ASSESSING THE DEFECT TOLERANCE OF RAILVEHICLE IMPACT ENERGY ABSORBERS

This paper investigates the dynamic response of the joints of energy absorbers used in rail vehicles. These energy absorbers are designed to deform in a controlled manner in the event of a collisions thereby absorbing some of the impact energy that would otherwise be transferred to the main structure and passengers. The functional requirements of these devices are particularly stringent in terms of their reliability and functionality throughout the life of the vehicle. In this work the merits of a welded and a bolted energy absorber design are investigated, the latter offering the advantage of ease of through life maintenance and replacement, ensuring that defects such as general corrosion or cracks that could have affected their performance are easily identified and replacements made. FEA modelling to simulate the dynamic response of welded and bolted joints has been carried out using the LS-DYNA code. For the welded joints the influence of welding defects such as lack of fusion, weld under matching, and weld cracking on the performance of the energy absorbers has been investigated. The numerical model, validated on the basis of results from impact tests, was subsequently used to investigate the behavior of the absorption system in collision scenarios as prescribed by EN 15227:2008.