Testing, simulation and evaluation of a novel hybrid energy absorber

Railway vehicles require energy absorbers which dissipate energy at a constant load, resist transverse loading and which are compact. In addition, accurate numerical models of the crumple zones are also required. A novel expansion-splitting (hybrid) energy absorber is proposed by the authors to provide improved energy absorption properties over existing devices.

Dimensionally scaled tubes, incorporating expansion, splitting and expansion-splitting dies, were tested under quasi-static and dynamic conditions. Six different dies, with expansion ratio R = 1.10 and R1.25, die conical semi-angle A = 15° and A = 30° and flaring radii D = 8 mm and D = 12 mm, were used in the experiments to crush the tubes. Calibrated numerical models and parameters found in previous investigations (fracture strain and friction) were included in the numerical models of the expansion-splitting tubes.

For the quasi-static testing, the expansion tubes exhibited the greatest force efficiency. The splitting tubes exhibited the greatest stroke efficiency. However, the expansion-splitting tubes exhibited the greatest combined overall efficiency.

The numerical simulation accurately predicted the performance of the expansion-splitting tubes under quasi-static conditions. The energy absorption of these tubes was predicted within 2% of the observed test results.