Dealing with the new entities Constraints

Dealing with the new entity Constraints


This article explains the changes applied to kinematic and distributed couplings from HyperWorks 2022. Please have a look at this article if you want to get a complete overview of Abaqus changes from version 2022.


Why are couplings now considered as Constraints?


For a long time Abaqus couplings, as Radioss rigid bodies, LS Dyna *CONSTRAINED… were considered as elements in HyperMesh, despite they are not elements from a solver point of view.

This brought some benefits, such as the capability to ensure the connectivity between components. But it also came with some misuse, and frequently users could populate/maintain coupling with free nodes after some modification, which led to extra validation steps.

Plus, to bring consistency with explicit solver profiles, we are re-designing the Connectivity check so that it allows to consider for implicit solvers not only the Constraints, but also some other entities such as tied contacts (which were not supported in the past).  

As we will eventually merge Components with Parts, we are not considering anymore these rigid entities as components, and we have migrated them to a new entity type called Constraint, starting with Abaqus couplings from version 2022.

This brings some modifications in their usage, that are listed in the frequently asked questions below.


I cannot find entities attached to my constraints anymore. How to check connectivity of my model then?


For implicit codes, model checker must be used for checking the model's connectivity up to version 2022.2. 

From version 2022.3, the Find Attached (can be reached through SHIFT + F5) will include an option to detect attached components even if they are attached through a Constraint.


For explicit codes, you can rely on the “Find connectivity” tool available in the Validate ribbon:



What is the preferred way to create my kinematic couplings?


This depends on what you are trying to model. If your couplings are intended to be part of a connection between several parts (spotwelds, fasteners), then it is better to look for connectors, and to look for the more appropriate connection type.

For instance, constraints are frequently used for fasteners.


For other cases, the preferred way right now is to use the Rigid icon from the Model ribbon, especially if you want or need to primary node to be computed automatically.

For some profiles such as Abaqus, this tool still redirects you to the hisctorical panel.

In the coming versions, the panel will be replaced by a context, which is already available in 2022.2 for some profiles such as OptiStruct:


I cannot group anymore all my constraints inside a unique container. How to get a simplified view in the browser?


Constraints are part of a larger initiative, whose intent is to bring in HyperMesh more engineering oriented entities, instead of the generic collectors which were considered for years as not consistent because they were grouping entities with different solver types. E.g., groups were grouping contacts, rigid walls, sections, …

These new entities will also help improve our conversion process across the different solver profiles.

As a first consequence, the content exposed in the model browser as it was exposed in 2017 will increase significantly, which is why we decided to propose a new organization of the model browser, turning it into a synthesis of the model instead of an exhaustive list of all entities.



2017-like browser                                                  New synthesis model browser


As we got several users requesting for the old-style browser, we bring back the possibility to use it through a preference.

That said, the more new entities we bring in, the more cumbersome old-style browser will become.

Thus, the new browser showing synthesis is recommended for performance and ease of use of the model.

Then when you double click on constraints, a new tab is open, where you retrieve only your constraints.

You can customize the columns displayed, e.g., by adding dof 1 to 6, and you can perform bulk changes on the fly:

Up to version 2022.2, constraints coming from an Abaqus legacy model are exposed with an internal HyperMesh name. From version 2022.3, the constraint name will contain as a prefix the name of the former component, so that you can filter them by name in the Constraint Browser.


How can I review my constraints?


If you want to do the same as in the legacy interface (show, hide, isolate), you can use either the Constraint browser, or the idle bar top left in the graphic area and hide/show/isolate some constraints.


What if I want to review the constraints associated to displayed components/parts?


When you show some specific components/parts in the graphic area, you may want to show only the Constraints which are related to your displayed parts. Form 2022.3, you can use Find Attached to review them.


I cannot mirror my constraints anymore. How can I save time for creating constraints for symmetric assemblies?


As stated earlier, if the primary purpose of your couplings is to connect parts together, please use Connectors. This is the must-go technology for such modeling purpose, and latest version even allows to instance connectors. With the help of connector instances, you will not need to mirror your entities as you will synchronize the instances together.

For other purposes, please contact us so that we can understand your use cases and see how to integrate back this feature in a future version of HyperMesh.


How can I edit the nodes of my constraints?


As we are getting closer to the solver definition of these entities, we are creating and exposing the node set when setting up the coupling.

The quickest process now for editing the entities belonging to your constraint is to go into the browser, then right click -> Edit in the empty space left to the set name to update your selection.



I have updated my mesh (rebuild, delete elements, ..) but my set is not updated. How to proceed?


First please make sure the preference Auto update sets on mesh change is checked:

If the set is still not updated properly, please:


I am still using the old interface or HyperMesh. How do I show/hide constraints?


You can show/hide Constraints and edit their attributes from the Model browser.

The creation can be done either from Connectors for connecting parts together, or from panel
1D -> rigids otherwise.

Please note the Connectivity check will not be updated in the legacy interface.


I cannot see anymore my couplings when post-processing my results in HyperView. How can I get them back?


HyperView does not yet support Constraints review when loading the inp file as model file. Then, short term, you must load only the odb file as both model and result file to see constraints in HyperView.

Or, for quick post-processing purposes, you can also look at the Post ribbon in HyperMesh client, where we brought back several capabilities for post-processing implicit results.