Abstract:

Ropes and woven webbing used in personal equipment protecting against falls from a height determine the course of forces acting on the human body during fall arrest, as well as the fall arrest distance. This paper presents a model of a system made up of a textile connecting and shock-absorbing component and the mass constituting its load. The model is based on non-linear rheological models of visco-elasto-plastic objects developed by Maxwell and Kelvin-Voigt. The definite structure of the model is described with a nonlinear differential equation, enabling numerical analysis of its performance. Identification of the model parameters was carried out utilising a software package allowing to analyse the static load-elongation characteristics and the time courses of a dynamic force acting during fall arrest. The paper presents the results of identification of selected connecting and shock-absorbing components used in equipment protecting against falls from a height. The models identified were subjected to verification involving comparison of their numerically simulated response with the results of laboratory tests. The comparison demonstrated the correctness of the model structure and identification of its parameters. The paper also presents an example of application of the model for simulation of the performance of a connecting and shock-absorbing component during fall arrest.