Creating discrete fasteners

You can create discrete fasteners in the Interaction module by selecting the attachment lines that connect the desired surfaces. For each attachment line, Abaqus/CAE determines the fastening points and applies a distributing coupling between the fastening points and their corresponding surfaces.

See Also
About fasteners
Understanding attachment points and lines
In Other Guides
Coupling Constraints

Context:

You must assign a connector section to each attachment line that you select. You can use any of the Abaqus connection types to model complex behavior of your fasteners, such as deformable connectors that include the effects of elasticity, damage, plasticity, and friction. In addition, you can assign different connector sections to different attachment lines.

  1. From the main menu in the Interaction module, select Special Fasteners Create .

    Abaqus/CAE displays the Create Fasteners dialog box.

    Tip: You can also create discrete fasteners using the tool in the Interaction module toolbox.

  2. From the Create Fasteners dialog box that appears, select Discrete fasteners and click Continue.
  3. Select the attachment lines that represent the location of the discrete fasteners, and click Done. For more information, see Creating attachment lines by projecting points.

    Abaqus/CAE displays the Edit Fasteners dialog box.

  4. Choose the method to couple the motion of the fastening points to the average motion of the nodes on the surfaces that fall inside the influence radius.

    • Choose the Coupling type option Continuum distributing (default) to use a general-purpose distributed coupling scheme or Structural distributing to augment the distributed coupling scheme to account for rotations of surface nodes such that a fastening point remains approximately on a shell surface on bending.

    • Choose the Rotational Coupling type option Rotational Continuum distributing or Rotational Structural distributing (default).

    For more information, see Distributing Coupling Constraints.

  5. If desired, toggle off a rotational degree of freedom to remove its constraint. Abaqus/CAE always constrains all translational degrees of freedom in a distributing coupling.
  6. Choose the weighting method that Abaqus will use to modify the default weight distribution at the coupling nodes:

    • Choose Uniform (default) to select a weight distribution that is uniform and equal to 1.0.

    • Choose Linear to select a weight distribution that decreases linearly with distance from the fastening point.

    • Choose Quadratic to select a weight distribution that decreases by a quadratic polynomial function with distance from the fastening point.

    • Choose Cubic to select a weight distribution that decreases by a cubic polynomial monotonic function with distance from the fastening point.

    For more information, see Weighting Methods.

  7. If desired, select or create a datum coordinate system that specifies the initial orientation of the local system in which the constrained degrees of freedom are defined. By default, the orientation of the constrained degrees of freedom is defined by the global coordinate system.
  8. Specify the radius of influence centered about the fastening point. You can enter a value or allow Abaqus to use the entire surface to define the coupling constraint.
  9. Click OK to close the Edit Fasteners dialog box.

    Abaqus/CAE displays the distributing coupling of the discrete fastener between the fastening points and connected faces. The radius of the circle reflects the specified radius of influence. If the coupling constraint definition uses the entire surface, the lines from the fastening point will extend past the circle. For orphan mesh models, you can modify the appearance of the distributing coupling by changing the face and edge density in the assembly display options; for more information, see Controlling the display of attributes.

  10. Complete the discrete fastener definition by assigning a connector section to the attachment lines, as described in Creating and modifying connector section assignments.

    Abaqus/CAE displays the connector symbols for the discrete fastener.