For all circuit analyses, you first need to build a circuit model using the CIRCU124, CIRCU125, TRANS126, COMBIN14, COMBIN39, and MASS21 elements. The preferred method for building the circuit is to use the Circuit Builder, an interactive builder available in the Mechanical APDL graphical user interface (GUI). The Circuit Builder performs the tasks listed below:
Enables you to select circuit components and place them at the desired location in the circuit with the help of a mouse
Creates a model of the circuit interactively
Assigns "real" constants to circuit components and allows you to edit them
Assigns excitation to independent sources
Verifies excitation graphically
Provides an interactive connection to the FEA domain
Lets you specify source loads for voltage and current source components.
The Circuit Builder establishes the element types, real constants, and node and element definitions. It sets up multiple element types, one for each circuit element. As with any other GUI feature, the Circuit Builder writes to the log file all the commands used to create the circuit elements.
The GUI offers a special "wire element" option. This option is provided as a convenience tool to connect regions of an electrical circuit with a "wire." The wire represents a short circuit (infinite conductivity) between the two connection points. A MESH200 element is created for visualization purposes only. The end nodes of the wire are coupled together (using the CP command) to represent the short circuit. If two or more wire elements are connected together, the nodes of these wire elements are all coupled together in one node coupling set with the VOLT degree of freedom. Deleting any one of these wire elements will force an automatic deletion of all the connected wire elements, the node coupling set, and any node that is not attached to a non-wire element.
To build a circuit, activate the Mechanical APDL GUI and use the procedure described below. These additional tips also may help you:
To set an initial focus and distance in the GUI consistent with the circuit icon size, issue the Circuit Builder's "Center WP" option. To do so, choose . When the "Center WP" option is issued, the WP Settings dialog box will appear as a convenience for turning the working plane grid on or off, adjusting the snap increments, etc.
To scale the circuit icons or change the width of the circuit lines, issue the Circuit Builder's "Scale Icon" option. To do so, choose .
Consider displaying two windows: one for the circuit and the other for your model.
Remember to ground the circuit at one node. To do so, either choose or issue the D command with the VOLT label.
Choose menu path . The Preferences dialog box appears.
Choose "Electromagnetic" if you are planning to do a circuit-coupled electromagnetic analysis. Choose "Electric" if you are just running a circuit analysis.
Choose . In the dialog box that appears, specify a jobname for your analysis and click on OK.
Choose . In the dialog box that appears, specify a title for your analysis and click on OK.
Choose .
If you need to locate the circuit away from an existing finite element model (for instance, if you are doing a coupled electromagnetic-circuit analysis), use the WorkPlane option on the Utility Menu to move the working plane origin to the location where you want to start the circuit. (Otherwise, skip this step.) The location of the circuit can be arbitrary and does not affect the analysis results. For convenience, you can center the working plane origin in the Graphics Window by choosing .
Choose the circuit component you want from the Circuit Menu and follow the prompts shown in the Input Window. Most choices display the "picker" you use to locate the I and J nodes of the element and then position the circuit component by picking an offset location from the I-J line. The length of each circuit element, and the element's location relative to other circuit elements, can be arbitrary and does not affect analysis results. Once you have picked all necessary locations, a dialog box appears requesting an ID number (element number) and real constants to identify the component. If the icon size is too small, or the circuit lines to thin, you can make adjustments by choosing .
After building the circuit, verify it and modify the data if necessary. The menu choice allows you to plot and verify the wave form of any input loads. Another menu choice, , allows you to check and modify the real constants of any circuit component. To delete specific circuit components, choose .
The Circuit Builder is the most convenient way to construct a circuit. However, you can also build a circuit by individually defining each node, element type, element, and real constant.
Once you have built the circuit, you are ready to perform a static, harmonic, or transient analysis (the source determines the type of analysis).