Critical factors affecting the strength of climbing ropes: A study of wear, fatigue loading and temperature

• Cyclic mechanical loading has no negative influence on the degradation of the rope • Wear and elevated temperature considerably reduce the load-bearing capacity of the rope • Severe wear of the rope sheath reduces the strength of the rope by up to 16.7 % • Elevated temperature (8h@100°C) reduces the strength of the rope by up to 24.3 % • Results confirm the usefulness of visual inspection as a retirement protocol of the rope • Abseiling method could be adapted to extend the service life of the rope Climbing ropes are critical safety equipment, yet there is little data on how various stress factors affect their load-bearing capacity over time. This study investigates the individual and combined effects of wear, cyclic loading and elevated temperature on the quasi-static strength of dynamic 9.8 mm kernmantle ropes. Wear was introduced through a reproducible mechanical abrasion process; dynamic fatigue was simulated with 300 cyclic tensile loads of 15 kN; and temperature effects were investigated by exposing the ropes to 100°C for up to 8 hours. The results revealed that: i) severe sheath wear led to an average reduction in rope strength of 16.7 %, with the sheath losing 56.8 % and the core 1.8 % of its strength; ii) an 8-hour heat load at 100°C reduced the load-bearing capacity of the rope by an average of 24.3 %, with the sheath losing 22.3 % and the core 14 % of its strength; iii) surprisingly, cyclic fatigue loading improved the static load-bearing capacity by an average of 5.5 %, possibly due to an internal rearrangement of the rope strands enhancing structural support; iv) the combined effect of wear and temperature was less than additive: maximum wear plus 8 hours of heat exposure reduced the strength to 73.9% of the original value, compared to the predicted combined decrease of 59% if the effects were additive. These results provide critical insights into rope degradation mechanisms and demonstrate that combined stress factors interact in complex, non-linear ways.