week-11 Joint creation and Demonstration

Aim: Using the manual (*CONSTRAINED_JOINT keyword) demonstrate spherical, revolute, cylindrical, and translational joints between two rigid bodies.

Procedure:

1. Revolute joint:

As we can see in the theory, initially, we created two 4N shell elements using shape mesher, in my case both were of equal dimensions (not compulsory), Some space was kept between them.

Then using elements-create node: 4 nodes were created where 2 pairs were coincident as we can see in the above picture.

Now, create set was done and node set was created such that among the coincident nodes in each set we have one node (for example with reference to the above picture, i would create two node set id (one set of node 1 and 3 and another set of 2 and 4)

Now, We have to assign the node set to the relevant parts , for this we used constrained extra node sets, and created the set by defining the part id and the node set id , as our motive is to assign one node set id to one part(red part) and another node set id to the other part(blue)

Now, the constrained joint revolute was created where we made sure that N1 and N3 belong to body Red and N2 and N4 belong to body blue.

Now, Boundary condition is defined by using boundary spc for the required nodes in a body that i want to keep fix and prescribed motion to a node in the other body which would be provided displacement.

the displacement curve and the boundary condition are shown below.:

Control Termination of dt =1 and Database D3plot of dt=0.1 is assigned. (this would remain same for all the joints).

Control Timestep card is used, with LCTM curve as shown below, for more stablity we assign smaller time steps

Thus, the simulation is run. (The video is attached in the submission)

Spherical joint:

The setup shown above is created by mesh shaper, we can see a rigid box and a rigid sphere, now our methodogy is similar, we have to create 2 sets that coincide, and then use constrained extra node set to assign the node set to the proper PID and then create the constrain joint sphere with the correct node numbering one in the sphere part and other in the box.

Initail velocity rigid body is used to assign rotational motion to the sphere.

All the other termination. control timestep, d3plot cards are as same as revolute.

The files are attached in the submission.

Cylindrical:

Here two first two cylindrical shapes of different radius but same centre are created using shape mesher.

Then again similar to revolute joint, I define 4 nodes (2 coinciding pairs), one node of each pair is then assigned to each cylindrical parts using constrained extra node sets, and then for the boundary condition, the red cylinder is constrained in all direction using spc boundary card and the the blue cylinder is giving initail velocity card with translational along x axis and rotation around the same axis. Then the constrained cylindrical joints card is used to assign the respective nodes, the methodoly was same as revolute.

All the other termination. control timestep, d3plot cards are as same as revolute. .

The video and files are attached,

Translational joint: Just for simplicity i took the same geomertry as was used in the cylinder (one may also do it with box shapes).

Here, the principle of using constraint extra node set for the coinciding pairs are same but with a minute change.

In this case, we have 3 pair of nodes, 2 pair of coinciding nodes in the same central axis, and one offset pair is used in order to restrain the rotation, here for this extra node set, Constrained extra nodes_node card is used where one of the node if this offset pair is assigned to each body. and for the other two set the constrained extra node set card is used wth previous methodology as revolute.

And then constrained joint translational card used using where all the 6 node id are assigned, with N5 and N6 consisiting of one node each of the offset pairs and for N1-N2 has the coinciding nodes and N3-N4 have another coinciding nodes.

All the other termination. control timestep, d3plot cards are as same as revolute. .

The video and files are attached,