This section examines the steps to manually create joints. Refer to the Automatic Joint Creation section of the Help for a discussion about how to create joints automatically.
To add a joint manually:
The Joints object is a child object of the Connections object. The Connections object is typically generated automatically. As needed, highlight the Model object in the tree and choose the option from the Model Context Tab once you have imported your model.
Highlight the Connections object and open either Body-Ground menu or the Body-Body menu from the Connections Context Tab and then select your desired Joint Type. The new joint object becomes the active object in the tree.
Once inserted and active, there are a number of joint properties that require definition. For a detailed description of each of these properties, refer to the Joint Properties Help section.
Note: You can pre-select a vertex or node (Body-Ground) or two vertices or nodes () and then insert a Joint to automatically create a directly attached joint.
Tip: The option on the Context tab displays the Reference and Mobile bodies in separate windows with appropriate transparencies applied. You have full body manipulation capabilities in each of these windows.
Once you have defined the desired joint properties, you may wish to use the tool. The tool is activated by selecting the option on the Context Tab. This feature positions the Mobile body according to the joint definitions. You can then manipulate the joint interactively (for example, rotate the joint) directly on the model. The notes section shown below provides additional information about the benefits and use of the Configure feature (as well as the Assemble feature).
In addition, refer to the Example: Configuring Joints Help section for an example of the use of the tool.
Note:The option is not supported for Joints scoped as a .
The option on the Context tab locks the changed assembly for use in the subsequent analysis.
The triad position and orientation may not display correctly until you click the option.
The option on the Context tab restores the assembly to its original configuration from DesignModeler or the CAD system.
It is suggested that you consider the following:
Renaming the joint objects based on the type of joint and the names of the joined geometry.
Display the Joint DOF Checker and modify joint definitions if necessary.
Create a redundancy analysis to interactively check the influence of individual joint degrees of freedom on the redundant constraints.
Configure and Assemble Tools Notes
The Configure and Assemble tools are a good way to exercise the model and joints before starting to perform a transient analysis. They are also a way to detect locking configurations.
The Assemble tool performs the assembly of the model, finding the closest part configuration that satisfies all the joints.
The Configure tool performs the assembly of the model, with a prescribed value of the angle or translational degree of freedom that you are configuring.
For the Assemble tool, all the joints degrees of freedom values are considered to be free. For the Configure joint, the selected DOF is considered as prescribed.
In both cases, the solver will apply all constraint equations, solve the nonlinear set of equations, and finally verify that all of them are satisfied, including those having been considered as being redundant. The violation of these constraints is compared to the model size. The model size is not the actual size of the part – as the solver does not use the actual geometry, but rather a wireframe representation of the bodies. Each body holds some coordinate systems – center of mass, and joint coordinate systems. For very simple models, where the joints are defined at the center of mass, the size of the parts is zero. The violation of the constraint equations is then compared to very small reference size, and the convergence becomes very difficult to reach, leading the Configure tool or the Assemble tool to fail.