RADIOSS Interfaces & Study of Effect of Notches

RADIOSS INTERFACES & STUDY OF EFFECT OF NOTCHES

AIM:

1. To mesh the bumper assembly with 6mm size.
2. To apply interfaces with different cases as prescribed, compare the outcomes of these cases and to Study the behavior of tube by modifying the notches as prescribed below.

PROCEDURE:

1. Import the given bumper model to Hypermesh and mesh the parts with 6mm mesh size.

2. Assuming Min. element length as 3mm and Max. as 8mm check for quality.

Fig: Finished model.

Case -1 : Crash tube model (Default parameters)

1. Import the model in to Hypermesh and Run the Radioss analysis without changing any parameters and plot the results.

Fig: Imported model.

Results:

Fig: Displacement.

Fig: Von mises stress.

Fig: Contact forces.

The maximum displacement for the model was found to be 280mm

The maximum von mises stress for the model was found to be 0.6949 kg/mm2

The contact force was found to be 93.78 KN

Fig: Internal Energy and Contact Energy.

The internal energy of the model increases linearly as shown in figure. The contact energy at initial stage will be very low and increases as the deformation increases which in turn increases the internal friction thus results in the increase if contact energy.

Fig: Rigid wall forces.

The resultant normal force at its maximum when the whole tube is deformed to its maximum value and then the force reduces as after the plastic deformation of the tube.

Case-2 : Crash tube model changing Inacti - 6

1. Import the given model in Hypercrash application and change the Incati – 6 in the Type 7 Interface as shown.

2. Delete the unsupported cards and export the model and run it in Radioss for analysis.

Fig: Changing of Inacti.

Results:

Fig: Displacement.

Fig: Von mises stress.

Fig: Contact forces.

The maximum displacement for the model was found to be 280mm

The maximum von mises stress for the model was found to be 0.7354 kg/mm2

The contact force was found to be 93.78 KN

Fig: Internal Energy and Contact Energy.

The internal energy linearly increases with the deformation.The contact energy will be at its maximum when the tube is completely deformed and after that the energy will reduces to a constant value.

Fig: Rigid wall forces.

The rigid wall forces are similar to that of the previous simulations of the crash tube model.

Case:3 Crash Tube With Type- 11 Interface

1. Import the previous model in to Hypercrash and create a new interface of Type 11 along with type 2 and Type 7 as shown.

2. Enter the recommended parameters for type 11 and Select components as both slave and master.

3. Enter gap min as 0.95mm (slightly less than Type 7). Delete the unsupported cards and Export the model.

Fig: Type 11 Interface.

4. Run the model in the radioss profile for analysis.

Result:

Fig: Displacement.

Fig: Von mises stress.

Fig: Contact forces.

The maximum displacement for the model was found to be 279.9mm

The maximum von mises stress for the model was found to be 0.6694 kg/mm2

The contact force was found to be 69.75 KN

Fig: Internal Energy and Contact Energy.

The internal energy increases linearly as the deformation increases. The maximum contact energy is lesser in Type 11 when compared to the maximum contact energy of in Type 7 contact interface.

Fig: Rigid wall forces.

When compared with the results of Type 7 the resultant tangent forces are higher in Type 11.

Case : 4 Crash tube with no notch and no boundary condition on rigid body

1. Import the previous model in to Hypercrash and open boundry condition of rigid body. Uncheck all the DOFs given (Translation and rotation X,Y,Z) and export the model.

Fig: Boundry Conditions.

2. Import the same model in to Hypemesh and align the nodes so that the notches are removed and plain face is obtained as shown in figure. Run the analysis for the model.

Fig: Finished model.

Result:

Fig: Displacement.

Fig: Von mises stress.

Fig: Contact forces.

The maximum displacement for the model was found to be 279mm

The maximum von mises stress for the model was found to be 0.6476 kg/mm2

The contact force was found to be 60.93 KN

Fig: Internal Energy and Contact Energy.

The internal energy increases linearly with the load and deformation. Since there is no notches the contact energy is lesser compared with the previous cases.

Fig: Rigid wall forces.

The maximum resultant normal force is bit lesser than the previous case since there is no notches there by reduces the stress.

Case: 5 Crash tube with center notch.

1. Import the previous model and create a notch at the center of the tube by aligning the nodes as shown in figure.

2. Run the analysis with same parameters of case-4.

Fig: Finished model.

Results:

Fig: Displacement.

Fig: Von mises stress.

Fig: Contact forces.

The maximum displacement for the model was found to be 281.2mm

The maximum von mises stress for the model was found to be 0.6323 kg/mm2

The contact force was found to be 76 KN

Fig: Internal Energy and Contact Energy.

The internal energy increases linearly with deformation.The maximum contact energy is higher than the case 4 because of the notch at the center of the tube.

Fig: Rigid wall forces.

The maximum total resultant force is higher than the case-4 since the notch increases internal energy thus increase in the rigid wall force.

Case: 6 Crash tube with opposite face notches.

1. Import the previous case model in Hypermesh. By aligning the nodes remove the notches from the 2 opposite sides thus making notches on the other opposite side as shown below.

2. Run the analysis without changing any parameters.

Fig: Finished model.

Result:

Fig: Displacement.

Fig: Von mises stress.

Fig: Contact forces.

The maximum displacement for the model was found to be 277.8mm

The maximum von mises stress for the model was found to be 0.6624 kg/mm2

The contact force was found to be 75.56 KN

Fig: Internal Energy and Contact Energy.

The internal energy increases linearly with the load. The contact energy is slightly lesser than the previous case since the notches are only in 2 sides thus reduces the energy.

Since the notches are of 2 sides, the maximum total resultant force is lesser than the previous case.

Result Comparison: Contact Interface

Case	Displacement	Von Mises stress	Contact force	Internal Energy	Contact energy	Total Resultant Force
1 (Type 3&7)	280	0.6949	93.78	430000	2000	1300
2 (Type 3 & 7) Inacti-6	280	0.7354	93.78	430000	2000	1300
3 (Type 3, 7 & 11)	280	0.6694	69.75	430000	1800	1300

Result Comparison: Notches

Case	Displacement	Von Mises stress	Contact force	Internal Energy	Contact energy	Total Resultant Force
4 (No Notches)	279	0.6476	60.93	430000	1200	1100
5 (Center Notch)	281.2	0.6323	76	430000	1700	1300
3 (2 opposite faced notch )	277.8	0.6624	75.56	430000	1250	1300

CONCLUSION:

1. By comparing the obtained result for different cases of contact interface the case -3, combination of Type 7 and 11 gives the accurate result since the stress value is lesser and accurate without changing its displacement values.
2. The tube without any notches undergoes deformation without any hindrance due to which the contact force and energy are lesser. The resultant forces are slightly lesser because of absence of notch reduces the internal friction on nodes.
3. The center notched tube undergoes huge deformation with maximum displacement with minimum stress value compared to the other cases.
4. The 2 sided notch makes the tube slightly rigid because the displacement values are lesser than the other 2 cases but the stress value is bit higher than the other 2 cases.

Thus we can conclude that the combination of type 7 and 11 gives accurate results and by changing the notch position and location will affect the performance parameters of the tube.

Model

https://drive.google.com/file/d/1WzmPdS4-v5pZbt7ILgBhVeUD1P1Y3ijk/view?usp=sharing