Exercise 1: Kinematic Draping for a Woven Ply Modeled with Two UDs

A dome is covered by a fabric. The fabric is idealized with two uni-directional plies. This method allows the material to be a simple, orthotropic, uni-directional ply level model. If the ply was modeled as a single woven ply, the material model would be anisotropic and vary spatially as the angle between the warp and weft directions changed. Nominal thickness of the uni-directional plies is 0.5 * woven thickness.

This exercise uses the dome.hm file, which can be found in the hm.zip file. Copy the file from this directory to your working directory.

Load the User Profile

In this task you will load the OptiStruct user profile.

  1. Start HyperMesh Desktop.
  2. In the User Profile dialog, select OptiStruct.
  3. Click OK.

Open the Model File

In this task you will open the model file, dome.hm.

  1. Open a model file by clicking File > Open > Model from the menu bar, or by clicking on the Standard toolbar.
  2. In the Open Model dialog, open the dome.hm file.
    The model appears in the graphics area.

Drape Plies and Review Results

In this task you will drape the uni-directional plies.

  1. In the Model Browser, select the plies folder.
  2. Right-click and select Drape > Kinematic Drape from the context menu.
  3. On the Drape Calculation tab, specify the Seed Point (id=5366). This is the location the ply first touches the mold.
  4. Leave method set to Quadrants. This method simulates a ply which is placed on the mold at the seed point, and is then pressed to the mold uniformly in all directions. Alternatively, Linear can be used. This method simulates a ply which is placed on the mold at the seed point, is then pressed to the mold along the fiber direction in a narrow strip, and is finally pressed to the mold uniformly from the fiber strip in the matrix direction.
  5. Click Apply.
    Note: The second ply will throw a message in the bottom left of the screen, indicating that maximum shear was exceeded. This indicates that the fiber locking angle of the fabric was reached. By default, drape angles for any elements in this condition will be set to reflect a locked angle and no further action is required. Alternatively, the ply(s) can be draped again using a larger Max. shear angle in the Advanced options menu.

Review Results

  1. From the Review tab, visualize the Draping Mesh for the first ply, which idealizes the warp direction of the fabric.
  2. From the Review tab, visualize the Draping Mesh to verify identical draping mesh as in the first UD ply.
  3. Turn on Composite Layers with Fiber Direction by clicking on the Visualization toolbar. This visualizes fiber directions for both uni-directional plies.
    The dome draping results are compared to [10] in the following image.

    Figure 1.