Variationally Consistent Phase-field Models for Desiccation Cracking

  • Bharali, Ritukesh (Chalmers University of Technology)
  • Larsson, Fredrik (Chalmers University of Technology)
  • Jänicke, Ralf (Technische Universität Braunschweig)
  • Paul van der Meer, Frans (Delft University of Technology)

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In this work, variationally consistent conventional and micromorphic phase-field models are proposed for desiccation cracking. To this end, the conventional energy functional pertaining to the linear elastic single phase media is extended towards two-phase partially saturated porous media. This extension involves the addition of a coupled term, which is an integral of the product between the water pressure and the porosity change. A new phase-field dependent function is attached to this term, which acts as a degradation term when suction (negative pressure) is encountered, otherwise it attains a value one. This yields a novel phase-field evolution equation, where the suction provides an additional energetic contribution to the desiccation cracking phenomenon. In previous studies by [1], the suction contribution was ignored. Numerical experiments on the benchmark Peron's desiccation experiment [2] illustrates the acceleration of the desiccation cracking process upon incorporating the suction contribution. Similar results were also obtained in [3], however in a variationally inconsistent framework. Additionally, the novel framework in this contribution is then extended in the spirit of a micromorphic media [4]. The micromorphic model retains the phase-field fracture length-scale, however, with a new variable for regularization. The phase-field is transformed into a local quantity (evaluated at integration points), which enables fracture irreversibility enforcement with system-level precision. Finally, numerical studies are performed to calibrate the micromorphic phase-field fracture model for desiccation cracking.