III.1.2.2 Composite Results

This section is more specifically devoted to the composite Results (failure indices). Failure indices can be imported from “op2” files only. The different Results that can be imported from Nastran are summarized in Table III.1.17. One can make a few remarks about the information given in those Tables:

1.

Since version 3.4.2, the stress tensor in plies is produced in “Mid” sub-layer only. This means that the out-of-plane shear stress that Nastran calculates at bottom skin of each ply is displaced at mid-thickness of the ply. This is an approximation. (This out-of-plane shear stress can be used to calculate inter-laminar shear stress in composite.)

A rotation of the out-of-plane shear components is done in such a way that all components are given wrt ply axes. (Nastran outputs these components in laminate axes.)

2.

When Nastran composite strains are read, values are produced for Mid thickness of each ply only. Nothing is produced on ply upper or lower faces.

3.

The remarks done about the conversion of angular shear strain components to tensorial shear strain components are of course also valid for layered strain Results.

4.

Failure indices can be read from “op2” files only. Corresponding Results do not seem to be stored in “xdb” files.

The indices given in Table III.1.17 refer to the remarks above.

Four methods devoted to the enabling or disabling of composite layered Results are defined in the generic “DataBase” class. These methods are presented in section I.1.3.2.

The correspondence between the failure indices read from Nastran “op2” files and Results produced by CLA classes is as in Table III.1.18.