Gears
About Gears
A gear is defined as a rigid body. A finite stiffness for the gear mesh (or gear tooth) can be specified in the gear pair node while connecting to other gears. Similar to the rigid domain, the gear is a material model, which is mutually exclusive to all other material models. The only material property needed is the mass density.
For details about the theory of a rigid body see Rigid Material in the Structural Mechanics Module User’s Guide.
The rest of this section has these topics:
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Gear Types
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Connection with Other Gears
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Center of Rotation
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Gear Axis
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Mounting Methods
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Connecting to Other Physics Interfaces
Gear Types
There are six type of gears available:
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Spur Gear
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Helical Gear
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Bevel Gear
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Worm Gear
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Spur Rack
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Helical Rack
The bevel and worm gears are available only in 3D.
Connection with Other Gears
A gear can be connected to other gears through following nodes:
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Gear Pair
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Worm and Wheel
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Rack and Pinion
A single gear can be connected to one or more gears.
Center of Rotation
Gears are defined through rigid-body degrees of freedom. These degrees of freedom are created at the center of rotation and the rotation is interpreted about this point. By default, it is set to the center of mass, but there are other ways to define it explicitly. This is the point where the forces and moment, that act on the gear due to meshing with other gears, are interpreted.
Gear Axis
The gear axis is the axis of rotation of the gear. It passes through the center of rotation. This axis is used to create the gear local coordinate system in the gear pair node. The gear rotation, a degree of freedom in the gear pair node, is also interpreted about this axis.
Mounting Methods
The motion of a gear can be constrained directly using its subnode. Alternatively, it can be mounted on a shaft. There are several ways through which a gear can be mounted on a shaft. Some of the commonly used methods are as follows:
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Directly mounted on a flexible shaft
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Mounted on a rigid or flexible shaft through a rigid or elastic fixed joint
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Mounted on a rigid or flexible shaft through a rigid or elastic hinge joint
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Mounted on a ground (a fixed shaft) through a rigid or elastic hinge joint
Connecting to Other Physics Interfaces
The multibody dynamics analysis of a geared system provides the contact force variation on the gear tooth and the vibration in various parts of the structure. These results can be further used for subsequent analysis.
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A stress analysis of a gear tooth or a full gear can be performed using the contact force obtained from the multibody dynamics analysis. This analysis can be performed within the Multibody Dynamics interface.
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A fatigue analysis of a gear tooth can be performed using the contact force variation over a mesh cycle or full revolution. This analysis can be performed using the Fatigue interface.
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A set of gears or a gear train operating at a high speed gives rise to high frequency vibration which results in noise. An acoustic analysis of a geared system can be performed using the normal acceleration of the vibrating surfaces. This can be performed using the Pressure Acoustics, Transient or Pressure Acoustics, Frequency Domain interfaces.