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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).
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Line Force Density can be applied to the following types of Supports:
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This task shows you how to
create a Line Force Density applied to a surface geometry.
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You can use the sample00.CATAnalysis
document from the samples directory
for this task:
Finite Element Model containing a Static Analysis Case and computed corresponding Static
Solution.
Before You Begin:
Go to View -> Render Style -> Customize View and make
sure the Shading, Outlines and Materials options are
active in the Custom View Modes dialog box.
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1. Click the Line Force Density icon 
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The Line Force Density dialog box is displayed.
2. You can change the identifier of the Line
Force Density by editing the Name field.
3. 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 User-defined 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 User-defined 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 User-defined Axis. |
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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.
4. 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.
5. 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 re-use data (Data
Mapping) that are external from this version (experimental
data or data coming from in-house codes or procedures). For more
details, see Creating Pressures (only available if you installed the ELFINI Structural Analysis
product).
6. Click OK in the Line Force Density dialog box
to
create the Line Force Density.
A Line Force Density object appears in the features tree under the active
Loads objects set.
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| 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. |
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Make sure the computation is finished before
starting any of the below operations. |
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Products
Available in
Analysis Workbench
The ELFINI Structural Analysis
product offers the following additional features with a right mouse click
(key 3):
| on a Line Force Density object: |
Line load visualization on mesh: the translation of
your Line Force Density object specifications into solver
specifications can be visualized symbolically at the impacted mesh
elements, provided the mesh has been previously generated via a
Compute action.
| on a Loads objects set:
1) Generate Image: generates an image of the computed Load objects
(along with translating all user-defined 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.
2) Report: the partial status and results of intermediate
pre-processor 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.
See Creating Pressures for more details.
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3) Double-clicking on the Loads set, you will display the
Loads dialog box that lets you choose whether you wish to apply
self-balancing to the load. Example of use: if this option is used with
iso-static specifications, it will allow you to simulate free-body
loading. If you make the option active, the center of inertia results
null.
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