A new methodology for analysing the fatigue behaviour of filled natural rubber using rotating shear deformation experiments and FEM analysis

Understanding the fatigue behaviour of natural rubber is crucial for designing rubber components such as chassis and motor mounts. These components experience multiaxial loading during operation, which affects both mechanical behaviour and lifetime, for instance, due to self-heating or strain-induced crystallisation. In this study, a new methodology is introduced to analyse the fatigue behaviour of natural rubber under multiaxial loading. The loading is applied to the rubber sample through rotating shear deformation. A straightforward experimental set-up is employed to perform fatigue tests, where parameters like deformation amplitude and stress ratio are predetermined using a simulation model. Using this model, two load ratios for the tests are set. With the same amplitude loading, a higher load ratio provides lifetime reinforcement. The predicted behaviour aligns with the literature on natural rubber. A thermomechanically coupled finite viscoelastic model is used to determine the surface and internal temperatures of the sample. The predicted surface temperature and forces show good agreement with experimental results. This methodology provides valuable insights into how temperature distribution, local stress variation, and the stress ratio impact mechanical behaviour and fatigue life.