Engineering Solutions

FE Absorb utility

FE Absorb utility

 Previous topic Next topic Expand/collapse all hidden text  

FE Absorb utility

 Previous topic Next topic JavaScript is required for expanding text JavaScript is required for the print function  

Use the FE Absorb utility to add (absorb) certain FE information into connectors. FE weld entities or specific FE group definitions can be considered.  This functionality is useful in creating connectors for legacy FE solver models, allowing you to convert between various realization types or use any other connector functionality.

The utility includes separate functions for absorbing welds, bonds and masses:

•For welds, all FE entities that belong to the selected weld type (such as bar2, ACM, and so on) will be identified as spots.
•For bonds, all FE entities that belong to the selected bond type (such as adhesive) will be identified as adhesives. The adhesive is represented by solids (hexas, pentas) with attached 1D elements.
•Currently mass absorption works only for non structural masses organized via group definitions. One connector is absorbed per NSM group.

Once the appropriate FE is identified, the absorb function creates a new connector for each cluster and associates the existing FE entities as realization of the connector. The newly created connector also holds any relevant information about links.

The utility includes separate tabs for spots, adhesives and applied masses:

 

FE Absorb Utility Tabs and Input

Functionality is broken into different tabs for different types of connectors:

hmtoggle_arrow1Spot Tab

fe_absorb_menu

Input

Description

FE configs

Type of FE realization (one or more entities) that needs to be converted to connectors.  For example, rigid identifies all rigid elements in the model and creates connectors for each one of them.  The FE config can be a simple type (weld, rigids, spring, and so on) or custom types defined in the FE config file (ACM, LS-DYNA MAT100, and so on). For custom types, the FE type can be chosen in an additional line.

Elem filter

Allows you to choose between selecting the displayed elements or a smaller selection from which you can identify and create connectors.  The available options are:

•All

Checks all elements to find any FE corresponding to the chosen FE config, and converts them to connectors.
•Select

Activates an element collector allowing you to select a portion of the model.  In this case, the function searches only the selected elements to find the FE corresponding to the chosen FE config and converts them to connectors.

Elements

Only available when Elem filter is set to select.  Allows you to select the elements from which the FE corresponding to the chosen FE config, are determined and converted to connectors.

To clear the elements selector, and de-select all elements, click reset

FE connectivity

Provides information on how the selected FE config is connected to the connecting parts (links).  For many FE config types, this option is predetermined.  But for some types of weld representations, multiple configurations of connectivity are valid.  In such cases, you should select the type that is best for the model.  For example, a Nastran CWELD element is a mesh-independent weld, which does not directly connect to the shell elements; depending on how it was generated, plot elements are sometimes used to connect the CWELD to the shells.  In such situations, you should select option 2 - mesh independent (head), rather than option 3.  Depending on the FE config selected, one or more connectivity types are valid.  The three types available are:

i-mesh_dependent

Mesh dependent

Valid for weld elements that share nodal connectivity with the connecting shell parts.

i-mesh_independent

Mesh independent (head)

Valid for weld elements that are mesh-independent (do not share nodal connectivity with the connecting shell parts) but are connected to the shell parts via secondary entities (plot elements, equations, and so on.)

i-mesh_independent2

Mesh independent (projs)

Valid for weld elements that are mesh independent (do not share nodal connectivity with the connecting shell parts) and are not connected to the shell parts in any way.  Only their projections fall on the shell elements.

Enable acm pattern recognition

When active, particular emphasis is placed on identifying the diameter and the hexa pattern, and connector attributes are appropriately updated.

During the absorption, ACM hexa elements and the attached RBE3 elements are identified. A new connector is created at the center of the hexa elements, and the hexa as well as the RBE3 elements are registered on the green (realized) marked connector.

Only available for various custom ACM realization types.

If hexa thickness type is ambigous

During absorption of ACM (general), three versions are differentiated (shell gap, equivalence (T1+T2)/2), and constant thickness) and the thickness is determined. Appropriate attributes assigned to the connector, which allows the same rerealization.

Where there is not a clear identifier between shell gap and equivalence(T1+T2)/2, the following options will determine the preference:

•Prefer shell gap - Shell gap attributes are preferred when the thickness type is ambiguous.
•Prefer equival(T1+T2)/2 - Equivalence (T1+T2)/2 attributes are preferred when the thickness type is ambiguous.

 

Only available for the absorption of the custom ACM (general) realization type.

Maximum link distance

Only connections in which the link distance is smaller than this value are considered for absorption.  Depending on the unit system used, it may be useful to increase or decrease the value.  Very large values can affect performance.

Re-connect rule:

Useful in situations where the parts to be connected have been changed/replaced.  While realizing the connector, Engineering Solutions looks for link entities based on the re-connect rule:

•Use id

Use the selected link entity’s IDs to re-connect.  If the link entity is not currently in the model, the connector with this re-connect rule will search for entities with the same ID.
•Use name

Use the selected link entity’s names to re-connect.  If the link entity is not currently in the model, connectors using this re-connect rule search for entities with the same name.

Move connectors to FE component

When active, this option saves the connector entities into the component of the mesh that they are linked to.

Save MCF

This optional feature allows you to export all the connectors that have been created from FE to a master connection file.  Type in a new file name, or click Open and select the file name for the master connection file.  If this field is left blank, the master connection file is not created.

Absorb

Performs the FE absorb process.  In this process, all the entities that comprise an FE config are identified.  A connector is created at each such location and all the FE entities are added to the realization of the connector.

This process does not (re-)create or renumber any new FE entities; it simply takes the identified group of existing FE that forms a connector and marks it as the realization of the connector.  For example, if you choose to absorb all the ACMs in a model, it identifies the hexa elements and the attached RBE3 elements; creates a new connector at the center of the hexa elements; then adds the hexa elements and all the RBE3 elements as the FE realization of the connector (marking the connector as realized/green).

Note:The absorbed FE may not be the same as the ones realized by Engineering Solutions; the absorbed FE behaves similar to the FE created within Engineering Solutions as part of the connector realization. If you choose to unrealize that connector, or realize it with a new FE type, these absorbed FE are deleted.

 
hmtoggle_arrow1Solid Seams and Areas tab

fe_absorb_menu_adhesives

The following options are available in the Adhesive tab of the FE absorb utility:

Input

Description

Elem filter

Allows you to choose between selecting the displayed elements or a smaller selection from which you can identify and create connectors.  The available options are:

Displayed

Search the displayed elements to find the FE entities representing adhesives, and convert them to connectors.

Select

Activates an element collector, allowing you to select a portion of the model.  In this case, the function searches only the selected elements to find the adhesive representations and convert them to connectors.

Elements

Only available when Elem filter is set to select.  Allows you to select the elements from which the FE corresponding to bonds are determined and converted to connectors.

Note:It is recommended to only select real adhesive elements, in order to minimize the absorption time.

To clear the elements selector, and de-select all elements click reset.

enhanced approach

The absorption of solid seams and area connectors can be performed on all elements in a model.

In order to identify valid connector elements from such a selection, instead of identifying regular solid parts as connections, certain characteristics need to be true.

Note: The pre-selection of valid connection elements helps to absorb connectors faster.

Select this checkbox when some of the characteristics the tool is looking for might be too strict for certain connections, thus preventing them from being absorbed, even though they represent solid connections.

The enhanced approach requires a pre-selection of only connection elements. The complete selection is treated as valid connection elements, and only connector creation and link detection is performed.

Seam

When activated, hexa adhesives and Penta (Mig) can be absorbed as seam connectors as long as they have a regular pattern. Regular means that the section does not change along the seam.

If the hexa adhesive does not have a regular pattern, it might be absorbed as area connectors, if the check for area is marked. This will also happen for adhesives with regular patterns, if the seam checkbox is not marked.

During absorption the element pattern, dimensions, and tolerance will be detected and stored on the connector.

•With head only - Only consider solid connections with head elements for absorption.

It is recommended that you use this option in case you have connections with heads, because it will lead to a better performance and a safer link detection.

Check this box off to also consider connections without head elements. Link detection will rely on projections.

Area

When activated, hexa adhesive with irregular patterns can be absorbed as area connectors as long as they have a clear number of coats.

During absorption the number of coats and tolerance will be detected and stored on the connector.

•With head only - Only consider solid connections with head elements for absorption.

It is recommend that you use this option in case you have connections with heads, because it will lead to a better performance and a safer link detection.

Check this box off to consider connections without head elements. Link detection will rely on projections.

•Area connector mid-position - Position and absorb area connectors into the middle of the hexa adhesive realization. By default, this option is activated.
•Consider single element cluster -  Identify element clusters using certain rules during absorption. This approach finds plane solid (hexas, pentas) element constellations which are connected to 1D elements on two opposite sides.

This option provides better control of the identification of adhesives. The general identification approach allows the creation of adhesive connectors even from single elements, if all other rules are observed. Normally these single elements should be absorbed into spots; this checkbox allows you to also absorb single elements into an adhesive connector.

However, to prevent you from doing this by mistake, even when this option is selected, it only becomes activated if all of the selected 3D elements belong to a unique component.

 

Area connector mid-position

When activated, area connectors will be positioned and absorbed into the middle of the hexa adhesive realization. This option is activated by default.

Group links

During absorption the top and bottom side of the solid connection is identified.

When Group links is enabled, all found links connected to the top side of the solid connection are combined into one group link and all of the found links connected to the bottom side are combined to a second group link.

When realizing a connector that is defined with group links it is guaranteed that at each testpoint valid projections for both group links have to be found in order to have a successful connection. That behavior encourages more reproducible results.

Maximum link distance =

Only connections in which the link distance is smaller than this value are considered for absorption.  Depending on the unit system used, it may be useful to increase or decrease the value.  Very large values can affect performance.

Re-connect rule:

Useful in situations where the parts to be connected have been changed/replaced.  While realizing the connector, Engineering Solutions looks for link entities based on the re-connect rule:

•Use id

Use the selected link entity’s IDs to re-connect.  If the link entity is not currently in the model, the connector with this re-connect rule will search for entities with the same ID.
•Use name

Use the selected link entity’s names to re-connect.  If the link entity is not currently in the model, connectors using this re-connect rule search for entities with the same name.

Move connectors to FE component

When active, this option saves the connector entities into the component of the mesh that they are linked to.

Save MCF

This optional feature allows you to export all the connectors that have been created from FE to a master connection file.  Type in a new file name, or click Open and select the file name for the master connection file.  If this field is left blank, the master connection file is not created.

Absorb

Performs the FE absorb process. In this process, all the entities that comprise an FE config are identified. A connector is created at its location and all the FE entities are added to the realization of the connector.

This process does not (re-)create or renumber any new FE entities; it simply takes the identified group of existing FE that forms a connector and marks it as the realization of the connector.

Note:The absorbed FE may not be the same as the ones realized by Engineering Solutions; the absorbed FE behaves similar to the FE created within Engineering Solutions as part of the connector realization.  If you choose to unrealize that connector, or realize it with a new FE type, these absorbed FE are deleted.

 
hmtoggle_arrow1Apply Mass tab

fe_absorb_menu_apply_mass_tab

The following options are available in the Apply Mass tab of the FE absorb utility:

Input

Description

Group filter

Allows you to choose between using all groups or doing a smaller selection of certain groups.  The available options are:

•All

Searches through all groups to find the groups defining non structural masses. These groups get references to the appropriate connectors during absorption. The properties or elements referenced in the groups will become component or element links on the connector.
•Select

Activates a group collector, allowing you to select certain groups in the model.  In this case, the function searches only through the selected groups to find the groups defining non structural masses. These groups get references to the appropriate connectors during absorption. The properties or elements referenced in the groups will become component or element links on the connector.

Groups

Only available when Group filter is set to select.  Allows you to select the groups.

To clear the groups selector, and de-select all groups, click reset.

NSM Entity Type

The connector created during NSM absorption gets an NSM entity type attribute. It is written into the connector and is considered during the next realization. It also influences the state of the absorbed connector (see below).

Upon creation of nsm connectors, the FE data (nsm group entity) is realized and a new component (CE_Mass_inc_<include name>) is created inside the current include.  The newly created connectors will reside in this new component.  Each include is meant to host its own CE_Mass_inc_<include name> component, and HM will produce a warning if the component name already exists in a different include.  This helps ensure that unrealizing and rerealizing nsm connectors will keep the FE data in its original include.

The absorption routine always looks for elements which exclusively reference to the same property (directly or indirectly) and can be combined into one or more component links. If this is not possible, the single elements are linked in the connector individually. Thus, the links created during the absorption look the same independent of the settings for the NSM entity type attribute.

Three different attributes can be set to the absorbed connectors:

•elements

The absorption creates a realized (green) connector for each NSM group. A later re-realization creates element based NSMs.

Note:Even if the NSM group was defined based on properties before, the new realized NSM group will be element-based.
•property

The absorption creates a connector for each NSM group. Most models, especially in the automotive industry, are organized in such a way that there is a one-to-one relationship between a property and a component. If this is the case the absorption with exclusively component-based links, and the re-realization into property based NSM groups, will not be a problem. See if not possible below.
•if not possible

Sometimes it is not possible to identify exclusive properties for a clear re-realization as property-based NSM groups. For those cases the following sub-attribute decides how to proceed with the absorbed connectors.
-type Elements: If this sub-attribute is set the absorption creates a realized (green) connector for NSM groups which cannot clearly be defined with properties.
A later re-realization creates element-based NSM groups.
-fail connector: If this sub-attribute is set the absorption creates a failed (red) connector for NSM groups which cannot clearly be defined with properties.
Note:After a sufficient reorganization of the properties a successful re-realization as property-based NSM groups might be possible.

re-connect rule

This option is useful in situations where the entities to be connected will be exchanged in a subsequent process. While re-realizing the connector, Engineering Solutions looks for link entities based on the re-connect rule:

•none

No re-connect rule is defined.  If the link entity is not currently in the model, the connector with this re-connect rule will fail to realize.

If no re-connect rule is defined for a link, this link disappears from the connector when the linked entity is deleted.
•use id

Use the selected link entity’s IDs to re-connect.  If the link entity is not currently in the model, the connector with this re-connect rule will search for entities with the same ID.
•use name

Use the selected link entity’s names to re-connect.  If the link entity is not currently in the model, connectors using this re-connect rule search for entities with the same name.

Save MCF

This optional feature allows you to export all the connectors that have been created from FE to a master connection file.  Type in a new file name, or click Open and select the file name for the master connection file.  If this field is left blank, the master connection file is not created.

Absorb

Performs the FE absorb process.  In this process all selected non structural mass groups are identified  and a mass connector is created for each of these groups.  The group is then referenced to the appropriate connector. The connector position is in the middle of a virtual box surrounding all referenced group elements.

This process does not (re-)create or renumber any new FE entities; it simply marks groups as realizations of connectors.

Note:The absorbed non structural mass may not be the same as the ones realized by Engineering Solutions.  This strongly depends on the defined NSM entity type attribute. See the section Expected behavior for NSM absorption dependent on the initial situation and the absorptions options set, below, for a detailed description of the different scenarios.

If you choose to unrealize that connector, the referenced group is deleted.

 

 

Expected Behavior for NSM Absorption Dependent on the Initial Situation and the Absorptions Options Set

hmtoggle_arrow1The default option during absorption is “NSM on Property and if not possible on Elements”

This includes Four scenarios:

1.NSM defined on Property - the elements referencing the listed properties can be described by complete components. This is always the case if the properties are exclusively assigned indirectly via the components. In rare cases this also works for direct property assignment.
•connector can be created exclusively with components as links
•connector is marked as on property or on elements
•connector is green
•successful re-realization as NSM defined on Property
2.NSM defined on Property - the elements referencing the listed properties cannot be described by complete components because of direct property assignment on some elements.
•connector can only be created as a mixture of component and element links
•connector is marked as on property or on elements
•connector is green
•successful re-realization as NSM defined on Property
3.NSM defined on Elements - listed elements can be described by complete components.
•connector can be created exclusively with components as links
•connector is marked as on property or on elements
•connector is green
•successful re-realization as NSM defined on Property or on Elements. (On Property only if the properties referenced by the linked components are not referenced from somewhere else, for example, not linked components.)
4.NSM defined on Elements - listed elements cannot be described by complete components.
•connector can only be created as a mixture of component and element links
•connector is marked as on property or on elements
•connector is green
•successful re-realization as NSM defined on Property or on Elements. (On Property only if the properties referenced by the linked elements are not referenced from somewhere else, for example, not linked components.)

 
hmtoggle_arrow1Option during absorption “NSM on Property and if not possible fail connector”

Four scenarios:

1.NSM defined on Property - the elements referencing the listed properties can be described by complete components. This is always the case if the properties are exclusively assigned indirectly via the components. In rare cases this also works for direct property assignment.
•connector can be created with exclusively components as links
•connector is marked as “on property or fail connector”
•connector is green
•successful re-realization as NSM defined on Property
2.NSM defined on Property - the elements referencing to the listed properties cannot be described by complete components because of direct property assignment on some elements.
•connector can only be created as a mixture of component and element links
•connector is marked as “on property or fail connector”
•connector is green
•successful re-realization as NSM defined on Property
3.NSM defined on Elements - listed elements can be described by complete components.
•connector can be created exclusively with components as links
•connector is marked as “on property or fail connector”
•connector is green or red (green only if the properties referenced by the linked components are not referenced from somewhere else, for example, not linked components.)
•re-realization as NSM defined on Property. Successful only if the properties referenced by the linked components are not referenced from somewhere else, for example, not linked components.
4.NSM defined on Elements - listed elements cannot be described by complete components.
•connector can only be created as a mixture of component and element links
•connector is marked as “on property or fail connector”
•connector is green or red (green only if the properties referenced by the linked elements are not referenced from somewhere else, for example, not linked components.)
•re-realization as NSM defined on Property. Successful only if the properties referenced by the linked elements are not referenced from somewhere else, for example, not linked components.

 
hmtoggle_arrow1Option during absorption “NSM on Elements”

Four scenarios:

1.NSM defined on Property - the elements referencing the listed properties can be described by complete components. This is always the case if the properties are exclusively assigned indirectly via the components. In rare cases this works for direct property assignment as well.
•connector can be created exclusively with components as links
•connector is marked as “on Elements”
•connector is green
•successful re-realization as NSM defined on Elements
2.NSM defined on Property - the elements referencing the listed properties cannot be described by complete components because of direct property assignment on some elements.
•connector can only be created as a mixture of component and element links
•connector is marked as “on Elements”
•connector is green
•successful re-realization as NSM defined on Elements
3.NSM defined on Elements - listed elements can be described by complete components.
•connector can be created exclusively with components as links
•connector is marked as “on Elements”
•connector is green
•successful re-realization as NSM defined on Elements
4.NSM defined on Elements - listed elements cannot be described by complete components.
•connector can only be created as a mixture of component and element links
•connector is marked as “on Elements”
•connector is green
•successful re-realization as NSM defined on Elements

 

 

See Also:

Connectors Module

Alphabetical List of Panels