About Laminates

Below is some information about the role of the laminates and the evolution of their data representation.

The main input for the Composites designers is:

• The reference surface that supports the plies (main geometry).
• The zone map and stacking table coming from the stress office, resulting from a FEA analysis.

The stacking table (typically given as a spreadsheet) defines the requested laminate for each zone of the reference surface. The laminates ensure that the structure resists to the expected stress.

A laminate can be given as:

• A stacking sequence, that defines precisely the stacking as an up-down ordered list of layers, characterized by their material, orientation, and possibly a layer key.
• A thickness law, that only indicates the number of layers for each couple of material/direction used.
• A Main Stacking Sequence, that is an ordered list of layers. Each layer is defined by its material and direction, and optionally a layer level and a layer name.

A thickness law can be retrieved from a stacking sequence, whereas several stacking sequences correspond to a same thickness law.

Before V6R2013x, the laminate is dealt with differently by the Grid Approach and the Solid Approach:

• In the Solid Approach, the laminate is explicitly implemented as a feature visible in the tree, under each zone. The laminate is defined for a given zone, and can only be edited as a thickness law: for one or several materials, the number of layers is given for each possible orientation. Designers can select an existing laminate in the tree and fill in the thickness law directly from it.
• In the Grid Approach, the laminate is not explicitly implemented as a feature, and is not visible in the tree. For each cell of the grid, the laminate can be defined as a stacking sequence, or as a thickness law. Two laminates can be defined: The reference one, and a modified one. Laminates can be defined globally for all the cells by importing/exporting a grid definition file, and stacking can be propagated to several cells.

In V6R2013x laminates have been enhanced to extended laminates:

• Extended laminates can be defined at the start of the design, using Composites Parameters, or later, while editing grids or zones.
  • The extended laminates can be explicitly defined either as a stacking sequence or a thickness law, using Composites Parameters, in both Grid Approach and Solid Approach.
    Note: Definition as a stacking sequence is possible in Solid Approach, for compliance reasons. However, the laminate is considered as defined by a thickness law, meaning the material is defined for a given zone and edited only as a thickness law.
  • They can also be implicitly defined when importing grid data from external data or from a virtual stacking: extended laminates are created if existing ones do not cover the needs, that is, if the stacking used for a cell does not correspond to an existing extended laminate.
  • Both Excel and text file formats are supported to define the laminates through import/export capabilities.
  • New laminates can be created on the fly, without exiting the grid cell or zone definition commands. They are visible under Composites Parameters.
  • Automatic creation of extended laminates with grid cell or zone definition commands can be de-activated, to use only validated extended laminates (for example for compliance with in-house rules).
  • Information is displayed when extended laminates have been created after an import, or when automatic creation is disabled and missing laminates are found.
• The list of laminates is visible at a glance under the Composites Parameters node in the tree.
• Existing laminates are easy to reuse.
• Laminates can be renamed to meet a company standard.
• A color is associated to each laminate for a more stable 3D visualization.
• Each cell of a grid (Grid Approach), or zone (Solid Approach) points to an extended laminate to define its local stacking. A grid cell can point to two extended laminates (reference and modified).

An automatic migration to extended laminates is started when you open an old model, that creates a laminate object for each laminate found in grids and zones.

You can import a spreadsheet defining a Main Stacking Sequence and all associated laminates to be used in a model (one laminate per column).

This spreadsheet looks as follows:

You can define laminates by exporting their definition as an external file, modifying it and reimporting it.

Both Excel and text files are supported.

• Example of definition:

  Name    TL.1
  ColorIdx          1
  Type    TL
  Stacking          0    45    -45    90
  U174_T800         18   6     6      4
  #
  Name    SS.1
  ColorIdx          2
  Type    SS
  Stacking
  U174_T800         0
  U174_T800         45
  U174_T800         45
  U174_T800         45
  U174_T800         -45
  U174_T800         -45
  U174_T800         -45
  U174_T800         90
  U174_T800         90
  U174_T800         -45
  U174_T800         -45
  U174_T800         -45
  U174_T800         45
  U174_T800         45
  U174_T800         45
  U174_T800         0
  #
  Name    TL.2
  ColorIdx          3
  Type    TL
  Stacking          0    45    -45    90
  U174_T800         20   6     6      4
  #
  

Although this is not the recommended way, it is possible to import the laminates from a grid definition file, exported as explained in Export/Import Grid Data, as this file contains both information on the grid and on the laminates. However, the information on the grid is not taken into account. In particular, if you re-export the laminates obtained this way from the Composites Parameters dialog box, the information on the grid is lost in the export file.

The Import Laminate command is also different, as it imports laminates information specific to defined zones, given as thickness laws, without color data, whereas Composites Parameters imports full laminates information, with stacking defined either as thickness laws or stacking sequences.