Autodesk Inventor's New Joint Connections

30 Mar, 2015 By: Elvis R. Sverko

IMAGINiT Tricks Tutorial: Inventor's Joint Connections are easier to use and have more flexibility compared to Constraints.

Part of the answer is in how Joint Connection chooses the origin points to connect geometry. With Constraint you must select a face, edge, or point individually, and with Joint Connection you choose a point and face, or a point and edge together. The points may be an end point or corner point, or a middle point or center point.

In this example, it's easy to select both a point, a face, or an edge, all at once with the Rigid joint connector type, which lets you remove all six degrees of freedom of a component using just one relationship feature instead of three (Mate, Flush, Flush). This component is now a stationary component in the assembly and doesn't move. This method saves you time because you don't have to place additional features (such as Constraints) and yet you end up with the same results. This method is much simpler.

Not only is this method simpler for a stationary component, it is also simpler for components that contain motion. However, the process is completely different.

With Constraints, you are always concerned about removing degrees of freedom in the direction the component is not to move, but with Joint Connections, you only worry about the degrees of freedom in the direction the component is to move. When you select this degree of freedom, all other degrees of freedom are automatically removed.

An Example. To highlight this point, let's consider a component that rotates, such as a hinge. Instead of removing the three translational degrees of freedom and two rotational degrees of freedom how the component is not supposed to move (by using multiple Constraints, Mate, and Flush), with Joint Connection you note that the component must rotate along an edge and only needs one joint connection (rotational) applied, and the action of motion is complete. In either case, only a single rotational degree of freedom remains.

Joint Connections also add Limits (defines the allowable range of motion of the remaining degrees of freedom), Lock (maintains the current position of a component until a connected component position is changed), and Protect (alerts if an added relationship violates a required degree of freedom).

Whether these are performed via Constraints or Joint Connections, they are all Relationships of an assembly and they all are listed in the Assembly Browser under each component, as well as under the main Relationship node. They can be used together on individual components to fully construct the assembly or you can just use Joint Connections.

One final positive to using Joint Connections is that when you bring an assembly into Autodesk Inventor 2014's Dynamic Simulation Environment, they are automatically converted one-to-one into Joints for simulation purposes. You can easily identify which joints are created because of this one-to-one conversion. With Constraints, you have to understand which constraints are used, which degrees of freedom are still available, and try to decipher which Joints the Dynamic Simulation would convert them into.

Now do you can see why Joint Connections are the new Constraints? Save yourself time and headaches and use Joint Connections.

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About the Author: Elvis R. Sverko

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