Preform Material Data and Draping Computations

A preform is modeled as a porous medium, and the mathematical modeling uses Darcy's model. Hence, the preform is characterized using permeability tensor.

Draping computations play a crucial role in determining the tensor material properties. This data has to be transformed at each solution integration point using the local coordinate orientation. This is essential for the RTM process, and it is seen in the image below. The preform, which is characterized in a flat orientation, is draped to take the shape of the mold before the RTM process begins. To simulate the process, the material data is required in local orientation based on the mold shape.

Preforms are characterized in a flat orientation. That is, its material properties such as permeability tensor, conductivity tensor, specific heat, etc. are measured in this orientation. The process of shaping the preform to its final product shape is called the draping operation. Often what is measured as an orthotopic tensor in a flat orientation will be a full tensor in its draped position. This transformation has to be computed to perform the simulation.

The draping computation has many internal steps, and HyperMesh is used for this analysis. The details of the process, shown in the figure below, are completely automated and hidden in Inspire. It is computed in batch mode. RTM Solver uses this exported ply orientation to compute material data in each integration point.

1. For complex models, the automatic midsurface extraction may fail. The workaround is to create the midsurface manually and Inspire will use that interface and not try to create one automatically.
2. Inspire does not support post-processing of draping results.