Torsion vs. Bending: Different Cable Engineering Requirements
A fundamental distinction in cable engineering is understanding the difference between bending and torsion stress .
Bending Stress:
Cable flexes in one plane
Stress distributed across cross-section (tension outside, compression inside)
Strand exchange through cabling evens out stress
Measured by bending radius and bending cycles
Torsion Stress:
Cable rotates around its own axis
Shear stress around cable axis
Conductors forced into spiral motion around center
Distance from center determines stress level (outer conductors experience more strain)
Measured by torsion angle per meter and torsion cycles
Key Implication: A cable optimized for bending cannot be used for torsion. The cabling direction, lay length, fillers, and jacket design are fundamentally different. Torsion cables require spiral cabling arrangements, central anti-torque elements, and slip layers that allow conductors to move freely .
