Chain Drive
Use the Chain Drive () node to model a roller chain sprocket assembly in 2D or 3D. This node determines the interaction of the roller chain sprocket assembly, and automatically generates a set of physics nodes that are necessary to describe its behavior.
The geometry of the roller chain sprocket assembly can be created from the COMSOL Part Library. These parts include a set of domain and boundary selections used for the automatic generation of physics nodes. It is also possible to create or import your own geometry. However, in this case, you need to manually create the domain and boundary selections required by the Chain Drive node.
See the Chain Drive and Chain Geometries sections for more details about chain modeling, geometry creation, and selection settings.
Create Links and Joints
Click the Create Links and Joints button () to automatically generate the physics nodes required to model the chain drive. Clicking this button makes the following changes in the Multibody Dynamics interface:
Creates a number of Rigid Domain nodes collected under a node group named cdr1: Link (Rigid Domains). This node group is only generated if Link type is set to Rigid or Rigid with elastic bushing.
cdr1 is the default name for the first instance of the Chain Drive node and can be changed if needed.
Creates a number of Attachment nodes collected under a node group named cdr1: Link (Attachments).
Creates a number of Hinge Joint nodes collected under a node group named cdr1: Link (Hinge Joints). A Joint Elasticity subnode is added to all the joints if Joint type is set to Elastic.
Creates a node group named cdr1: Sprocket containing two Rigid Domain nodes, two Attachment nodes and two Hinge Joint nodes. These attachment and joint nodes are only generated if the Include sprocket mounting joints check box is selected. The rigid domains are only created if Sprocket type is set to Rigid.
Creates a node group named cdr1: Bushing containing a Linear Elastic Material node. Its selection input includes all bushing domains. This node group is only generated if Link type is set to Rigid with elastic bushing.
Creates a node group named cdr1: Contact containing a Contact node to model the contact between the sprockets and the chain links. This node group is only generated if Contact method is set to Mesh based.
Creates a Contact Pair named Contact: Sprocket-Roller under Definitions. The source and destination selections of this Contact Pair are set automatically. This node is only generated if Contact method is set to Mesh based.
Only click the Create Links and Joints button after setting appropriate values for all parameters in the Chain Drive node. The parameters are described in the following sections.
If you change one or more parameters of the Chain Drive node after the automatic creation of physics nodes, the settings of the associated physics nodes also requires an update. Click the Create Links and Joints button again in order to update the settings of the existing physics nodes. A warning message is added under the Chain Drive node to notify when such an update is required.
If any selection or related parameters of the Chain Drive node are modified after the automatic creation of physics nodes, all associated physics nodes needs to be recreated. Click the Create Links and Joints button again in order to do this. Since all physics nodes are deleted and created again during this operations, the update may take a while. A warning message is added under the Chain Drive node to notify when such an update is required.
Domain Selection, Link
Select the domains of all chain links of the roller chain sprocket assembly here. If you use a geometry from the COMSOL Part Library, a built-in domain selection named Links is automatically selected. This selection is used to create a Rigid Domain node for each link plate. This selection input is only available when Link type is set to Rigid or Rigid with elastic bushing.
Domain Selection, Sprocket
Select the domains of both sprockets of the roller chain sprocket assembly here. If you use a geometry from the COMSOL Part Library, a built-in domain selection named Sprockets is automatically selected. This selection is used to create a Rigid Domain node for each of the two sprockets. This selection input is only available when Sprocket type is set to Rigid.
Domain Selection, Bushing
Select the domains of the bushings of the roller chain sprocket assembly here. Bushings are the components present between the roller plate and the pin plate of a chain link. If you use a geometry from the COMSOL Part Library, a built-in domain selection named Bushings is automatically selected. This selection is used to create a Linear Elastic Material node for the bushing domains. This selection input is only available when Link type is set to Rigid with elastic bushing.
Boundary Selection, Pin
For 3D models, select the outer cylindrical surfaces of the pin plates here. If you use a geometry from the COMSOL Part Library, a built-in boundary selection named Pin Outer Boundaries is automatically selected.
For 2D models, select the inner boundaries of the pin plates here. If you use a geometry from the COMSOL Part Library, a built-in boundary selection named Pin Inner Boundaries is automatically selected.
This selection is used to create an Attachment node on the outer boundary of each pin plate. This selection input is always available.
Boundary Selection, Roller Inner
For 3D models, select the inner cylindrical surfaces of the roller plates here. For 2D models, select the inner boundaries of the roller plates. If you use a geometry from the COMSOL Part Library, a built-in boundary selection named Roller Inner Boundaries is automatically selected. This selection is at the same geometrical position as that of the Pin Outer Boundaries selection.
This selection is used to create an Attachment node on the inner boundaries of each roller plate. This selection input is always available.
A Hinge Joint is created for each roller plate and pin plate pair, where the Attachment nodes belonging to the pair are set as source and destination of the hinge.
Boundary Selection, Roller Outer
For 3D models, select the outer cylindrical surfaces of the roller plates here. For 2D models, select the outer boundaries of roller plates. This selection is used to model the contact between the chain links and the sprockets. If you use a geometry from the COMSOL Part Library, a built-in boundary selection called Roller Outer Boundaries is automatically selected.
Boundary Selection, Sprocket Outer
Select the outer curved boundaries of the sprockets here. This selection is used to model the contact between the chain links and the sprockets. If you use a geometry from the COMSOL Part Library, a built-in boundary selection called Sprocket Outer Boundaries is automatically selected.
When Contact method is set to Mesh based, this selection and the roller outer boundary selection are used to create a Contact Pair node between the chain links and the sprockets. If Contact method is set to Roller center based, these selections are used for a penalty based rigid contact formulation.
Boundary selection, Sprocket Inner
Select the inner boundaries of sprockets here. This selection is used to mount each sprocket on a shaft. If you use a geometry from the COMSOL Part Library, a built-in boundary selection called Sprocket Inner Boundaries is automatically selected.
This selection is used to create an Attachment and a Hinge Joint node on the inner boundary of each sprocket. It is only available when the Include sprocket mounting joints check box is selected.
Selection Settings
For the automatic creation of physics nodes, the Chain Drive node requires a set of domain and boundary selections. In the Chain selections drop-down menu, chose whether the selections are to defined by From part instance or User defined.
When Chain selections is set to From part instance, the Part instance drop-down menu lists all roller chain sprocket assemblies present in the Geometry node. You can choose any one of them. The selections in the chosen part are automatically identified and taken as the input to the selections required by the Chain Drive node. Since the selection inputs are automatically set, they are in a non-editable state. However, you can edit them by selecting the Manual control of selections check box.
When Chain selections is set to User defined, you have to manually create a set of appropriate domain and boundary selections, and associate each selection with the correct selection input in the Chain Drive node.
Chain Settings
Specify the name of chain drive in the Name field. By default, the name is cdr1 for the first instance created; it can, however, be any string. To easily identify the physics nodes created from a specific Chain Drive node, the Name string is used as an identifier for all node groups and physics nodes it creates.
Chain links can be rigid or elastic. You can also model the effect of elastic bushings between the rigid link plates. Determine the behavior by selecting a Link type Rigid, Rigid with elastic bushing or Elastic.
If Link type is set to Rigid, a Rigid Domain node is automatically created for each link plate. If Link type is set to Rigid with elastic bushing, a Linear Elastic Material node is additionally created for the bushing domains between every roller and pin plate.
Select a Sprocket type Rigid or Elastic. If Sprocket type is set to Rigid, a Rigid Domain node is automatically created for each sprocket.
If Link type or Sprocket type is set to Elastic, the Chain Drive node does not create any specific material model node. For these cases, the default Linear Elastic Material node is used for modeling the elastic bodies.
Select a Contact method Roller center based or Mesh based. The contact method is used to model the contact condition between the chain links and the sprockets. The Roller center based contact method is available when Link type is Rigid or Rigid with elastic bushing. If the Roller center based contact method is selected, specify a Penalty factor (pc) used in the contact condition.
When either the links or the sprockets, or both, are elastic bodies, the Mesh based contact method is available. When the Contact method is set to Mesh based, a Contact Pair node is created under Definitions, and a Contact node with the Penalty formulation is created in the physics.
Joint Settings
For 3D models, select a Sprocket AxisFrom selected part, Specify direction, or Select a parallel edge. Relative rotation between chain links is only allowed about the sprocket axis.
From selected part is available only when Chain selection is set to From part instance. This automatically takes the value of the sprocket axis from the geometry part selected in the Part instance input.
For Specify direction, enter a value or expression for e0. The default is (0, 0, 1).
For Select a parallel edge, select an edge in the automatically added Sprocket Axis subnode. Any edge in the model can be used to specify the sprocket axis. Select the Reverse direction check box to reverse the direction of the sprocket axis.
For all above methods, the sprocket axis is also used to define the direction vector e0 of each Hinge Joint node created by the Chain Drive node.
Select an Attachment type Rigid or Flexible. The selected Attachment type determines the Connection type in all Attachment nodes created by the Chain Drive node.
Select a Joint type Rigid or Elastic. Select an option from the list to determine whether the Hinge Joint nodes created by the Chain Drive node should be fully rigid or elastic. When Rigid is selected, the Joint Elasticity input in every Hinge Joint node is automatically set to Rigid joint. When Elastic is selected, a Joint Elasticity subnode is added to the Chain Drive node. The elastic properties given in this node are used in the Joint Elasticity subnode created automatically under every Hinge Joint node.
Select the Include rotational damping check box to add a Spring and Damper subnode with a rotational Damping coefficient c to every Hinge Joint node.
Select the Include sprocket mounting joints check box to automatically create an Attachment and a Hinge Joint node with a Fixed source for each sprocket.
Advanced
Select the Allow attachments and rigid domains in other joints check box to announce the Rigid Domain and Attachment nodes related to the chain link in the list of Source and Destination in other Joint nodes. The attachments related to the sprockets are always announced to other joints.
Location in User Interface
Context Menus
Ribbon
Physics tab with Multibody Dynamics selected: