Assignment 5
OBJECTIVE: 1. To mesh the given bumper model in hypermesh with the target element length to be 6mm.
2. To Perform simulation on a crash tube Model using Radioss.
SOFTWARE USED: Radioss and hypermesh.
PROCEDURE:
1. Open hypermesh and load the document in hypermesh workspace.
For this model we need to create a mesh and then add 1D elementrts in the form of connections to it. For the mesh we have used a mixed type and we have added 1D connections as spot welds on various points in the model.
Figure 1: Beam Mesh
Figure 2: Crash Box Mesh
Figure 3: Full Body Mesh
Figure 4: Spot Weld Connections
2. Now we need to import the Crash beam file provided to us. We will perform 6 simulations as different cases and different changes in the model.
CASE 1
For this case we neeed to run the Model as it is using RADIOSS and then view the results in hyperview.
Figure 5: Imported Crash Tube Model
Figure 6: Internal and kinetic Energy plots
As we can see here that the internal energy rises upto a value of about 4000mj. We can observe that both the kinetic and internal energy have a same behavior when the simulations starts. As the crash tube model starts at rest it has not internal energy released but due to the movement at a particular direction it has attained a certain velocity which decreases as the simulation is run till the end.
Figure 7: Tangent Force
Figure 8: Normal Force
The maximum tangential force is vey low as compared to the Normal force. This is due to the direction of the velocity and the deformation. The normal force on the other hand has a value as high as 1350 N.
CASE 2:
Figure 9: Internal Energy and Kinetic Energy plot
As we can see that there is not much difference in the internal and kinetic energy from case 1 after changing Iacti to 6.
Figure 10: Rwall Forces
We can observe that after changing Inacti the normal force has decreased and matches with the tangential force to an approximate level as compared to case 1.
Figure 11: Contact Energy Case 2
We can observe from case 1 that the contact energy in case 2 has increased after increasing Inacti to 6. this is due to the penetration gap which is kept constant at the latter stages of the simulation.
CASE 3:
In this case we change the type of contact to type 11 and run the simulation. Type 11 conatct is a edge to edge conatct between the master and the slave component.
Figure 12: Type 11 Properties
Figure 13: Internal and kinetic Energy for case 3
We can observe that the inetrnal energy has dropped some amount as to the contact change in the simulation.
Figure 14: Normal and tangential force
We can see here that the normal force has increased as compared to the case 2 and similarly the tangent force has decreased.
Figure 15: Contact Energy Plot
CASE 4:
In this case we have removed the notches of the model and remove the boundry conditions from the rigid body node.
Figure 16: Notches Removed from the Model
Figure 17: Internal and kinetic energy
As we can see that the internal and kinetic energy have increased in this case as there is no boundry condition and no notch in the model.
Figure 18: Contact energy case 4
We can also observe that the contact energy from the master to the slave component is decreased in this case.
CASE 5:
Figure 19: Middle Notch Created
In this case we need to create a middle notch and check the simulation with the same parameters.
Figure 20: Kinetic and Internal Energy
We can observe that the notch has resultred in decrease of the internal and kinetic energy. as we have also observed in the previous cases.
Figure 21: RWall Forces
We can observe that the Rwall forces have decreased from the previous simulation. The tangential force has reduced significantly and as for the internal energy we observe a small amount of decrease.
Figure 22: Contact Energy
Here we can observe an increase in the contact energy due to the addition of notches between the interface of the components in type 11 Contact.
CASE 6:
In this case we apply a notch in opposite faces on any of the faces in the model.
Figure 22: Internal and kinetic energy for case 6
Figure 23: Normal and tangential force
Figure 25: Contact Energy for case 6
For case 6 we can clearly see an increase in the internal and kinetic energy. This is because the notches are not continous in the model and are only on a small part of the faces of the model.
We can also observe that the contact energy has increased as compared to case 5. While in the simulation it has also been observed that the internal energy and kinetic energy have increased as compared to the previous case.
RESULTS AND CONCLUTIONS:
We can observe many changes in the models with different types of parameters. We have also observed that the energies have changed due to the changing of notches. This is due to the fact that the notches coarsen the mesh on that particular area which generally caused loosening of the solid particles. This results in decreasing in the internal, Kinetic and contact energy in the models whenever notches were reduced or removed. Due to Increase in number of notches, the stresses also increase and thus the energy ini the model aslo increases as compared to when notches are removed.
As far as the cases are concerned, case 2 is the best model for this crash tube analysis as the contact energy is the highest from all the cases and we observe a minimum energy error.
NOTE: The files with the videos of animations are uploaded in the following link
https://drive.google.com/drive/folders/1sHblBqsa24eVvxVMvw99X93p9o5ifTbH?usp=sharing