Comparative analysis of mechanical tensile tests and the explicit simulation of a brake energy dissipater by FEM

The use of brakes or energy dissipaters in the anchorages of rockfall barriers is based on their great slip resistance capacity. The brake energy dissipaters can dissipate the kinetic energy produced by the impact of rocks, which is transmitted to them through the system made up of a network of wires, poles, guided cables and anchorages. The dissipaters transform kinetic energy into heat through their deformation (strain), thus increasing the dynamic performance of the screens against falling rocks. These dissipating elements consist of two tubular steel loops (bearing ropes, ties) joined by two aluminium compression sleeves at its extremities, which are under pressure depending on the slip resistance that is desired. In this work a comparative analysis of results obtained from two tensile tests is carried out simulating the slip of the brake energy dissipaters when they are working. The first tests were carried out with a static tensile load. These tests were conducted on a bench with a hydraulic jack varying the tightening pressure on the dissipater's compression sleeves. The second test was the nonlinear dynamic simulation of symmetrical tensile tests and fixed point of the brake energy dissipater. This simulation was performed using the explicit finite element method (FEM), varying the coefficients of friction and speed of slippage between the bearing ropes. The numerical results of these studies show the correlation between the dissipation energy in the tensile tests and the fixed point between the two experiments. In addition, some complementary improvements with respect to the location and geometry of the design of these brake energy dissipaters are made by correcting the efficiency of brake energy dissipater and anchorage set of the rockfall barriers. © Freund Publishing House Ltd.