Software > Zencrack > Technical > Meshing procedure > Crack growth

Crack growth

During a crack growth analysis Zencrack carries out a number of steps to re-generate the mesh with an advanced crack position. This advancement of the crack simulates the crack growth in the structure:

  • Process the results of a finite element analysis to determine fracture mechanics parameters
  • Integrate these data with the crack growth law and load history to calculate growth at each crack front node
  • Re-distribute nodes along the crack front if necessary to maintain outer surfaces
  • Check whether the crack-blocks need to be transferred to the next line of elements
  • Apply boundary shifts to the outer regions of the replaced elements (if necessary)
  • Apply relaxation to the elements surrounding the replaced elements (if necessary)
  • Re-map the internal nodes of the crack-blocks taking account of the current crack front(s) and any non-planar crack history.

For some classes of problem the boundary shifting algorithm is extended to allow crack-block transfer from one element location to another. This enables large scale crack growth through the structure. The example below shows this type of crack-block transfer. The highlighted nodes are identified as the local radius around the crack front in which the mesh is modified by mesh relaxation during the remeshing procedure.

Example of mesh relaxation

The crack growth examples section provides a number of examples that demonstrate the effectiveness of the re-meshing capabilities within Zencrack during a crack growth analysis. Two examples are highlighted here, the second of which gives a further demonstration of the crack-block transfer capability in Zencrack.

Growth and interaction of multiple surface cracks.

Growth from a bolt hole in a gas turbine compressor disk spin test.
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