# 18. Phase Field Fracture

A phase-field fracture model has been implemented as a means of providing a mesh-convergent failure modeling capability. Usage of the phase-field fracture capability involves two primary components: (1) using a specific phase-field material model (Phase Field FeFp) and (2) establishing a solver to determine the phase field update. The phase-field material model is implemented in the LAMÉ material library and includes all model form choices and model input parameters; this is documented in the LAMÉ manual. The phase-field solver is implemented in Sierra/SM (reaction-diffusion solver) and is documented in this chapter. This includes documentation of the reaction-diffusion solver itself, as well as the control reaction diffusion block, which is used in implicit analyses. Additional usage and debugging guidelines are provided.