Method 1 Method 2 (simplified) Composite FEA Methods The ‘usual’ FE method is to use FE Plate Composite Elements. The advantage of this approach is that inter-lamina failure can be calculated in addition to global stress levels. The various layers that define the composite are defined (usually in a table within the FE program). This method relies on ‘knowing’ the mechanical properties of each layer. Unfortunately this ’Plate’ method generally requires a CAD mid-plane surface model and not a 3D Solid volume model. Virtually 100% of CAD models created by Designers are 3D Solid models. This solid geometry needs to be converted into mid- plane CAD surface geometry and is a skilled job that we regularly perform. A second approach would be to test * samples of the Composite (complete with multi-layers/angles etc) and then derive Global material properties. These can then be applied to the Elements within the FEA. This has the advantage of using actual test data and could be applied to Plate AND Solid Elements. The disadvantage of this approach is that inter-Lamina failure calculations are not possible because we have tested the complete layup in one, amorphous, sample and applied it to the FE model. * Testing could also mean the creation of global properties via software to define the various layers.