Create a Belt-Pulley Subsystem

In a belt-pulley system, a long flexible belt is used to transmit mechanical power by wrapping the belt around rotating pulleys. The power is transmitted due to friction between the belt and pulley surface. The belt-pulley subsystem in MotionView helps assemble such a system very quickly with a minimal inputs such as pulley center position, radius, and belt properties.

1. From the Assembly ribbon, click the Belt/Pulleys icon.
   The Add a Belt-Pulley Subsystem dialog is displayed.
2. Click the System collector and decide which system the belt/pulley needs to be created in.
3. Specify a variable name and label for the belt/pulley.
   By default, variable names of entities in MotionView follow a certain convention. For example, all belt/pulley entities have a variable name starting with bp_. This is the recommended convention to follow when building models in MotionView since it has many advantages in model editing and model manipulation.
4. Select the type of belt formulation to represent the belt using the drop-down menu.
5. If a reference frame other than global frame is to be used, select the reference marker for pulley coordinates by double-clicking on the Marker collector (located in the lower, left of the dialog).
   The belt-pulley system will be created such that the assembly lies within the XZ plane of the reference frame.
6. By default, two pulleys are available. To add or delete a pulley, use the right-click option on a row item indicating the pulley number.
7. Enter values for the X and Z coordinates of the pulley center in the reference marker coordinate frame.
8. Enter a value for the radius of the belt and specify which side (inner or outer) of the belt loop the pulley is positioned from the drop-down menu.
9. Specify the total number of pulleys to create.
   As the pulley is added/deleted, this field will be automatically updated.
10. Enter values for the belt width and belt thickness in the text boxes on the right side of the dialog.
11. A linear elastic Belt Rubber material is available in MotionView and is selected by default. To use a different material, double click on the MaterialProperty collector and select a different material from the list.
12. To create an NLFE belt formulation, complete the steps below:
    1. In the NLFE Belt Component area, the minimum number of NLFE beam elements required to accurately represent the belt based on the calculated belt profile is displayed in blue. By default, the minimum number of required elements is used. To use more elements, deactivate the Use minimum required option and specify the number of NLFE beam elements to be created.
    2. The effective diameter based on the calculated profile length of the belt in the installed position is also displayed in blue. By default, the dialog sets a value for the free diameter by a known amount of offset from the installed free diameter. Deactivate the Use calculated value option to provide a different value for the belt free diameter.
       Note: This number should be smaller than the installed belt diameter, so that the belt is sufficiently pre-tensioned. The greater the difference between the free diameter and the Installed diameter, the more pretension is induced.
13. To create a Discretized rigid bodies belt formulation, complete these steps:
    1. In the Belt Stiffness Properties section of the dialog, enter tensile stiffness and tensile damping values along the longitudinal direction of the belt.
    2. Enter bending stiffness and bending damping values along the bending direction of the belt.
    3. Enter a value for the pre-tension of the belt.
    4. For the Belt Contact Properties (Impact) section, the parameters are the same as that found in the Contact panel with Impact method. Refer to the Contacts tool topic to learn more about each of the parameters.
14. Once all the above information is entered, click OK to create the belt-pulley system and exit the dialog.
    The NLFE belt-pulley system that is created has the following architecture:

    Entity	Description
    Bodies	Rigid pulley bodies and an NLFE belt body consisting of a series of nonlinear beam finite elements are created.
    DataSet	A dataset where all editable values are stored. After the creation of the belt-pulley system, you can change the free diameter and width of the belt through this dataset.
    Points	The points that define the uninstalled belt profile and the pulley centers. These are hidden by default.
    Graphics	The graphics for the pulleys.
    Joints	Revolute joints between the pulley and attaching body. In addition, there are joints that connect the pulley and belt body that help in transmitting motion.
    Markers	A reference marker to define the uninstalled configuration of the belt (hidden by default).
    Template	Includes NLFE statements that are currently not supported by MotionView. These include GRIDS at the periphery of the pulley, LINE2 elements that model contact between belt GRID and pulley GRID, and CONN1 elements that restrain the belt with the pulley along normal of the belt-pulley plane.

    The discretized rigid bodies belt-pulley has the following architecture:

    Entity	Description
    Bodies	Rigid pulley bodies and a belt body consisting of a series of connected rigid bodies is created.
    DataSet	A dataset where all editable values are stored. After the creation of the belt-pulley system, you can change the free diameter and width of the belt through this dataset.
    Points	The points that define the uninstalled belt profile and the pulley centers. These are hidden by default.
    Graphics	The graphics for the pulleys and belt.
    Joints	Revolute joints between pulley and attaching body. In addition there are joints that connect the pulley and belt that hold the belt in the system plane.
    Markers	A reference marker to define the uninstalled configuration of the belt (hidden by default).
    Template	Includes MotionSolve command statements to hide the graphics used in contact.