
This
task shows you how to create a Line Force Density applied to a surface
geometry.
Line Force Densities are intensive loads representing line
traction fields of uniform magnitude applied to curve geometries.
Line Force Density objects belong to Loads objects sets.
The user specifies three components for the direction of
the field, along with a magnitude information. Upon modification of any of
these four values, the line traction vector components and magnitude are
updated based on the last data entry. The line traction vector remains
constant independently of the geometry selection.
Units are line traction units (typically N/m in
SI). 

Line Force Density can be applied to the following types of
supports:
Geometrical Feature 
Mechanical Feature 
Analysis Feature 
Spatial Groups 
Geometrical Groups 
Groups by Neighborhood 
Groups by Boundary 
Others 
Edge 






To know more, refer to Authorized
Supports. 

Open the
sample00.CATAnalysis document from the samples directory.



Click Line Force Density
in the Loads toolbar.
The Line Force Density dialog box appears.


You can change the identifier of the Line Force Density
by editing the Name field.

Set the Axis System.
The Axis System Type combo box allows you
to choose between Global, Implicit and
User Axis systems for entering components of the line traction
field vector:
 Global: if you select the Global Axis
system, the components of the surface traction field will be
interpreted as relative to the fixed global coordinate system.
 Implicit: if you select the Implicit Axis
system, the components of the line traction field will be
interpreted as relative to a local variable coordinate system whose
type depends on the support geometry.
 User: if you select a User Axis
system, the components of the line traction field will be relative
to the specified Axis system. Their interpretation will further
depend on your Axis Type choice.
To select a User Axis system, you
must activate an existing Axis by clicking it in the
specification tree. Its name will then be automatically
displayed in the Current Axis field.
If you choose the User axis system,
the Local orientation combo box further allows you
to choose between Cartesian, Cylindrical
and Spherical local axis orientations.
 Cartesian: the components of the surface
traction field are interpreted as relative to a fixed
rectangular coordinate system aligned with the cartesian
coordinate directions of the Userdefined Axis.
 Cylindrical: the components of the surface
traction field are interpreted as relative to a local
variable rectangular coordinate system aligned with the
cylindrical coordinate directions of each point relative to
the Userdefined Axis.
 Spherical: the components of the surface
traction field are interpreted as relative to a a local
variable rectangular coordinate system aligned with the
spherical coordinate directions of each point relative to the
Userdefined Axis.



 You can define the line traction field direction by using the
compass.
 You can modify the compass orientation either with the mouse or
by editing the compass.
 By applying the compass to any part geometry, you can align the
compass directions with the implicit axis directions of that
geometry: drag the compass by handling the red square and drop it
on the appropriate surface. The normal direction to this surface
defines the new direction. Then, click on the Compass Direction
button to take this new direction into account. You can now invert
the direction if desired, editing the values of the three
components.
 Even if a User axis system has been referenced, the
coordinates of the data mapping stay in the Global axis
system.
Only the User axis system directions are taken into
account with data mapping.


Select the geometry support (an edge) on which the line
traction is to be applied.
Any selectable geometry is highlighted when you pass
the cursor over it.
You can select several supports in sequence, to apply
the Line Force Density to all supports simultaneously.
Symbols representing the Line Force Density are displayed on the
support geometry to visualize the traction field.
As soon as the support is selected, the Select
Mesh Part button is available.
To know more about the Select Mesh Part button, refer to
Selecting Mesh Parts. 

If needed, enter a new value for any one of the four
fields: Norm, X, Y and Z in
the Line Force Density dialog box.
For example, enter below values for the X, Y, Z
components of the line traction field.
The corresponding Norm value is automatically
computed and displayed.
 The remaining three fields are automatically computed and
displayed.
 The visualized symbols orientation is also updated to reflect
the modification.


You can reuse data (Data
Mapping) that are external from this version (experimental data
or data coming from inhouse codes or procedures). For more details,
refer to Data Mapping (only available
if you installed the ELFINI Structural Analysis product). 

Click OK.
A Line Force Density object appears in the
features tree under the active Loads objects set.



 You can either select the edge and then set the Line Force Density
specifications, or set the Line Force Density specifications and then
select the edge.
 If you select other surfaces, you can create as many Line Force
Density loads as desired with the same dialog box. A series of Line Force
Densities can therefore be created quickly.
 Loads are required for Stress Analysis computations.
 If several Analysis Cases have been defined in the Finite Element
Model, you must activate a Loads objects set in the specification tree
before creating s Line Force Density object (only available if you
installed the ELFINI Structural Analysis product).
 Line Force Density objects can be edited by a double click on the
corresponding object or icon in the specification tree.


The ELFINI Structural Analysis product offers the
following additional functionalities:

Contextual menu on the load object:
 Line Load Visualization on Mesh: the translation
of your Distributed Force object specifications into solver
specifications can be visualized symbolically at the impacted mesh
nodes, provided the mesh has been previously generated using a mesh
only computation.
To know more, refer to Visualizing
Loads on Mesh.

Contextual menus on the loads set:
 Generate Image: generates an image of the computed load
objects (along with translating all userdefined Loads specs into
explicit solver commands on mesh entities), by generating symbols for
the elementary loads imposed by the Loads objects set. The image can be
edited to include part or all of the options available.
To know more, refer
to Generating Images.
 Report: the partial status and results of intermediate
preprocessor computations are reported in HTML format. It represents a
subset of the global report capability and generates a partial report
of the loads objects set Computation.
To know more, refer to Generating
Reports.
 Selfbalancing: refer to
Creating Pressures.

