About loads

External loading can be applied in the following forms:

  • Concentrated or distributed tractions.

  • Concentrated or distributed fluxes.

  • Incident wave loads.

Many types of distributed loads are provided; they depend on the element type and are described in About the element library. This section discusses general concepts that apply to all types of loading; see About Prescribed Conditions for general information that applies to all types of prescribed conditions.

Concentrated and distributed tractions are discussed in Concentrated loads and Distributed loads, respectively. Thermal loading (heat flux) is discussed in Thermal loads. Electromagnetic loads are discussed in Electromagnetic loads. Loads due to incident wave fields such as due to sound sources or an underwater explosion are discussed in Acoustic and shock loads. Pore fluid flow is discussed in Pore fluid flow. All other load types, which are applicable to only a single type of analysis, are discussed in the appropriate sections in Analysis Procedures and Analysis Solution and Control.

In some situations, concentrated loads and some commonly used distributed loads (such as pressure applied on a surface) may rotate during a geometrically nonlinear analysis. Such loads are known as follower loads; further details on follower loads can be found in Follower loads in large-displacement analysis, Specifying concentrated follower forces, Follower surface loads, and Follower edge and line loads. Follower loads may also lead to an unsymmetric contribution to the stiffness matrix, which is generally referred to as the load stiffness; some issues related to the load stiffness contribution are discussed in Improving the rate of convergence in large-displacement implicit analysis and Improving the rate of convergence in large-displacement implicit analysis.

The following topics are discussed:

Related Topics
About Prescribed Conditions
Concentrated loads
Distributed loads
Thermal loads
Electromagnetic loads
Acoustic and shock loads
Pore fluid flow
In Other Guides
General and perturbation procedures
Creating and modifying prescribed conditions
Using the load editors