Tutorial: Polymer Solid Extrusion

Learn about the Inspire Extrude Interface, set up and complete a solid profile extrusion analysis, and post-process the results for interpretation.

Open the Tutorial Model

Data files are available in the tutorial_models folder in the installation directory in Program Files\Altair\2021\InspireExtrudePolymer2021\tutorial_models\extrudepolymer\tutorial-1\.
Open the RubberTrimSolid.x_t tutorial model file from the file menu or by dragging and dropping the file into the Inspire Extrude window.
The model should appear in the Inspire Extrude window.

Orient the Model

  1. Click the Polymers ribbon.
  2. Click the Orient icon.

  3. On the model, click the exit surface.

    The model is oriented such that the profile is on the run-out table surface, which is at Y=0, and the profile extrudes in the +Z direction.

Extract Flow Volume

  1. Click the Polymers ribbon.
  2. Click the Flow Volume icon.

  3. Click and drag the cursor over the whole model to create a box select, then release.

Delete Unwanted Solids

  1. Orient the model such that selecting solids is easy.

  2. Select solids which belong to Flow Volume and hide them by pressing H.

  3. Delete the remaining solids.

  4. Press A to reveal the remaining solids.
  5. Hold CTRL and select multiple solids on the exterior of the model.

  6. Press H to hide the selected solids.

Select Materials

  1. Click the Materials icon.

  2. Select PVC > PVC_Generic
  3. Right click on the alloy name and select it.

    Note: Another way to search for your materials is to click in the search box in the materials window.
    1. Click in the search box.

    2. Type the name of the alloy.
    3. Right click on the alloy name and select it.

    Note: You can deselect a material by right-clicking on a selected material and clicking Deselect. This is a single polymer extrusion die, so you only need one polymer for this simulation.

Specify Process Data - Inlet

  1. Click the Inlet icon.

  2. Zoom in to the inlet region of the polymer melt and select the inlet face.

  3. Specify the inlet conditions.

Organize Solids into Polymer Layers

  1. Display only flow solids which define the polymer flow.

  2. Click the Organize icon.

    Inspire Extrude will combine the required solids, rename, and organize the selected solids to the Layer-1 assembly.

Create Profile Solids

  1. Click the Profile icon.

  2. Zoom in to the land surface as shown and click on that surface.

    Inspire Extrude will create a Profile solid and use 3 times the length of Land as its default. You can change this as needed. This model requires a 60mm Profile solid length. There is only one exit in this model, so you do not need to repeat this step.

Delete Die Assembly Solids

Select die plate solids that belong to the die assembly and delete them as shown. Reveal them by pressing A. These solids are not required for flow simulation and create issues in geometry cleanup.

Save the Model

Click File > Save As... to save the model.
Note: We suggest you save this new model in a location that is different than the original tutorial model's location to prevent any future conflict with those files.

Submit the Job for Simulation

  1. Click the Run Analysis icon.

  2. Specify parameters for the analysis process.

  3. Click Run.

Monitor Job Status

Once the results are ready, you should see a green flag above the Analysis icon notifying you that the results are ready for visualization.

Interpret Out File Data

The goal of post-processing is to interpret the results generated by the solver and apply them to validate/improve the design. Results generated by the solver are stored in two key files:
  1. Out file: This is an ASCII file, which helps to verify the input data and gives a quick overview of the result.
  2. H3D File: This is a Binary file with detailed results.
Note: Even though this section is built off the results from this specific tutorial, it has general applicability throughout any project in Inspire Extrude.
  1. Verify the Input data by checking these pieces of data:
    1. Solution Convergence
    2. Mass Balance Table
    3. Min/Max Velocity Table
    4. Force Balance Table
    5. Energy Balance Table
    6. Solution Summary
  2. Extrusion Ratio: Check if the extrusion ratio is correct by checking these aspects of the model:
    • Check the ratio of the inlet to the exit area, which gives an overall measure of how much material deforms during extrusion.
    • If the value of the extrusion ratio is incorrect, inspect the inflow and outflow boundaries in the model to verify and correct them.
  3. License Type: Depending on what problem type you are solving, a basic or advanced license will be checked out.
  4. Model Information: Check the analysis information by verifying these values:
    • Value 0 for Geometry indicates it is a 3D model.
    • Value 0 indicates that the Stokes equations are solved.
    • Value 0 indicates a non-isothermal analysis.
    • Value 1 indicates a steady Simulation.
    The Review Unit system is under the MODEL UNITS section.
    Verify the Model information by confirming the following:
    • The tool material is denoted as Solid material.
    • The extruded material is denoted as Fluid material.
    • In this example, the tool analysis is NOT performed, so the number of solid materials is 0.
    • Check the mesh size and type of elements.
    Note: Most of these data are default values and are seldom modified by the user.
  5. Model Parameters: Verify the Mesh update parameters. To do so:
    • Check if the free surface calculation is performed.
    • Verify other related parameters such as free surfaces, star location, etc.
    Review Material Properties. To do so,
    • Verify the viscosity models employed for the polymer materials.
    • Verify the constitutive model data.
    • Verify how the temperature dependency of viscosity is accounted for.
  6. Reference Quanitities:
    Examine the Energy Equation Data. Work is converted into energy (%), which accounts for viscous dissipation. Check the reference quantities used in the analysis. Verify different parameters used in the numerical solution. To do so,
    • Look at the relaxation parameters used in the solver.
    • Look at the convergence criterion used for the solution variables.
    Note: Most of these data are default values and are seldom modified by the user.
  7. Solution Convergence History:
    Check the Norm of Change in the Solution. The Norm of Change may oscillate initially, but it will decrease steadily after a few initial iteration for all of these solution components: Velocity, pressure, and temperature. The solution is considered 'converged' if the value of the Norm of Change in the Solution is less than the tolerance (0.001) for all of the variables. A slow convergence rate or oscillatory behavior indicates that the mesh is too coarse.

    Note: The plot is created using data in the converge.hist file.
  8. Verification of Mass Balance:
    Check if the Mass Balance is less than 1% to ensure conservation of mass. The Mass Flux table shows mass flow rate across each boundary. A positive sign indicated material entering through the boundary, and a negative sign indicates material leaving the boundary.
  9. Average Velocity:
    The table also shows average velocity of the material entering/leaving through each boundary surface. Note that velocity on a solid wall must be close to zero and velocity on symmetric planes must be equal to 0. Velocity on free surface boundaries must be small - at least a few orders of magnitude less than extrusion speed.
  10. Min/Max Velocities:
    The Profile exit velocity in the extrusion direction must be significantly higher than the velocity in other directions. Velocities in directions other than the extrusion direction indicate the possibility of profile deflection. Velocities at the solid wall must be close to zero.
  11. Verification of Force Balance:
    A positive sign indicates force that is applied on a surface, and a negative sign indicates response The table also contains the average pressure at each boundary surface.

    Check if the average pressure at the inlet is within the acceptable range. Verify the boundary conditions and material properties if the check fails.

  12. Viscous Dissipation:
    The amount of heat generated during deformation should only have up to a 5% divergence from the mechanical work's heat output. The above number can be computed from the pressure on the inlet face, inlet velocity, area of the inlet face, and the % of work converted to heat. Some examples are as follows:
    • P = 10 MPa = 10 e+6 Pa
    • V = 5 mm/s = 0.005 m/s
    • A = 4000.0 mm^2 = 4000e-6 m^2
    • % conversion = 90%
    Heat Generated = 10e+6 X 0.005 X 4000e-6 x 0.9 = 187.55W = 180 W = 0.180 kW. The value of viscous dissipation from the Heat Balance table = 1.81e-1 kW. The difference is less than 5%

View Simulation Results

Review simulation results in the Analysis Explorer.