Crack interaction with incrementally accumulated plastic deformation under nonstationary thermal actions

• Ductile structural elements often experience both ratchetting and stable crack growth.
• Experiment shows that strain accumulation can lead to substantial crack opening.
• The finite element analysis of the experiment was made to obtain strain history.
• Critical damage analysis showed that the quasistatic damage exceeds the fatigue one.
• A cyclic crack can be driven mostly by a quasistatic opening rather than by fatigue.

One of the failure modes of ductile structural elements undergoing repeated thermal loading is incremental collapse caused by strain accumulation. Another failure mode typical for such loading is the stable growth of long cracks, with the crack being able to achieve the size of thermal tension zone movement. The impact of general incremental deformation accumulation on cyclic crack growth under repeated thermal actions is studied in this paper. The computational interpretation of the experiment shows that the static damage resulted from overall incremental deformation accumulation exceeds the fatigue one caused by reversed plasticity. This fact proves that under severe thermal ratchetting a crack can be driven mostly by a quasistatic opening produced by the strain accumulated within a body rather than by fatigue.