Nonlinear thermo-elastic phase-field fracture of thin-walled structures relying on solid shell concepts

The analysis of fracture phenomena of thin-walled structures has been a matter of intensive research in the last decades. These phenomena notably restrict the applicability of slender structures, especially under the influence of temperature. With the aim of achieving reliable prediction of temperature-driven failures in thin-walled structures, this research is concerned with the development of a thermodynamically consistent framework for the coupled thermo-mechanical phase-field model for thin-walled structures using fully-integrated solid shell finite elements. This enables the use of three-dimensional constitutive thermo-mechanical models for the materials. The proposed thermo-mechanical phase-field models are equipped with the Enhanced Assumed Strain (EAS) in order to alleviate Poisson and volumetric locking pathologies. This technique is further combined with the Assumed Natural Strain (ANS) method leading to a locking-free thermo-mechanical solid shell phase-field element. Attention is also paid to the evaluation of the corresponding thermodynamic consistency and the variational formalism leading to the non-linear coupled equations. Moreover, the same degradation function is used for both displacement field and thermal field. The coupled equations are numerically solved with ad hoc efficient solution schemes for non-linear problems. Several numerical examples (straight and curved shells) are provided to assess the reliability of the proposed modelling framework. Representative examples assess stable and unstable crack propagation along with their thermo-mechanical interactions.