How to Add Line Elements

When setting up a model for analysis, you may want to add line elements for simulating conditions such as the following:

• spring supports;
• bolted connections;
• moment or torque loads on solid elements;
• motion response including the effect of actuators, dashpots or sliders in a Mechanical Event Simulation (MES); or
• first-pass analysis of a structure.

As an alternative to using the Superdraw III precision model-building tool, you can add line elements in the FEA Editor environment of FEMPRO. Use the "Geometry:Add Lines..." command sequence to access the "Define Geometry" dialog (see Figure 1). (Or, click on the "Create Lines" icon in the "Geometry" toolbar.)

Figure 1: The "Define Geometry" dialog can be used to add lines in an FEA model.

The part, surface and layer number for the lines can be specified in the "Attributes" section. The beginning coordinate for the line can be specified in three ways:

• In the "ID:" field of the "Vertex" section, enter the vertex ID where you want to begin the line. You can place the cursor over a vertex in the display window and a pop-up message will appear with information about the vertex including its ID number and coordinates. (See Figure 2.)

Figure 2: By placing the cursor over a vertex, a pop-up window appears with information including the vertex ID number.

• Enter the coordinates in the "X:", "Y:" and "Z:" fields of the "Vertex" section.
• Position the cursor over a vertex in the display window and click.

Define the second endpoint of the line using any of the three methods described above. If the "Use Relative" checkbox is activated, values can be entered in the "DX:", "DY:" and "DZ:" fields to specify the relative distance from the original vertex. If the "Single Line" checkbox is activated, only one line is created; if it is not activated, you can add multiple lines in a continuous chain.

The newly created line elements will be added to the model tree. You can then specify finite element data for the part(s) containing the line elements including the element type (see Figure 3).

Figure 3: In the model tree, the element type for the line elements can be specified.

The following element types are available:

• Linear: beam, gap/cable, rigid, spring and truss elements
• Nonlinear: actuator, beam, contact, coupling, dashpot, general contact, pipe, slider and truss elements
• Heat transfer: rod elements

Thus, the capability to add line elements in FEMPRO provides flexibility for model building, particularly when working with CAD-generated models. It also enables you to create line element models entirely within FEMPRO.

For more information about adding line elements in FEMPRO, see the ALGOR User's Guide.