Comparing the effect of TYPE-7 interface parameters, TYPE-11 along with TYPE-7 interface, and effect of notches in the crash box.

Model setup Case:1 and Case:2

The models used in these cases are same but the only changes were made in the Interface i.e,

In Case:1 the parameters are set to the default value,except Istf=3.

• The model was made to run as it is with default interface parameter.
• There are some initial Penetration in the model, these are controled using the parameters available in the Interface.
• Since in Case:1 the Inacti = 0 is selected there were no actions taken for the initial penetration in the model.

In Case:2 the parameters are set to the recommmended values. The Igap=3,Idel=2,Fscale_gap=0.7,Stmin=1KN,Fric=0.2,Gapmin=0.5,Inacti=6,Iform=2.

• The model was made to run with the recommeded inteface parameters.
• The initial penetrations were again not cleared and was controled through the interface parameters.
• The Inacti=6 is set to reduce and scale the gap between the master and the slave segments.

Comparision:

• In case:1, since the Inacti=0 is set there were no actions taken for the penetration in the model.
• So there were no energies used for the penetrations correction by the Inacti alogrithm.

• In case:2, since Inacti=6 were set, the slave nodes that were penetrating into the master segment gap were pushed out of the gap region.
• The force used for pushing the penetrating slave nodes out of the master segment gap region results in the negative energy error.

The energy error in Case:2 started earlier when compared to Case:1, because the Inacti alogorithm have started using some energy to push the slave nodes out of the master segmenty gap.

This can also be seen clearly by plotting the Internal energy and the contact force of this 2 cases.

The contact energy in case:2 is higher than case:1, because in case:2 additional energy is used for penetration correction. This is relfected in the internal energy as well, since the contact energy in case:1 is lesser the remaing energy is compensated in the Internal energy. Similarly in case:2 the increase in the contact energy is compensated in the decreased internal energy.

So this change in the contact energy becomes the reason for the change in the internal energy.

When compared the Total Energy between these two cases there is a dip in the Case:2, this is also due to energy used for the penetration correction.

Case:3 Type 11 contact:-

The type 11 contact is a edge to the surface contact where it comes in to eliminate the limitatations of type 7 contact. This combination of type 11 and type 7 contact should be used in critiacal situations since the solver has to slove some complex mathematical equations. Sloving this might cause a huge delay in the simulation.

Inspite of taking care of the Penetration in the surface and in the edges the Case 2 manages to keep the contact energy low is because of the TYPE 11 contact alogorithm that helps in remove the penetrating nodes with less energy when compared to the Case 1.

Accordingly, there is a fluctuation in the Internal Energy of the both cases.

CASE STUDY: CRASH TUBE & NOTCHES

The objective of the Crash tube is to observe energies as much as it could so that the rest of the stucture experiences less force during the impacts.

In this we have three different crash tubes, one with no notch and others with notches displaced.

So inoder to find out how much energy did each of these crush tube have obsorbed, the internal energy of these tubes are studied.

From the Internal Energy graph of these three cases, it is clear the tube without the notches absorbs more energy during the impact.

So, the no notch tube is more suitable for the crash applications.