27.4.2 Concentrated loads

Products: ABAQUS/Standard ABAQUS/Explicit ABAQUS/CAE

References

Overview

Concentrated loads:

apply concentrated forces and moments to nodal degrees of freedom; and
either are fixed in direction or rotate as the node rotates.

In steady-state dynamic analysis both real and imaginary concentrated loads can be applied (see “Direct-solution steady-state dynamic analysis,” Section 6.3.4, and “Mode-based steady-state dynamic analysis,” Section 6.3.8, for details).

Multiple concentrated load cases can be defined in random response analysis (see “Random response analysis,” Section 6.3.11, for details).

Concentrated loads are also used to apply the pressure-conjugate at nodes with pressure degree of freedom in acoustic analysis. See “Acoustic loads,” Section 27.4.5.

Actuation loads in connector elements can be defined as connector loads, applied similarly to concentrated loads. See “Connector actuation,” Section 25.1.3, for more detailed information.

The procedures in which these loads can be used are outlined in “Prescribed conditions: overview,” Section 27.1.1. See “Applying loads: overview,” Section 27.4.1, for general information that applies to all types of loading.

Concentrated loads

Concentrated forces or moments can be applied at any nodal degree of freedom.

You should not apply a moment load at the origin of a cylindrical coordinate system; doing so would make the radial and tangential loads indeterminate.

Input File Usage:

*CLOAD

ABAQUS/CAE Usage:

Load module: Create Load: choose Mechanical for the Category and Concentrated force, Moment, or Generalized plane strain for the Types for Selected Step

Specifying concentrated follower forces

You can specify that the direction of a concentrated force should rotate with the node to which it is applied. This specification should be used only in large-displacement analysis and can be used only at nodes with active rotational degrees of freedom (such as the nodes of beam and shell elements or, in ABAQUS/Explicit, tie nodes on a rigid body). If you specify follower forces, the components of the concentrated force must be specified with respect to the reference configuration.

Input File Usage:

*CLOAD, FOLLOWER

ABAQUS/CAE Usage:

Load module: Create Load: choose Mechanical for the Category and Concentrated force, Moment, or Generalized plane strain for the Types for Selected Step: Follow nodal rotation

Defining time-dependent concentrated loads

The prescribed magnitude of a concentrated load can vary with time during a step according to an amplitude definition, as described in “Prescribed conditions: overview,” Section 27.1.1. If different variations are needed for different loads, each load can refer to its own amplitude.

Modifying concentrated loads

Concentrated loads can be added, modified, or removed as described in “Applying loads: overview,” Section 27.4.1.

Improving the rate of convergence in large-displacement implicit analysis

When concentrated follower forces are specified in static and dynamic analysis, the unsymmetric matrix storage and solution scheme should normally be used. See “Procedures: overview,” Section 6.1.1, for more information on the unsymmetric matrix storage and solution scheme.