Fatigue of Constructional Steel S460 under Complex Cyclic Stress and Strain Sequences

The constructional fine-grained steel S460 shows considerably high fatigue performance. In the last two decades this material has been investigated experimentally in great detail. These results served as basis for developing models and algorithms aiming at improvement of fatigue life assessments. The paper summarizes both the cyclic deformation and failure behaviour. The experimental results are compared with the results obtained by applying the models. Simple uniaxial loading is addressed also as a complex multiaxial, non-proportional elastic-plastic straining. The deformation behaviour is described by an enhanced plasticitymodel based on continuum mechanics principles. Cyclic softening and hardening, ratcheting and cyclic mean stress relaxation as well as non-proportional hardening are taken into account. The fatigue cracking behaviour is modelled based on a critical plane approach where the short crack growth calculations determine the critical plane of shortest fatigue life.