Assignment 5

Objective:

1. To learn different type of contacts in surface interfencing by Node to node, Edge to node and Edge to edge in either shell elements or 3D bodies.
2. To learn energy error corelation with contact asignment.
3. To learn various interface tool implication on body such as Invel, Inacti6 and presence of Notching.

Default & Inacti 6:

Default Crush Tube Model:

• Imported the model with two notches at side ends.
• Default two contacts were provided ie Type 2 & type 7.
• Ran the model & got the results in Hyperview for contact force & various energies.
• Energy error in engine file was found to be -3.8%.
• 

Inacti =6 case:

1. Same previous Crush tube model importd.
2. Made a change in Inacti = 6 in Type 7 contact by keeping all other conditions as it is.
3. Ran the model & got the results in Hyperview for contact force & various energies.
4. Energy error in Engine file was found to be -5.4%.

Result & Discussion:

Inacti = 6 helps in realignment of the nodes which which were penetrating within contacting surfaces.

In this process the node which is being penitrated is removed out by resistive force causing loss in energy error.

Thus Energy error has changed from -3.8% to 5.4%.

Type 11 Contact:

1. Imported the Crush tube model with Type 2 & 7 default contacts.
2. Created Type 11 contact between two mating panel.
3. Slave and master surfaces selected by component selection.
4. The recommended interface parameters were inserted such as Igap=2, Gapmin=0.5, Inacti=6, Istf=4, Stmin=1000, Idel=2, Iform=2 etc.
5. Ran the model & got the results in Hyperview for contact force & various energies.

Result & Discussion:

Type 11 contact is Edge to edge kind of contact. Internal energy increased by some ammount. As we increase the stiffness the contact force is reduced.Other energies remained same.

Notches:

Remove Both notches and Boundry condition of Crush tube:

1. By Nodal alignment removed the notches and made the geometry with planar sufaces.
2. In boundry condition tab, all 5 DOF were constrained except Z linear movement which changed to Zero DOF by unchecking all the boxes.
3. Invel had value of -13.3 m/s in Z direction.
4. Ran the model & got the results in Hyperview for contact force & various energies.

Middle Notch:

1. Created a Notch in the middle of the tube by nodal alignment.
2. By keeping all DOF and other parameters to default state ran the model.

End Notch:

1. Created a Notch in the end near Rigid wall section of the tube by nodal alignment.
2. By keeping all DOF and other parameters to default state ran the model.

Results & Discussion:

1. Collapse initiation found to be occurred in the notch section.
2. If there are more than one notch, then collapse was found to be begin from the bottom notch upto the top notch.
3. In the last case Notch was in direct contact with the rigid wall causing larger deformation and contact forces about 126.6N.

Bumper Meshing :