ABAQUS user-element subroutine (UEL) with phase field fatigue (and fracture). Includes an input file for using Quasi-Newton to run in a robust monolithic manner and a document with detailed instructions.
Paper: P.K. Kristensen, E. Martínez-Pañeda. Phase field fracture modelling using quasi-Newton methods and a new adaptive step scheme. Theoretical and Applied Fracture Mechanics 107: 102446 (2020)