HyperMesh and BatchMesher

Mechanism Browser

Mechanism Browser

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Mechanism Browser

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The Mechanism browser is available in the LS-DYNA and RADIOSS user profiles.

Open the Mechanism browser from the menu bar by clicking Tools > Mechanism.

The Mechanism Browser is used to create and articulate a kinematic mechanism based on FE mesh.

You can undo and redo actions made in the Mechanism browser using the Undo and Redo commands on the Restore toolbar.

hmtoggle_plus1greyMechanism Browser Interface

The Mechanism browser consists of two panes. The first pane displays the mechanism structure which consists of joints, bodies, and constraints.The second pane displays the Entity Editor.

browser_mechanism

The following data is displayed in the Mechanism browser:

Column

Description

Entity

Lists the mechanism, joints, bodies, and constraints in your model.

ID

Displays the mechanism, joints, bodies, and constraints IDs.

Type

Displays the joint or constraints type.

Color

Displays the joint and body entity colors.

Body color is different from the component color set-up in the Model browser. The body color is activated when a body is in Review mode.

Lock level

Displays the lock level of a joint (green = free joint, yellow = locked joint).

 

hmtoggle_plus1greyEntity Editor

The Entity Editor is used to assign, modify, and quickly view the attributes defined inside Mechanism browser entities.

For example, once you create a new body or select a body in the browser, the Entity Editor opens and displays the bodies corresponding attributes, which you can view and modify.

From the Entity Editor, you can also create or edit an entity assigned to the selected body by right-clicking on the entity assignment field and selecting Create or Edit respectively.

entity_editor_mechanism

 

hmtoggle_plus1greyContext Menu

Option

Available for

Description

Actuate Mechanism

Mechanism

Gives the ability to articulate a mechanism by defining one of the following actions:

Translate a node
Rotate a body
Move a node to a target location

Check Mechanism

Mechanism

Enables you to check the validity of a mechanism, looking for common nodes, empty bodies, and redundant joints.

Collapse

All entities

Closes all of the folders for the selected mechanism, so that only the mechanism item displays.

Collapse All

In Mechanism browser

Closes all of the folders in the browser, so that only the mechanism items display.

Column Visibility

Mechanism and in Mechanism browser

Enables you to hide or show the ID, Type, Color, Lock, Common nodes, Empty Body and Redundant Joint columns in the browser.

Create

Mechanism and in Mechanism browser

Create a new mechanism, body, or constraint.

You can only create a body or constraint by right-clicking on a mechanism in the browser.

Delete

All entities

Deletes the selected entity.

Shortcut: To delete a selected entity in the Mechanism browser, press Delete.

De-Link Dummy

Mechanism

When a dummy has been linked to a mechanism, this option is activated in order to remove the link between the dummy and the mechanism.

Expand

All entities

Opens the selected folder, exposing every entity nested at every level.

Expand All

In Mechanism browser

Opens all of the folders in the browser, exposing every entity nested at every level.

Export Position

Mechanism

Opens the Export Position dialog, from which you can export a saved position of the selected mechanism into a solver file containing the corresponding solver transformation cards.

Hide

All entities

Turns off the entity in the graphics area. This selection affects each item’s local display control, that is, it will make the icon become ghosted indicating the display state is off.

Isolate

All entities

Displays only the selected entities, and turns off all other entities of the same type.

Link to Dummy

Mechanism

In case a dummy is present in the session, this option is activated in order to link the dummy, for example, to a seat mechanism.

Lock/Unlock Joint

Joint

Block (Lock) all degrees of freedom of the selected joint or make them free again (Unlock).

Move

Joint

Opens the Entity Editor to define the positioning values of the selected joint and activate the joint manipulator in the display that can be used to interactively move the joint.

Move Mechanism To

Mechanism

Moves the selected mechanism to its initial position or other positions, which have been previously saved.

Review

All entities

Invokes Review mode, which displays selected entities irrespective of their display state, masked, active state (Entity State browser), but not outside of the spherical clipping (if enabled).

By selecting a body, it will be displayed with its body color while other entities are grayed out and displayed with transparency.

By selecting a joint or a mechanism, the joint marker with the bodies links between will be displayed.

Reset Review

All entities

Resets the review of the previously selected entity.

Rename

All entities

Rename an entity in the Name field. The new name must be unique. All instances of the renamed entity will update automatically. You can cancel the rename operation by pressing ESC.

Save Position as

Mechanism

Save the displayed mechanism position as a new position or replace an already existing position.

Show

All entities

Displays the selected entity in the graphics area. The entities icon changes to bold indicating that the display state is on. Using the Show option on a mechanism or joint will display all nested entities inside.

XRef Entities

All entities

Opens the References browser and displays the relationship of the selected entities to other entities in the model in a hierarchical tree structure.

Any single entity or multiple entities can be selected.

 

hmtoggle_plus1greySupported Entities

A Mechanism (icon_mechanism) is the root of the hierarchy in the Mechanism browser. To create a Mechanism, right click in the Mechanism browser and select Create > Mechanism from the context menu. A mechanism is defined by the following entities:

Bodies (icon_bodies) define a kinematic assembly made of FE parts or nodes, which can be selected in the Entity Editor. To create a body, right click on the Mechanism and select Create > Body from the context menu.
Joints (icon_joints) define the kinematic relationship between two bodies (for the following joint types: Ball, Cylinder, Revolute, Slider) or three bodies (for the DoubleSlider joint). To create a joint, select two bodies to connect in the browser, then right click and select Connect from the context menu. For the DoubleSlider joint, the third body has to be defined in the Entity Editor.
Constraints (icon_constraints) define kinematical constraints on a body at a specified node or point location.

 

hmtoggle_plus1greySupported Keywords Exported in Solver Deck

The mechanism information is embedded in the input deck using keywords following the /END (for RADIOSS) or *END (for LS-DYNA).

For RADIOSS, a mechanism is defined between the /MECHANISM_START and /MECHANISM_END keywords, and is composed of:

/ASSEMBLY defines a body with the following attributes:
oAssembly ID
oAssembly name
oNumber of part sets and related set IDs
oNumber of parts and related part IDs
oNumber of node sets and related set IDs
oLocked degrees of freedom
oOptional local coordinate system
/CONNECTION_ defines a joint between assemblies with the following attributes:
oConnection name
oAssembly ID #1
oAssembly ID #2
oConnection position (defined by Node IDs or connection position coordinates)
oJoint limits in + and - directions
oCurrent joint distance/angle value
oLock level
oAssembly ID #3 (for the Double Slider only)
oScale factors for relative displacement between Assembly #3 and Assembly #1 and #2
/POSITION defines, for a stored position, the position information for the mechanism’s assemblies with the following attributes:
oPosition name
oAssemblies position matrixes

Note: The Reference and Initial positions should never be deleted inside the mechanism.

/CHILD_DUMMY defines the coupling between a mechanism and a dummy with the following attributes:
oName
oMaster assembly ID of the mechanism
oDummy ID
oNumber of child assemblies of the dummy
oDegrees of freedom linking master to child
oChild assembly IDs of the dummy

 

The following connection keywords can be defined, depending on the type of joint created in the Mechanism browser:

/CONNECTION_PIN defines a ball joint
/CONNECTION_HINGE defines a revolute joint
/CONNECTION_LINE defines a cylindrical joint, or a double slider joint if assembly ID #3 is defined or a slider joint has the #HM_SLIDER_JOINT comment defined before the name of the connection

 

For LS-DYNA, the same keywords are used but their syntax begins with  * and not /.

 

 

 

 

 

 

See Also:

Basic Browser Operations

Positioning Mechanisms

Linking a Dummy to a Mechanism