About Assembled Fasteners

The assembled fastener construct lets you efficiently assign complex fastener behaviors in a large number of point fasteners.

You define a connector that joins several layers, and specify the interaction between the fastener and the joined material for each layer. Using assembled fasteners, you can define connector and constraint behaviors once and apply these to multiple point fasteners in your model.

The following topics are discussed:

This page discusses:

See Also
Defining Point Fasteners
In Other Guides
Mesh-Independent Fasteners

The Assembled Fastener Construct

Assembled fasteners are a type of point fastener. With point fasteners, you specify locations by picking points. These points are projected onto the layers included in the fastener definition. With assembled fasteners, you have finer control of the fastener behavior at each layer.

The figure below shows the parts of a typical assembled fastener. For illustration purposes, the image shows a single intermediate layer; however, you can define assembled fasteners for up to 10 layers. These layers can be either shell or continuum sections, or they can be a combination of both.

Node on the surface that is used for the connection. This node is the node nearest to the projection of the placement point onto the layer.
Tension connector between layers.
Optional connector for shear elasticity (actual connector has a length of zero).
Optional top/bottom tension connector.
Optional pre-tension section (actual section has a length of zero).

Assembled Fastener Behaviors

You have several options to specify the fastener behavior for both the outer and inner layers of the stack that the fastener joins.

Tension Configuration

The following types of tension configurations are available:

Configuration Description
Drill through The layers are joined by a series of chained connections.
Bottom/top The top and bottom layers are joined directly, while the connections from one layer to another are done in a piecewise manner.
Bottom/top + drill through The top and bottom layers are joined directly, and the layers are joined by a series of chained connections.

Tension Connector Type

You can specify the following behaviors for the tension connectors:

Type Description
Bushing Models the connectors as bushings. You can define axial, shear, torsional, and bending stiffnesses.
Cartesian Allows relative displacement of the end points in three directions. You can define axial and shear stiffnesses.
Axial Allows relative displacement of the end points along the line that connects them. You can define axial stiffness only.

Pre-tension

You can define a pre-tension force on the connector. For more information, see Modeling a Fastener with Truss or Beam Elements.

Clearance

You can define clearance behavior for the fastener, which allows you to specify additional elastic behavior between the fastener and the joined surfaces. You can apply this clearance behavior to all surfaces or to the middle surfaces only.