Failure analysis of a sleeper anchor model used in railroads

The sleeper anchors are important elements in railroads. They are introduced into the ballast, and, as the name suggest, they have an anchor function, increasing the railway stiffness. Many rail companies have used a double fixing sleeper anchor model for many years. However, with the increasing of the transported load last decades, this model has failed in service, allowing the undesired ballast movement and creating a dangerous situation, with imminent risk of accidents. In this context, this work presents a complete failure analysis of this sleeper anchor model. Chemical, macro and microstructural analysis were done, and mechanical tests were performed. An alternative European model was also characterized, aiming to compare their metallurgical characteristics. The obtained results showed that the recurrent failures are associated to an overload applied to the studied device. This overload promotes an undesirable plastic strain and the anchor is removed from the ballast. It was possible to conclude that the mechanical properties of this double fixation anchor do not meet the specifications for the actual load demand in railways. The European model presented best characteristics for this application.