Defining Assembled Fasteners

You can use the assembled fastener construct to define complex behavior with point fasteners.

This task shows you how to:

See Also
About Assembled Fasteners

Create the Fastener

  1. From the Connections section of the action bar, click Point Fastener .
  2. From the Engineering connection options, select one of the following:
    OptionDescription
    Default Automatically creates a free engineering connection or selects the existing engineering connection if there is only one.
    Select existing Allows you to pick an existing engineering connection from a list.

    Note: If you select an existing connection, you must choose a support from the part instances used when the engineering connection was created.

  3. Optional: Enter a descriptive Name.
  4. Select the geometric or mesh Parts to be fastened.

    Tip: You can click to clip the selection area to show only the smallest part, which can make it easier to pick the more detailed Fastener placement geometry you need. After you activate the clipping box, you can click to drag the box edges to resize it.

  5. Optional: To load fastener properties from a saved template file:
    1. Click .
      The Object Selection dialog box appears.
    2. Select one of the following options:

      • Search the available templates stored in the database, and select the template.
      • Click Import a file to import a file stored on your computer, and click the check mark in the object selection prompt that appears after the document has been imported.

    The parameters are applied to the current fastener definition.
  6. Optional: Click to save the parameters of the current fastener to a reusable template document, and specify a name for the document. For more information, see Template Files.
  7. Select the fastener Material.
  8. Enter the Fastener diameter; for example, the diameter of a bolt or rivet.

    The fastener diameter defines the radial influence distance from the center point of the fastener on each of the connected surfaces. If any portion of a mesh element lies within the radius, all nodes of the element are connected by the fastener.

    Note: The fastener diameter is required only for Solid hex fasteners. If you enter a diameter for other construct types, this diameter is used to calculate the default influence radius. You can also specify the influence radius directly in the Realization options, as described below.

Define Fastener Placement

  1. Specify the Fastener placement method:
    OptionDescription:
    Select points

    Uses points or vertices to define the fastener locations. The selected points must be within reasonable proximity of the fastener placement—along or between the bodies being connected by the fastener. The app projects the positioning points onto the target surfaces along the surface normal vectors.

    Warning: There are no restrictions on the points that you can select to create the fastener. However, if you select an inappropriate point, the connection is likely to fail during or before simulation.
    Along lines

    Uses a line or edge to define the fastener placement. For example, you can use this method to distribute a number of spot welds along a line. The app distributes the fastener locations at equally spaced intervals along the placement line.

    Specify coordinates Uses X-, Y-, and Z-coordinates, which you enter directly or import, to locate the fasteners. For more information, see Specifying Coordinates for Point Fasteners.

    You can also select a geometric set containing points and curves to define the fastener placement.

  2. If you selected to define the fasteners Along lines, do the following:
    1. Specify the Clearance, which is the distance applied at the beginning and end of the line before the fastener points are placed.

      The first fastener point is located at this distance from one end.

    2. Specify the Distribution method, which determines where the fasteners are located along the line. You can specify either the Number of fasteners to be placed along the line or the Fastener spacing (distance between consecutive fasteners) along the line. For example, if you specify a 20 mm line with a clearance of 0 and 10 fasteners, the app places fasteners at each end point and distributes 8 fasteners equally between the two end points.

Define the Assembled Fastener Construct

  1. Set the fastener Construct type to Assembled.
  2. Optional: Choose the stacking direction:
    1. Toggle the Top support/ Bottom support control to choose which surface you want to define the stacking order in relation to.
    2. Use the dropdown list to specify which part represents the top or bottom.

    If you do not specify the stacking direction, the app determines a direction based on the picked supports.

  3. Set the Tension configurationto one of the following: Drill through, Bottom/top, or Bottom/top + drill through.

    For more information, see Assembled Fastener Behaviors.

    The schematic in the dialog box updates to show the selected tension configuration.
  4. Set the tension connector Type to one of the following:Bushing, Cartesian, or Axial.

    For more information, see Assembled Fastener Behaviors.

  5. Define the stiffness values for the components included in the chosen tension connector type.
  6. Optional: Select Enable advanced behaviors, and click . With this option, you can define additional connection behaviors. See Connection Properties for more information.
  7. Optional: Select Include pretension.
    A pre-tension section is added to the fastener. The schematic indicates the added section.
  8. If the tension configuration is Bottom/top or Bottom/top + drill through, enter the value for Bottom/top elasticity.
  9. Optional: Select Include clearance.
    1. Specify whether to include All layers or only the Middle layers.
    2. Specify a value for the Shear elasticity.
  10. Optional: Choose an edge or a publication to define the Axis-2 orientation.

Specify the Realization Options

  1. From the Coupling type options, select one of the following:
    OptionDescription
    Kinematic Couples edge or face supports directly to the motion of a reference point.
    Continuum distributing Couples the displacement and rotation of the fastening points to the average displacement of the nodes.
    Structural distributing Couples the displacement and rotation of the fastening points to the average displacement and rotation of the nodes.
  2. From the Weighting method options, select one of the following:
    OptionDescription
    Uniform Maintains an equal weight factor on all nodes within the influence radius.
    Linear Decreases the weight factor linearly with the distance from the fastening point.
    Quadratic Decreases the weight factor by a quadratic polynomial function of the distance from the fastening point.
    Cubic Decreases the weight factor by a cubic polynomial monotonic function of the distance from the fastening point.
    Tied Weights each node based on the shape of the mesh element face that contains the projected location.
  3. From the Coupled faces options, select one of the following:
    OptionDescription
    Nearest Limits the coupling to the nodes in the element containing the projected location.
    Within the radius Includes elements within the specified radius surrounding the projected location. The default is half the fastener diameter. This option is not available with the Tied weighting method.

    This option determines which element faces are included in the coupling. The coupling uses all the nodes in the included element faces.

  4. Enter the value for Maximum projection distance, which is the Maximum gap (distance) between the bodies bridged by a fastener. The fastener is not created at a point if the bodies are farther apart.
  5. Enter the value for Maximum angle, which is the limit for the angle of inclination between the two surfaces being fastened. The fastener is not created at a point if the angle of inclination at that point exceeds this value.
  6. Enter the value for Maximum angle between adjacent faces, which is the limit for the angle between the normals of adjacent faces. The fastener is not created at a point if the angle is exceeded.
  7. Enter the value for Adjust tolerance, which allows the simulation to move the center of the fastener by a specified distance when projecting the positioning point onto the surface being connected.

    Adding a small tolerance can help avoid problems when the fastener point is very close to a hole in the surface (for example, on a flange) or even inside the hole. With the default tolerance of zero in this case, the projection of the positioning point might fail. Increasing the tolerance value allows the simulation to move the center of the fastener slightly so that the point projection avoids the hole.

  8. Optional: Click Update Mesh to see the mesh created for the point fastener.
  9. Click OK.