About Plies Creation from Virtual Stacking

General Information

• The contour of the plies are based on the sequence shapes (cell coverage) and on the initial staggering defined on structural elements during the panel creation. If the staggering parameters are set to 0, a warning message is issued.
• Starting with V5-6R2014, selecting a ply shape from the stacking order or the cell coverage is no longer required.
  
• The drop-offs are directly optimized for each group of plies with the same shape.
  A pattern is applied depending on that shape.
  This ensures a better result, and less future rework of the generated plies.
• A ramp support is a section of the structural element from which a group of plies drops off.
• Ramp supports are automatically computed. However they can be edited.
• The definition of the limitation side of limit contours is taken into account.
• If you generate a second plies group from a virtual stacking that already contains a plies group,
  only the plies group created first will be synchronized with the virtual stacking
  (the second one will not be synchronized).

Plies are generated as follows:

• Ramp supports are grouped by structural elements groups and by side.
• The stacking is generated with ply contours based on the ramp entity curves.
• To reduce the number of useless ramp support curves, one ramp support is created for each structural element per side (+1 and/or-1).

• You must have switched to upgraded rosette mode.
• Surface, lay-up direction and rosette of the plies group must be the same as for the grid panel of the virtual stacking.
• If the ply group had been defined with layer levels, and if some layer levels are now missing, update is not possible.
• The names of the virtual plies and virtual sequences in the virtual stacking must be unique.
• There cannot be a mix of plies and cores inside the same sequence.
• Ramp support fallback strategies are not stored in the plies group.
  They are retrieved from the parameters set in this command.
• When necessary, the old plies group is migrated to automatic shells mode.
• If a ply of the old plies group is not in the newly generated plies, it is deleted.
• Empty sequences are deleted.
• If a newly generated ply is not in the old plies group, it is added. The corresponding sequence is created if needed.
• Sequences are renamed if needed.
• All modifications of the plies attributes are carried over to the existing plies.
• For each ply, new contours are compared to old ones:
  • In most cases, plies have a single contour. If the old and new contour have a similar definition, the old one is left unchanged. Otherwise, it is updated from the new input list.
    Note that two contours may have a different but similar definition: They have the same curves but in reverse order.
  • When a ply has several contours, they are compared in their order in list. Extra contours are added, missing ones are removed.
  • Only first standard contours are analyzed. Other (limit contours, rounded corners, material addition, material excess,...) are ignored.
  • If the contour inputs are modified, the contour is upgraded.
• If a newly generated ply is located in a different sequence, due to change in cell covering, the existing ply is moved accordingly.
• When needed, plies are re-ordered in existing sequences and existing sequences are re-ordered in the plies group to match the temporary plies group.

Case of Staggering or Weight Saving Steps

Let's consider the following example:

• Cell gauges are as follows
  
  with the following staggering defined for vertical
  
  and horizontal structure reference elements
  
• Plies are generated as follows:
  
  In a detailed view:
  
  Steps appear in the ply shapes because of staggering change on the horizontal structure reference element.
  They could also appear for weight saving reason.
• The staggering definition used for these steps is that of the yellow plies.
  It is the staggering definition below the grid node on the vertical structure reference element.
  This ensures a constant ramp in the white dotted line region.
  

Let's consider another example with different cell gauges and the same staggering definitions as previously:

resulting in

Although there are no ply drops between the cells below the node, the staggering step uses the staggering definition
below the grid node on the vertical surface reference element (same as in previous example):

• As a designer, you might have used the staggering definition above the grid node for the step.
• However, to be consistent with the first example, and with all cases, the chosen algorithm is that of the first example.