The structural model allows you to model linear elasticity for composite materials. Most composite materials exhibit orthotropic material properties, however, their material axes in the structural zone are rarely constant and instead follow the shape of the body, making them locally orthotropic.

To model locally orthotropic composite materials, you can follow the procedure for orthotropic material specification described in Orthotropic Materials. However, the material orientation shown in Figure 17.2: Orthotropic Youngs Modulus Dialog must be defined using a local material coordinate system.

The local material coordinate system is used to create local material directions that are consistent with the local material lines or surfaces. In 3D, the Direction 0 Components are typically specified as normal to the local material surface, while the material axes 1 and 2 are in the local plane normal to direction 0.

To create a local material coordinate system, you can follow the procedure outlined in Curvilinear Coordinate Systems in the Fluent User's Guide to create a curvilinear coordinate system. Once created, you can select the curvilinear coordinate system under the Coordinate System option in the Material Orientation tab in the Cell Zone Conditions panel. This ensures that the structural solver uses the local material coordinate system for the specification of local material axes.

Once created, you can select the curvilinear coordinate system by following the procedure below:

After selecting the curvilinear coordinate system for the local material, structural solver will use that system for local material axes specification.

Details on the settings described in the procedure above can be found in Inputs for Solid Zones in the Fluent User's Guide.