Materials Engineering Department
BS in Materials Engineering
When climbing rope is used outdoors, it is exposed to foreign particles such as sand and silt. These particles can potentially work their way through a rope’s sheath and damage the load bearing core decreasing the rope’s strength without exhibiting obvious wear. This project quantified the effect of abrasive particles on the fatigue life of nylon climbing rope. The experimental design involved 18 pieces of static nylon rope of kernmantle construction. 9 of these samples were heavy agitated in a slurry of water, silt, sand and soil, and left to sit for 24 hours. The remaining 9 samples were submerged in clean water for the same period. Two sections of rope from each the dirty and clean groups were fatigued at 100, 200, 300, 400 cycles and one section each at 500 cycles. After fatigue treatment, the rope was tensile tested. Comparisons were made between the strengths of the dirty rope samples and the clean rope samples. It was found that exposure to abrasive particles decreases the fatigue life of the rope. It should be noted that the clean and dirty rope segments had identical strengths before fatigue treatment (5500lb break strength), the same as that of new rope (100% overall strength). Once exposed to fatigue treatment, the dirty ropes’ overall strength dropped linearly with greater fatigue. There was a maximum drop in strength of 63% and a minimum drop in strength of 22% in the dirty rope group. The maximum decrease in strength of the clean rope was 25% with a minimum of 2%. It can be concluded that proper cleaning and care is essential to maintaining strong, safe ropes.