Note: Many types of loads and constraints (such as nodal, surface, and edge constraints; temperatures, displacements, and velocities) are used within different analysis types. Where the application of a load or constraint is essentially the same among the various analyses, that load or constraint is discussed within this section of the program Help. Where minor, analysis-specific differences exist, they will also be addressed here. Where major differences exist between the implementation of loads or constraints for specific analysis types, these will be covered within the analysis-specific branches of the program Help. For convenience, links will be provided to direct you to analysis-specific load and constraint pages.
General Considerations:
- Loads and constraints are added to the model within the FEA Editor environment. They can be applied to vertices, edges, lines, surfaces, or parts; depending upon the type of load or constraint, analysis type, and/or element type. Typically, you first select one or more entities of the same type. Then, choose the appropriate ribbon command, or right-click and add the desired load or constraint via the context menu that appears. It is also possible to invoke a load or constraint command from the ribbon prior to selecting the entities to which it will be applied. Either workflow is supported.
- Some loads can be applied to a model based on results from another analysis. In such cases, certain loads require the mesh to be identical in the two models, and other loads allow the mesh to be different between the two models. Refer to the respective load page to see the requirements.
- Nonlinear and transient analyses use load curves to control the magnitude of applied loads as a function of time. For information regarding this, refer to the documentation for the specific analysis type.
- Some loads can be applied to a model based on results from another analysis. Some loads require the mesh to be identical in the two models. Other loads allow the mesh to be different in the two models. Refer to the respective load page to see the requirements.
Application of Loads and Constraints at Duplicate Vertices
The FEA Editor always keeps separate vertices (duplicate vertices) at the boundaries between different parts. Two or more vertices exist at the same coordinate – one for each part. If duplicate vertices are selected (such as with a rectangle drawn around the nodes on both adjacent parts) and a nodal load or constraint is added, the duplicate vertices are treated as follows:
- The count of selected vertices in the title bar includes the duplicate vertices.
- The load or constraint is applied at all vertices, including the duplicates. If this is not appropriate, then hide the other parts before selecting the vertices.
- If the parts have some type of bonding at the node, then both duplicate loads will be applied to the one node that is created when the Check Model or analysis is performed.
- If the parts have some type of contact, the duplicate vertices will create two nodes, each with one load.
If the type of contact is changed after the nodal load or constraint is applied, then the load or constraint at the common vertices should be inspected for proper behavior and re-done if necessary. Duplicate loads or missing loads can occur, depending on the situation.
If using the point selection method at a duplicate vertex and the intent is to pick only one of the vertices, it is suggested to hide all other parts except for the one that is to be loaded or constrained.