Effective Fatigue Evaluation on Rubber Mounts for Rail Vehicles

The accurate evaluation of fatigue damage is a key issue in designs for rubber antivibration mounts. To find the most cost-effective route for antivibration design, a fatigue criterion (effective stress) was fully (including both magnitude and orientation) applied to the suspension components of rail vehicles, i.e., a longitudinal buffer and sandwich products. Hyperelastic models, widely applicable to industry, were used for load-deflection calculations and validated with the experimental data. The fatigue cracks were located at the points where the effective stress reached its maximum. The orientation prediction correlated with the experimental observations. For the buffer, the predicted crack initiation was approximately 45 k cycles at the top interface and 80 k cycles at the bottom interface, whereas nearly complete debonding in the top interface and ring-shape debonding in the bottom interface were experimentally observed at 200 k cycles. For the sandwich mount, 150 k cycles for crack initiation were predicted against 380 k cycles with an observed crack length measuring approximately 150 mm from the fatigue test. Furthermore, an important aspect was that the orientation of the cracks was defined in analytical functions so that an expensive critical plane search could be evaded, which would save 99% of calculations (144 calculations are needed for three-dimension analysis if the rotation angle is 15°, whereas only 1 calculation is required using the proposed methodology). As limited cases were verified, more engineering cases would be needed to verify this approach further.