Data Mapping

What is Data Mapping?

Data Mapping is a functionality allowing load import described by a scalar field from a text (.txt) or an Excel (.xls) file. This file must respect a pre-defined format.

You can re-use data that are external data (experimental data or data coming from in-house codes or procedures).
The imported values will be interpolated at the center of gravity of each element.
You can also integrate user loading knowledge and processes into this version.

The selected external data file will be either a .txt file (columns separated using the Tab key) or a .xls file. This file must respect a pre-defined format.

Data Mapping is useful when you want to re-use a load field created without CATIA or with a former version of CATIA.

How are Data Mapping files filled?

Data Mapping files are text files (.txt) or Excel files (.xls) that must respect a pre-defined format.

For pressures, line force densities, surface force densities, body loads, temperatures, and shell properties, the data mapping file must respect the following format:

• Four columns.
• Each cell must contain a numerical value.
• The first three columns allow you to specify X, Y and Z point coordinates in the global axis.
  Unit symbol written between parentheses must be specified.
• The last one allows you to specify the amplification coefficient.
  No unit symbol must be specified for the last column (the amplification coefficient is not assigned to a dimensional value).

Example of data mapping for a pressure:

For imported forces and imported moments, the data mapping files must respect the following format:

• Six columns.
• Each cell must contain a numerical value.
• The first three columns allow you to specify X, Y and Z point coordinates in the global axis.
  Unit symbol written between parentheses must be specified.
• The last three columns allow you to specify FX, FY and FZ force coordinates in the global axis in case of imported forces or MX, MY and MZ moment coordinates in case of imported moment.
  Unit symbol written between parentheses must be specified.

Example of data mapping for an imported force:

Which algorithm is used for Data Mapping?

For pressures, line force densities, surface force densities, volume force densities, temperatures, and shell properties, there are three steps in the data mapping algorithm:

1. Checking that the center of gravity of each entity of the recipient mesh is inside the bounding box of the source mesh (automatic tolerance: 1.0 e^-3 m).

   An entity can be an element, an edge or a face. For example: For a temperature field, entity means element. For a line force density, entity means edge. For a pressure, entity means face.

2. Matching the center of gravity of each entity of the recipient mesh with some of the nearest points of the scalar field. For a 2D mapping, the matching is done with the three nearest points that define a triangle containing the center of gravity; for a 3D mapping, the matching is done with the four nearest points that define a tetrahedron containing the center of gravity.

   Example of a shell element:
   	These points are processed as if they were the vertices of a finite element. The matching is done at the centers of gravity of the recipient mesh entities, and not at their nodes, because it is the resulting loads location.

3. Interpolating the scalar field of the source mesh on the recipient mesh using the nodal functions of the finite element.

With this algorithm, some mapping points may be unused.
Consider the example of a 2D mapping: to compute a pressure value at the center of gravity, the algorithm selects the three nearest points that define a triangle containing the center of gravity. Then the shape function of the triangle is used to compute the value at the center of gravity. If the nodes density in the mapping is greater than the mesh node density, some of the mapping points may be unused and the final value may be truncated.

For imported forces and imported moments, the following algorithm is done for all mapping points:

1. Checking that a mapping point can be projected on an element face.

2. Transferring the load at this mapping point to the nodes of this element face using the shape function of this face.

In which functionalities is the Data Mapping process available?

The Data Mapping process is available in the following functionalities:

• pressure
• line force density
• surface force density
• volume force density
• temperature field
• shell property
• imported force
• imported moment