1. But#

The aim of operator PROPA_FISS is to cause a crack to propagate, this crack being defined with the X- FEM method. Three types of methods are available:

a method based on a*fast marching algorithm (METHODE_PROPA =” SIMPLEXE “,” UPWIND “): this method is available in 2D and 3D for all types of finite elements. The initial crack can be defined on the model mesh or on an auxiliary mesh.

  • a purely geometric method by calculating distances to the crack front (METHODE_PROPA =” GEOMETRIQUE “)

  • a method using an intermediate surface mesh of the crack lip (METHODE_PROPA =” MAILLAGE “): this method is available in 2D and 3D for all types of finite elements. The initial crack must also be defined using a mesh.

The operator PROPA_FISS thus calculates the crack resulting from fatigue propagation according to a local Paris law, from the previous crack, and from the table of stress intensity factors from CALC_G or POST_K1_K2_K3.

For half-straight cracks (in 2D) or plane cracks with a rectilinear background (in 3D), the surface mesh of the initial crack can be created by the operator PROPA_FISS (METHODE_PROPA = “INITIALISATION”).

The operator produces:

  • or a fiss_xfem concept defining the propagated crack (case METHODE_PROPA =” SIMPLEXE “,” UPWIND “or” GEOMETRIQUE “);

  • or the mesh of the initial crack (case METHODE_PROPA =” INITIALISATION “);

  • or the mesh of the propagated crack (case METHODE_PROPA =” MAILLAGE “).

  • The theoretical aspect of the propagation of level-sets for the X- FEM method is discussed in [R7.02.12].