week-11 Joint creation and Demonstration

Objective:

To create the different types of joints like translational, revolute, cylindrical, and spherical joints. The different types of joints are created between two rigid bodies using the keyword *CONSTRAINED_EXTRA_NODES and between two deformable bodies using *CONSTRAINED_NODAL_RIGID_BODY.

Cylindrical Joint:

A cylindrical joint is two degrees of freedom kinematic pair used in mechanisms. It provides a single-axis sliding function as well as a single axis rotation, providing a way for two rigid bodies to translate and rotate freely.

This joint is derived from the rotational joint by relaxing the constraints along the centerline. This joint admits relative rotation and translation along the centerline

Procedure :

Joint with Two Deformable-body

• The Two parts for cylindrical joints are created using Shape Mesh with Shell Cylinder and assigned with Shell section and material properties (*MAT_ELASTIC) to the parts

• CNRB is created for the outer cylinder (i.e Fixed part) and the master node for the first CNRB is created at the center of the cylinder
• Create a second CNRB for the inner cylinder(Moving part) but make sure the master node of the second CNRB coincide with the first CNRB which is created for the Outer cylinder

• The second pair of CNRB has created again for the outer and Inner cylinder with two coincide master node

• The cylindrical joint is created using *CONSTRAINED_JOINT_CYLINDRICAL card with nodes N1 and N2 has the two master nodes for the First pair of CNRB for Inner and Outer Cylinder and nodes N3 and N4 has the two master node for the second pair of CNRB for Inner and Outer Cylinder.

• The initial velocity of 10 mm/ms is assigned to Inner Part in the X-axis.
• And default control card to run a simulation is created

Results

Joints with two Rigid Bodies

• The Two parts for cylindrical joints are created using Shape Mesh with Shell Cylinder and assigned with Shell section and material properties (*MAT_RIGID) to the parts
• For the rigid body joint creation, we are going to use *CONSTRAINED_EXTRA_NODES
• First, four nodes are created at the centreline of the cylinder where the nodal pair 321,324 and 322,323 coincide with each other. A node-set created where nodes 321and 324 grouped to fixed one and 322 and 323 grouped to moving body. Further nodes of moving and fixed bodies are assigned to the particular part using the *CONSTRAINED_EXTRA_NODES_SET.
• The cylindrical joint is created using *CONSTRAINED_JOINT_CYLINDRICAL card with nodes N1 and N3 of the inner part and nodes N2 and N4 of the outer part.

• The initial velocity of 10 mm/ms is assigned to Inner Part in the X-axis.
• And default control card to run a simulation is created

Result

Translational Joint:

A Translational joint provides a linear sliding movement between two bodies.

This is a cylindrical joint with the third pair of off-centerline nodes which restrict rotation. Aside from translation along the centerline, the two rigid bodies are stuck together.

Procedure :

Joint with Two Deformable-body

• The Two parts for Translation joints are created using Shape Mesh with Shell Box and assigned with Shell section and material properties (*MAT_ELASTIC) to the parts

• CNRB is created for the outer Box (i.e Fixed part) and the master node for the first CNRB is created at the center of the Box

• The second pair of CNRB has created again for the outer and Inner Box with two coincide master node with the First pair of CNRB

• The third pair of CNRB is Created for the outer and Inner Box with an offset from the Centerline of the box but the two master node from the third pair has to coincide each other

• The Translation joint is created using *CONSTRAINED_JOINT_TRANSLATIONAL card with nodes N1, N3, and N5 of Inner box and nodes N2, N4, and N6 of Outer box

• The initial velocity of 10 mm/ms is assigned to Inner Part in the X-axis.

• And default control card to run a simulation is created

Results :

Joints with two Rigid Bodies

• The Two parts for Revolute joints are created using Shape Mesh with Shell Box and assigned with Shell section and material properties (*MAT_RIGID) to the parts
• For the rigid body joint creation, we are going to use *CONSTRAINED_EXTRA_NODES
• First, four nodes are created at the centreline of the box and two nodes are created slightly offset from the centerline
• where the nodal pair N1, N2 are coinciding and N3, N4 coincidings with each other the first and second pair of nodes are aligned with the centreline of the box.
• The third pair N5, N6 are coinciding with each other but there are not aligned with the first and second pair they are slightly offset from the centreline
• The nodes N1, N3, and N5 are constrained to the Inner part and nodes N2, N4, and N6 to the Outer part using the *CONSTRAINED_EXTRA_NODES card.

• The Translation joint is created using *CONSTRAINED_JOINT_TRANSLATIONAL card with nodes N1, N3, and N5 of Inner box and nodes N2, N4, and N6 of Outer box

• The initial velocity of 10 mm/ms is assigned to Inner Part in the X-axis.
• And default control card to run a simulation is created

Results:

Revolute Joint:

A revolute joint is one degree of freedom kinematic pair used frequently in mechanisms and machines. The joint constrains the motion of two bodies to the pure rotation along a common axis.

Nodes 1 and 2 are coincident; nodes 3 and 4 are coincident. Nodes 1 and 3 belong to rigid body A; nodes 2 and 4 belong to rigid body B. The relative motion of the two rigid bodies is restricted to rotations about the axis formed by the two pairs of coincident nodes. This axis is labeled the “centerline”.

Procedure :

Joint with Two Deformable-body

• The Two parts for Revolute joints are created using Shape Mesh with 4N and assigned with Shell section and material properties (*MAT_ELASTIC) to the parts

• CNRB is created for the Right plate (i.e Fixed part) and the master node for the first CNRB is created at the Midpoint of two plate

• Create a second CNRB for the Left plate (Moving part) but make sure the master node of the second CNRB coincide with the first CNRB which is created for the Right plate

• The second pair of CNRB has created again for the right and left a plate with two coincide master node and aligning with the first pair of CNRB

• The Revolute joint is created using *CONSTRAINED_JOINT_REVOLUTE card with nodes N1 and N3 has the two master node for the First pair of CNRB for Right and Left Plate

and nodes N2 and N4 has the two master node for the second pair of CNRB for Right and Left Plate

• SPC is created and all the DOF for the right plate nodes are constraint

• Boundary prescribed motion a node on the left plate along Z-axis

Results:

Joints with two Rigid Bodies

• The Two parts for Revolute joints are created using Shape Mesh with 4N and assigned with Shell section and material properties (*MAT_RIGID) to the parts
• For the rigid body joint creation, we are going to use *CONSTRAINED_EXTRA_NODES
• First, four nodes are created at the Midpoint of the Plate
• where the nodal pair N1, N2 are coinciding and N3, N4 coincidings with each other the first and second pair of nodes are aligned with the centreline of the box.
• The nodes N1, N3are constrained to the right plate, and nodes N2, N4, and are left plate using the *CONSTRAINED_EXTRA_NODES card.

• The Revolute joint is created using *CONSTRAINED_JOINT_REVOLUTE card with nodes N1 and N3 has the two master node for the First pair of CNRB for Right and Left Plateand nodes N2 and N4 has the two master node for the second pair of CNRB for Right and Left Plate

• SPC is created and all the DOF for the right plate nodes are constraint
• Boundary prescribed motion a node on the left plate along Z-axis
• And default control card to run a simulation is created

Result

Spherical Joint:

A spherical joint is used for allowing free rotation in two planes at the same time while preventing translation in any direction, including rotating in those planes.

The relative motion of the rigid bodies is constrained so that nodes that are initially coincident remain coincident. In the above figure the socket’s node is not interior to the socket—LS-DYNA does not require that a rigid body’s nodes be interior to the body.

Procedure :

Joint with Two Deformable-body

• The Two parts for Spherical joints are created using Shape Mesh with Sphere Shell and assigned with Shell section and material properties (*MAT_ELASTIC) to the par
• CNRB is created for the Half Sphere Part (i.e Fixed part) and the master node for the first CNRB is created at the Midpoint of Sphere

• Create a second CNRB for the Full Sphere plate (Moving part) but make sure the master node of the second CNRB coincide with the first CNRB which is created for the Half Sphere

• The Spherical joint is created using *CONSTRAINED_JOINT_SPHERICAL card with nodes N1 from the master node of half-sphere and N2 from the master node of the full sphere

• The initial rotational velocity of 20 mm/ms is assigned to Full Sphere along in the X, Y, Z-axis.

Results:

Joints with two Rigid Bodies

• The Two parts for Revolute joints are created using Shape Mesh with 4N and assigned with Shell section and material properties (*MAT_RIGID) to the parts
• For the rigid body joint creation, we are going to use *CONSTRAINED_EXTRA_NODES
• First, Two nodes are created at the Centre of the Sphere
• where the nodes N1, N2 are coinciding with each other the first
• The nodes N1 are constrained to the Half Sphere, and nodes N2 are constrained to the Full sphere using the *CONSTRAINED_EXTRA_NODES card.

• The Spherical joint is created using *CONSTRAINED_JOINT_SPHERICAL card with nodes N1 from the master node of half-sphere and N2 from the master node of the full sphere

• The initial rotational velocity of 20 mm/ms is assigned to Full Sphere along in the X, Y, Z-axis.

Result