Joints table

Access:

On the Insert Joint dialog box, click the Display joints table icon.

Click the images in the upper section of the dialog box to move from one category of joints to another.

Standard joints

Standard joints are the most commonly used joints. These joints are based on different combinations of rotating and translating degrees of freedom. Available joints in this category are:

Revolution

Prismatic

Cylindrical

Spherical

Planar

Point-line

Line-Plane

Point-Plane

Spatial

Welding

Note: If Automatically Convert Constraints to Standard Joints is enabled, you can add spatial joints manually, however you cannot convert assembly constraints for one joint at a time.

Rolling joints

Although the images indicate that the joints can be used to simulate gear mechanisms, the actual meshing of the gear teeth is not accounted for. The method establishes a ratio based on geometry selected for the effective rolling radius of the gears.

Note: You must add a sketch to the part if geometry does not exist at the effective rolling radius.

Rolling: Cylinder on Plane

Rolling: Cylinder on Cylinder

Rolling: Cylinder in Cylinder

Rolling: Cylinder Curve

Belt

Rolling: Cone on Plane

Rolling: Cone on Cone

Rolling: Cone in Cone

Screw

Worm Gear

Sliding joints

Sliding: Cylinder on Plane

Sliding: Cylinder on Cylinder

Sliding: Cylinder in Cylinder

Sliding: Cylinder Curve

Sliding: Point Curve

Contact joint

The 2D contact joint is accurate. It detects when a collision occurs, but also allows separation to occur. Because the surfaces have no facets and are not penetrated, there is less chance of anomalies in the results. When working with mechanisms such as cams and followers, use these joints instead of 3D contact joints to accurately investigate the behavior of the mechanism. In some cases, you must create additional geometry on a part or use multiple 2D joints to achieve the appropriate results.

2D Contact

Geometry modification to ensure a continuous “smoothed” loop.

In order to provide a smoothed continuous loop for the 2D contact algorithm (to improve computation), a slight geometry modification is performed. All discontinuity in the profile is smoothed to have a continuous loop which enables the software to quickly solve the contact. The following example illustrates what takes place within the software.

	The example is a block, with planar faces, in contact with another component where not all faces are not parallel with the block faces. From a distance, the contact vectors (red) look as you would expect them to.
	If we zoom into the contact area for the non-parallel faces we see there is a slight overlap in the contact.
	Zooming into the contact area for the parallel face we see what is shown on the left.
	This condition occurs because Dynamic Simulation automatically creates fillets o smooth corners, as shown in the image on the left. As you can see, the contact is exact with respect to the fillet.
	In the case of the parallel faces joint, the contact is also exact with respect to the fillet.
	The software creates the fillet using the following method: Compute Lmin = shortest length between two segments. Draw the circle tangent to the two segments using a radius equal to 1/1000*Lmin. If the minimal value of 5e-6 mm is reached, then the vertex is not smoothed. In the example on the left, Lmin = 70 mm and the angle is perpendicular (90 deg), therefore the radius equals 0.07 mm.

Attention: The formula cannot be modified. If you want control over the fillet radius you must create the appropriate fillets in the model.

Force joints

3D Contact

Spring/Damper/Jack

Type	Parameters	Display	Comments
Spiral spring	Stiffness, Free length, Damping	Spiral spring	Default type. The force depends on the distance between the 2 points (stiffness and free length) and the velocity between them (damping).
Spring	Stiffness, Free length, Damping	separated, stacked cylinders	Same action as the Spiral spring. The display somewhat resembles a Belleville washer and optimizes display time.
Spring Damper	Stiffness, Free length, Damping	Spiral spring and damper	Same action as Spiral spring. The display is like an automobile shock absorber.
Damper	Damping	Damper	Only a damping action. The force depends on the velocity between the 2 points.
Jack	Input Grapher or Constant	Damper	Applies force parameter directly to the model. The graphic illustrates a jack type mechanism.