An Approach for Quantifying Dynamic Properties and Simulated Deployment Loading of Fire Service Escape Rope Systems

Abstract

Rope systems are simple mechanical structures that provide life-critical protection from dynamic loading in a variety of applications where falls from height are possible. Recently, the Fire Service has realized the importance of using fall protection systems while endeavoring to gain a better understanding of how these systems will respond during fire ground deployments. A new extensometer, utilizing a linear variable differential transformer, was designed to advance the ability to characterize the dynamic and static properties of these ropes. A series of experiments were conducted to replicate various deployment scenarios, quantifying the effect of fall height, payout length, and ledge geometry on the dynamic loads a firefighter and his/her equipment may expect in realistic escape scenarios utilizing common rope systems. These loads are compared to occupational health-safety-based maximum load recommendations and the quasistatic strength of the rope. While the ropes constructed from all aramid fibers were the strongest in standard quasistatic tests; during dynamic loading they generated the largest maximum arrest loads that were consistently above the occupational health-safety recommended load of 8 kN. Finally, using the experimentally determined rope properties measured with the new extensometer, positive agreement was found between the experimental drop tests and numerical simulations.

Fatigue and impact load: Experimental investigation on mechanical behavior of high modulus polyethylene yarns

“…These types of ropes have a polyamide core and aramid braided jacket due to its resistance to high temperatures. 9 Polyester ropes are historically used as mooring lines and are also responsible for the sailing controlling system. 1 HMPE (high modulus polyethylene) yarns are currently used in numerous applications, including medical, ballistic protection, offshore mooring/operation lines, sports, cargo lifting and in the robotic field, due to their high strength and low weight, combined with excellent mechanicalfor instance, pronounced abrasion and cutting resistance -and chemical properties.…”

“…Material stiffness can be exceptionally high in relation to other fibers, allowing it to be subjected to a higher tension related to the same rope diameter. 9,11 Yarn degradation by dynamic loads Dynamic loads, long-term ones like fatigue or short-term ones like impact, may induce fiber degradation under operation, in correlation or not with chemical reactions. 16 Different types of loads can cause polymer chain rupture at different stages, like solid, molten, or in a solution.…”

“…These types of ropes have a polyamide core and aramid braided jacket due to its resistance to high temperatures. 9 Polyester ropes are historically used as mooring lines and are also responsible for the sailing controlling system. 1…”

“…Material stiffness can be exceptionally high in relation to other fibers, allowing it to be subjected to a higher tension related to the same rope diameter. 9,11…”

“…It was observed that more stiffness ropes have higher dynamic loads values. 9 A decrease in fiber impact resistance can be observed due to material physical conditioning and/or material degradation. For instance, polyamide fibers tend to have lower impact resistance under wet conditions.…”