Mark Obstalecki

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

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.

Utilizing Knots to Reduce Dynamic Loads in Fire Service Rope Systems

Rope systems are commonly used in applications including recreational sport climbing, industrial fall protection, and Fire Service rescue. These rope systems must be able to absorb energy in order to reduce the risk of impact injury to the individual experiencing the fall. However, there are several factors that go into the selection of the rope based on end use condition, whether that is weight, abrasion resistance or heat resistance. Thus some of the properties that are required for ropes to be effectively deployed for escape scenarios in the Fire Service, do not translate to optimal energy absorbing capabilities to prevent injuries to the individual attached to the system.

InSitμ@CHESS, a Resource for Studying Structural Materials

High-energy X-ray diffraction (HEXD) experiments, which include real-time measurements of micromechanical material response using in-situ loading and the non-destructive creation of three-dimensional maps of polycrystalline microstructure, are very rapidly replacing traditional macroscopic mechanical tests and forensic metallurgical characterization methods for structural materials. The center for Integrated Simulation and X-ray Interrogation Tools and Training for Micromechanics at the Cornell High Energy Synchrotron Source (InSitμ@CHESS) was created to facilitate the use of HEXD experiments on structural materials; more notably, metallic alloys such as steel, titanium, aluminum, and nickel. The Office of Naval Research (ONR) has financially supported InSitμ, specifically enabling enhanced industrial user support. This article describes the experimental considerations associated with using HEXD on structural materials and, through a set of examples, illustrates how InSitμ addresses these considerations.