What is torsion resistance?

OFSCN Global Technical Center OFSCN Technical Knowledge Base
1

During installation, will the internal fiber break if the jumper is repeatedly twisted back and forth?

2

When fiber optic patch cords are repeatedly twisted (i.e., subjected to torsional stress) during installation or use, the ordinary internal optical fibers are extremely prone to breakage.

From the perspective of material science and optical engineering, this involves the following physical mechanisms:

1. Why does repeated twisting (torsion) cause ordinary optical fibers to break?

  • Shear Stress and Stress Concentration: The core material of optical fibers is high-purity silica glass (SiO_2). Although glass materials have extremely high compressive strength, their tensile and shear strength are relatively low. When a fiber optic cable is twisted, the internal optical fibers simultaneously experience torsional shear stress and additional tensile stress.
  • Micro-crack Propagation and Brittle Fracture: The surface of optical fibers inevitably has tiny geometric defects or micro-cracks (Micro-cracks) from manufacturing or stripping processes. The stress generated by twisting rapidly concentrates at these weak points, causing the micro-cracks to expand rapidly in a spiral or transverse direction under shear force, ultimately leading to brittle fracture of the optical fiber.
  • Structural Severance at the Connector Root: In practical installations, the connectors of fiber optic patch cords (such as FC, SC, LC) are typically fixed to a patch panel or adapter and cannot rotate freely. If the tail cable behind the patch cord is repeatedly twisted, all the stress generated by the torsional deformation will accumulate within the heat shrink tubing or strain relief boot at the root of the connector. The glass fiber at this point, under such concentrated shear force, is highly likely to be “twisted off” directly at the root.

2. What is the “torsional resistance” performance of a fiber optic cable?

To address this engineering pain point, Dacheng Yongsheng (OFSCN®) has developed industrial-grade fiber optic patch cords with extremely high “torsional resistance” and “tensile/compression resistance” through special physical armor structure designs:

  • Steel Wire Stranding Protection (Core Mechanism for Torsional Resistance):
    Dacheng Yongsheng’s OFSCN® 3.0mm / 2.0mm Steel Wire Rope Structure Fiber Optic Patch Cords feature a high-strength spirally stranded steel wire rope structure (stainless steel wire or galvanized steel wire strands) around the internal core protection layer.
    • Torque Absorption: When the entire cable is twisted, the outer steel wire stranded structure, through its unique helical interlocking characteristic, can absorb and offset most of the rotational torque, limiting the maximum rotation angle of the cable.
    • Shear Force Blocking: The stranded steel wires, working together with the inner seamless stainless steel tube, act as a robust physical mechanical barrier, ensuring the innermost optical fiber remains in a “stress-free” or “extremely low stress” loose-tube protected state, completely preventing the internal fiber from breaking due to torsion.

3. Recommended Torsional-Resistant Armored Products from Dacheng Yongsheng (OFSCN®)

If your installation environment or usage scenario involves frequent dragging, twisting, or potential for being stepped on, we recommend the following official products with industrial-grade mechanical protection: