Technical Support

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In this article, the joint types supported by RecurDyn are described.

Please click the topics below for the detailed description.


A. General Joint

(1) Fixed Joint

A fixed joint constrains two bodies to locations defined by the user. The fixed joint icon looks like a bolt. A fixed joint secures the relative positions of two bodies and completely restricts their movement with no degree of freedom.



(2) Revolute Joint

A revolute joint fixes two bodies to one point, allowing rotational movement of the bodies about a rotational axis. The constraint equations include a three-dimensional positional equation, which states that two bodies are fixed to one point in a space, and a parallel equation, which states that the vectors of two bodies are parallel to each other. Therefore, a revolute joint constrains a total of five degrees of freedom regarding the positions and rotations of two bodies. This means there is only one degree of freedom between the two bodies. You can also constrain the motion of two bodies by expressing the degrees of freedom of the revolute joint regarding a rotational axis as a function of time.




(3) Translational Joint

A translational joint allows translational movement of two bodies in the direction of a vector defined between the bodies. A translational joint constrains rotational motion in all directions and only allows translational motion in the direction of a specified vector. This means it has only one degree of freedom and constrains the other five degrees of freedom. You can also constrain the motion of two bodies by expressing the translational degree of freedom as a function of time.




(4) Planner Joint

A planner joint only allows the sliding of a body on a plane and its rotational motion about an axis perpendicular to the plane.




(5) Cylindrical Joint

A cylindrical joint allows both translational and rotational motions of two bodies about a rotational axis that is defined between the bodies. You can also constrain the motion of two bodies by expressing the translational and rotational degrees of freedom as a function of time.




(6) Spherical Joint

A spherical joint fixes two bodies to one point and rotation is possible in all directions.




(7) Screw Joint

A screw joint allows a 360-degree rotation of a body per defined pitch about a rotational axis defined between two bodies.




(8) Universal Joint

A universal joint allows relative rotation of two bodies using the two rotational axes that are perpendicular to each other as shown in the figure.



(9) Constant Velocity

A constant velocity allows two bodies to maintain constant rotational velocity along the two rotational axes of two bodies.




B. Primitive Joint


There are a total of eight primitive joints as shown in the table below. Each primitive joint defines the constraint equation between two markers according to its properties. You can use different primitive joints at the same time to formulate the constraint equation that you want.


C. Special Joint


Special joints can bestow the following special constraints on bodies.



Degrees of freedom depending on the joint type


※ Degrees of freedom depending on the joint type




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