Parts are made up of one or more bodies. As a result, when working with model systems, the application treats meshed parts and meshed bodies differently with regards to whether the mesh is transferred to the downstream system. Bodies meshed in an upstream system always transfer the mesh to the downstream system. However, parts (single-body or multi-body) meshed and suppressed later in an upstream system; do not have their mesh transferred to the downstream system during assembly. Consequently, when the downstream system supports unsuppression (Mesh object Read Only property set to No), any unsuppressed parts require you to generate a new mesh (unlike an unsuppressed body). This is a different behavior compared to transferring a single model. The application transfers the mesh of a suppressed part for a single model and enables you to unsuppress parts without generating a new mesh.

The application does not support Mesh Edit features, such as Mesh Connections, Node Merge, etc. in the assembled system if the Read-Only property on the Mesh object in the assembled system is set to Yes and if at least one of the upstream systems includes mesh edits.

Don't lose scoping: Geometry from External Model (.cdb) files is partially associative. When you have geometry from multiple External Model system assembled, and you refresh upstream model data into the downstream system, any geometry scoping that you have performed on an object in the downstream analysis will be lost for the modified External Model system only. That is, only External Model systems that you change lose scoping. For example, if you have two External Model systems assembled, System 1 and System 2, and you have objects scoped to geometry in the assembled system. If you modify System 1 and then refresh the upstream system, geometry scoping on objects is lost only for System 1. System 2 experiences no scoping losses. A more robust way to maintain scoping is to properly define imported Named Selections or criterion-based Named Selections.

In addition, if you are using the Inventor application, Autodesk Inventor, any changes you make in the application will cause the loss of scoping in the downstream Mechanical system following an update.

The Geometry object property Scale Factor Value, allows you to modify the size of imported geometries in the upstream systems. The scale factor value of newly imported geometries is 1.0. You can modify the value and that modified value is expected to be preserved on updated models.

Be aware that when you assemble models and change the associated unit of measure, you are limited by a scale factor limit of 1e-3 to 1e3. This scale factor limit is the limit for any combination of models. Factor values are totaled and anything outside of this range is ignored. As a result, due to these tolerances, scaled models, especially larger and/or combined models, sometimes have problems importing geometry/mesh.

You need to perform material assignment in the upstream systems. The Material category property, Assignment, in the downstream system is read-only.

For Named Selections, Mechanical sends only 32 characters to the Mechanical APDL application input file.

The use of Based on System Name or User Specified Tag options for the Object Renaming property can easily generate names which are same for the first 32 characters and therefore cause Named Selections created later in the process to overwrite earlier ones. The application issues a warning if this scenario is detected during the solution process.

Note that this limitation only affects the use of Named Selections in a Commands object.

For all other objects scoped to named selections, the length of named selection has no bearing on the scoping.

When you assemble rigid body systems or systems that include rigid bodies, Mechanical may require you to remesh the rigid bodies if the application detects new contact conditions on the rigid bodies. If this is the case, the application sets the Read Only property on the Mesh object to No and also cleans any imported mesh-based Named Selections. These objects need to be re-scoped. The Mesh object property, Read Only is set to No when importing rigid bodies or rigid body systems from Mechanical Model and/or analysis systems. Note that it is not possible to remesh (Read Only cannot be set to No) when assembling upstream sources from External Model or ACP, so contact conditions with rigid bodies are not allowed in such cases if remeshing is required.

You cannot create or define Virtual Topology in the assembled system. As needed, define the required virtual topology features in the upstream systems. Furthermore, if you do define virtual topology, any change to the topology can cause scoping losses in the downstream system. You can correct scoping losses using the geometry Scoping Wizard.

The application does not currently support the ability to transfer parameters from upstream systems to the assembled system. As a result, upstream parameters will not be present in the assembled system.

Model systems do not support the following features. If present, updates to the project fail for the system transferring data to a downstream system. You need to suppress or delete these features before transferring data.

Any suppressed bodies from other upstream systems can be unsuppressed in the downstream environment provided they were meshed prior to being suppressed in the upstream system. However, suppressed parts from other upstream systems can never be unsuppressed in the downstream environment when using the External Model component system. These restrictions also apply when using the options Unsuppress All Bodies and/or Invert Suppressed Body Set.

Geometry from External Model is partially associative. When you have geometry from multiple External Model system assembled, and you refresh upstream model data into the downstream system, any geometry scoping that you have performed on an object in the downstream analysis will be lost for the modified External Model system only. That is, only External Model systems that you change lose scoping. For example, if you have two External Model systems assembled, System 1 and System 2, and you have objects scoped to geometry in the assembled system. If you modify System 1 and then refresh the upstream system, geometry scoping on objects is lost only for System 1. System 2 experiences no scoping losses. A more robust way to maintain scoping is to properly define imported Named Selections or criterion-based Named Selections.

Limitations similar to geometry associativity also apply to properties on bodies imported from External Model systems. Any changes made to properties on bodies imported from an External Model system in the assembled system are lost if the source External Model system is modified. Properties on bodies from other (unmodified) External Model(s) are maintained.

Cylindrical supports cannot be applied to mesh-based files imported using the External Model Component. You can instead apply equivalent loading using a Displacement load applied in appropriate cylindrical coordinate system.

During the assembly process, if named selections from different files (sources) have the same name, the application merges these named selections.