal strength in that bent configuration is lower than in a straight pull. The tighter the bend (smaller bend radius relative to rope diameter), the greater the reduction. It doesn’t increase strength, and it doesn’t automatically fail, but bending weakens the rope and can lead to failure if the bend is too sharp or repeated.

When rope is bent around a sheave or a hook, the curvature places uneven stresses in the rope. The fibers on the inside of the bend get crushed and the fibers on the outside are pulled tighter, reducing the effective cross-sectional area that can carry load. This creates higher local stresses and wear, so the rope’s nominal strength in that bent configuration is lower than in a straight pull. The tighter the bend (smaller bend radius relative to rope diameter), the greater the reduction. It doesn’t increase strength, and it doesn’t automatically fail, but bending weakens the rope and can lead to failure if the bend is too sharp or repeated.