Crack Paths 2006

6. T H EC R A C K ES DT R U C T U R E

Finally, the duplicated crack and the perforated structure are merged together. Triangles of the

crack faces external to the perforated structure and triangles of the perforated structure

between the crack faces have to be deleted. The routines used are the same as for merging the

cylinder and the uncracked structure. The final cracked structure is illustrated in Figure 8.

Figure 8. The final cracked structure (without and with the triangular surface mesh displayed).

1.

7. F U T U RWE O R K

The automatic insertion of the crack is hereby complete. There is, however, plenty of work to

2.

come before the crack growth increment can be calculated. The remaining tasks are:

3.

Identifying the sharp edges before calling a tetrahedral mesher.

Generation of the tetrahedral mesh, for instance with N E T G E[N5].

4.

Generation of hexahedral elements inside the flexible cylinder.

Cutting of the hexahedral elements with the triangulation of the uncracked structure.

5.

Connecting the hexahedral and the tetrahedral elements with linear MPC’s.

6.

Transferring the loads and boundary conditions from the uncracked to the cracked

structure.

7. Calculating the K-factors and crack growth increment by use of finite element

calculations.

8. C O N C L U D IRNEGM A R K S

Triangulation of the surface of the cracked structure has been accomplished, including the

key-hole at the crack-front. The program has been developed at M T Uas a M S cProject [6]

and works fine for arbitrarily shaped cracks and structures.

R E F E R E N C E S