week-11 Joint creation and Demonstration

Aim: To create different joints such as revolute, cylindrical, spherical and translational using ls dyna.

Procedure:

Creating Revolute Joint:

Revolute joint is one degree of freedo kinematic pair mostly used in mechanism and machines.

• To create revolute joint, open ls prepost and create shell mesh. Go to mesh >> shape mesh >> Entity: 4Nshell >> Create.

• Material and section is to be defined and assigned to the above parts.

• Create 4 nodes between the two parts and renumber in such a way 501,503 coincides and 502,504 coincides.

• Now create extra node set and assign the nodes 501, 502 to part 1 and 503,504 to part 2.

• Constrainig the nodes of one end of the shell mesh.

• Assigning boundary conditions to the shell.

• Assigning run time.

• Run the analysis.

Results:

Creating Spherical Joint:

A spherical joint is used for allowing free rotation of in two planes at the same time.

• To create a Spherical joint, create a one sphere and one hemi sphere with larger diameter using the shape mesh option present in element tools.

• Creating section and materials cards and assign it to the respective parts.

• Creating CNRB set at the outer edge for the hemi sphere and for entire nodes for sphere.

• Creating Spc set.

• Creating displacement for the sphere.

• Creating Spherical Joint.

• Creating run time.

• Save the model and run the simulation.

Results:

Creating Cylindrical Joint:

A cylindrical joint is two degree of freedom kinematic pair used in mechanisms. It provide single axis sliding motion and rotates along it's own axis.

• To create a cylindrical joint, go to element tool >> shape mesh >> cylinder.

• Creating material and section cards for the cylinders and assigining to the parts.

• Creating CNRB at the outer edge of the cylinder.

• Creating Cylindrical joint.

• Creating Spc set.

• Assigning the displacement to the cylinder.

• Creating the run time for the simulation.

• Save the model and run the simulation.

Results:

Creating Translational joint:

A translate joint has one degree of freedom which is sliding moment between the bodies along its own axis.

• To create a translational joint, go to element tools >> shape mesh >> shell box.

• Creating section and material card and assiging to the parts.

• Six nodes are created to define the translation joint. Nodes are renumbered into 3000, 3001, 4000, 4001, 5000 and 5001.

• Creating Spc set.

• Creating Extra node set for nodes with id 3000, 3001, 4000, 4001, 5000 and 5001. Assiging 3000, 4000 and 5000 nodes to part 1 and 3001, 4001 and 5001 to the part 2.

• Assigning rigid body motion.

• Creating timestep card for more stability.

• Assigning run time for the simulation.

• Save the model and run the simulation.

Results:

Conclusion:

• Different kind of joints are created between two rigid bodies and two deformable bodies.
• If a joint is created between two rigid bodies then Extra Node Set is used and for deformable bodies Constrained Nodal Rigid Bodies are used.