1. Pointed Impacts
A carbon-fiber tube can shrug off a baseball bat but will surrender to an axe. Sharp tips concentrate force into a pin-head area, slipping between the weave’s tows and slicing individual filaments. Once a micro-crack starts, the laminate unzips almost instantly. Guard tubes against dropped tools, metal edges, and flying debris; inspect surfaces after every shift.
2. Extreme Heat
Carbon fiber itself tolerates 3,000 °C, yet the surrounding epoxy or PEEK matrix softens far below that. When the resin melts—typically 120–350 °C depending on grade—the tube loses its “glue.” Layers separate, the profile sags, and strength vanishes. Always confirm the resin’s glass-transition temperature before placing tubes near engines, exhausts, or industrial ovens.
3. Sudden Cold Shocks
Rapid temperature swings (e.g., desert day to liquid-nitrogen night) can be just as brutal. The fiber and resin expand and contract at different rates, generating shear stresses that open micro-cracks. Over repeated cycles, these cracks coalesce and the tube snaps without warning. Specify toughened resins or allow slow thermal transitions when cycling extremes.
4. UV & Chemical Attack
Long-term sunlight degrades surface epoxy, creating chalky micro-cracks that act as stress risers. Chlorinated solvents, strong acids, or even certain hydraulic fluids can leach plasticizers and embrittle the matrix. Protect tubes with UV-blocking clear coats or chemical-resistant sleeves, and rinse spills immediately.
5. Hidden Internal Defects
Poor lay-up, trapped voids, or fiber waviness from the factory can lurk unseen. A tube that passes visual checks may still fail under moderate load if the defect is in the load path. Specify ultrasonic or CT scanning for critical parts, and retire any tube that has taken a hard knock—even if it looks fine.
