Computational Methods for Debonding in Composites

286 W.-G. Jiang et al.
Fig. 14.2 Geometric parameters for a RVE of a plain weave composite
14.3.1 Convergence Study of DST
Although the technique of embedding two-noded beams into solid elements such as
the “binary model” [1, 7, 9, 10] has the benefit of substantially smaller model size,
these models are mesh size dependent. That is to say, when the FE mesh is refined
further, the results will change continuously rather than converge to the real state as
the modelled structure should behave. In contrast, DST is mesh density objective,
i.e. the simulation results will converge if the meshes are fine enough. To understand
the performance of DST, a mesh sensitivity study has been performed. In order to
simulate a more realistic woven geometry, the gap size at the crossing tows in the
model used for the analysis is set to zero (a = 0). It would be extremely difficult
to build a proper FE mesh for this special case with touching tows at the crossover.
However this is no longer an issue for DST analysis.
14.3.1.1 Mesh Refining Scheme 1
In the first mesh refining scheme, both global and tow meshes are re-fined simultaneously.
Typical DST finite element meshes used for the mesh effect study are
depicted in Fig. 14.3. The analysis results are given in Table 14.1. As desired, it can
be seen from this table that both stiffness and stress converge as the FE meshes are
refined.