3.13 Loads Section

The Loads section defines all nodal, edge, surface, and body loads that can be applied to the model.

Nodal Loads

Nodal loads are applied by the _nodal_load element. The nodal load is defined by the type _attribute.

Example:

<nodal_load type="nodal_load" node_set="set1">
  <dof>x</dof>
  <scale lc="1">1.0</scale>
</nodal_load>

Surface Loads

A surface load can be applied using the surface_load element. This element takes two attributes, namely type, which defines the type of surface load that will be applied, and_ surface _which defines the surface that this load will be applied to.

Example:

<surface_load type="pressure" surface="surface1">
  <pressure lc="1">1.0</pressure>
  <symmetric_stiffness>0</symmetric_stiffness>
</surface_load>

Body Loads

A body load can be used to define a source term to the model. The following sections define the different type of body loads that can be applied. In the case of body forces, these body loads represent the body force per mass, \(\mathbf{b}\), which appears in the momentum balance as

\[ \rho\mathbf{a}=\divg\boldsymbol{\sigma}+\rho\mathbf{b}\,, \]

where \(\rho\) is the mass density, \(\mathbf{a}\) is the acceleration (set to zero in quasi-static analyses), and \(\boldsymbol{\sigma}\) is the Cauchy stress tensor.

Example:

<body_load type="const">
  <x lc="1">1.0</x>
  <y lc="2">1.0</y>
  <z lc="3">1.0</z>
</body_load>

The lc attribute defines the load curve to use for the corresponding component. The values of the components can be used to define scale factors for the load values.