Automatic and Adaptive Finite Element Mesh Generation For Full 3D Fatigue Crack Growth
G.Cook, C.Timbrell, P.W.Claydon
STRUCENG & FEMCAD Conference, Grenoble, France, 1990
Abstract:
A method is presented for automatically generating meshes containing
3D crack fronts. Further, an adaptive meshing scheme is presented
for automatically updating meshes during full 3D fatigue crack growth
prediction.
Cracks are introduced into a valid mesh of the intact component by
a mapping scheme which replaces standard 20 noded brick elements with 'superelements'. In the context of this paper, the term 'superelement'
refers to a set of 20 noded brick elements which models a quarter
circular or through crack front using collapsed 'quarter point node'
brick elements. Replacement of elements in a mesh allows introduction
of one or more distinct crack fronts, with more than one superelement
permitted on each distinct crack front. A special mapping controls
the crack size in each superelement and maintains original isoparametric
surfaces thus creating a valid mesh for the cracked component. Following
incremental fatigue crack growth prediction, all superelements
are re-mapped to obtain a mesh with the new crack position. The mapping
scheme allows non-planar crack growth in 3D geometries.
The procedure has been found to be flexible, efficient and a great
time saver in 3D fatigue crack growth analyses. Good agreement with
experimental fatigue crack growth data has been demonstrated using
this meshing scheme.