Assignment 6

OBJECTIVE:

To check and create the properties of a Neon Frontal Crash model and to create the required output requests using Hypermesh and Hypercrash and verify the results for the same using Radioss - Hyperview - Hypergraph 2D.

CASE SETUP & EXECUTION:

• Primarily the Hypercrash is opened and a proper unit system is chosen. Here, kN, mm,kg,ms unit system is chosen.
• The contact interfaces are checked for their recommended parameters. The existing contacts are deleted and a new global contact is created with the following parameters.

TYPE 7 Contact Interface:

Istf = 4

Igap = 2

Idel = 2

Stfac = 2

Stmin = 1

Gapmin = 0.5

Inacti = 6

Fric = 0.2

Iform = 2

• The already created rigid bodies are checked if any errors are there in the model. Any issues with the rigid bodies are rectified. Here in this model there are no issues.
• Next a rigid wall is created with Dsearch = 1000, sliding is set to sliding with friction and friction = 0.1. The normal is defined in the negative X-direction.
• While creating the rigid wall, it is made sure that it does not penetrate into the elements or the nodes.
• An initial velocity is created for 35mph which is converted mm/ms that is around 15.64.
• The engine run file is made to run for 80ms.
• Next the timestep is maintained between 0.5 to 0.1 ms.
• After this mass balancing is done so that the total mass comes to 700kg. This is done my adding some mass in the places where the passengers will sit and the mounting for the dashboard with the gears and systems.
• Then the output blocks are created.A section is created on the rail on the node 174247 to check the forces on this rail.
• Another output for checking the axial forces is created on the rails. The forces which come from the bumper to the rails is checked.
• Next a cross section is created on the bumper as a shotgun to check the forces acting on it when the car is crashed.
• Then another cross section is created on the A Pillar of the car to determine the stress and deformation which occurs during the crash.
• For defining the cross sections, first the component on which the section needs to be created is selected. Then the base node is selected based on the node ID or a random node. After that the normal is defined.
• An Accelerometer is defined at the base of the B Pillar to determine the acceleration curve in the output.
• For the accelerometer a node from the base of B Pillar is selected. And the time frequency is given to be 5.
• Intrusions on the dash wall on two specific nodes 66695 and 66244 are to be deteremined in the output.
• A seperate skew for each node is created in order to define the system while creating an output request for the intrusions.

RESULT:

OUTPUT REQUESTS:

Sectional Force in the rails on the node 174247 –

• The maximum force received on the rail components is about 17KN at 58ms. The least force is 3.8KN at 38ms. The node 174247 on the rails receives a large deformation around 55-62ms and gradually towards 80ms the forces are reduced.

Shotgun Cross Sectional Forces –

• The above plot shows the shotgun cross sectional forces. From this graph we can see that the maximum force on the shotgun is 12KN at 46ms. After this we can see a sudden fall in the force and gradually fluctuates towards 80ms. The shotgun is created on the bumper and you can see that this force 12KN is comparatively lesser than the force received on the rails which is 17KN.

A-Pillar Cross Sectional Forces –

• From the above plot we can see that the A-Pillar constantly receives a maximum force of more than 2KN at around 37ms. There is a drop in the force and the minimum force acting on the pillar is 0.26KN at 53ms. After this also we can see a rise in the forces to more than 2KN.

Acceleration Curves on B-Pillar –

• The two acceleration curves shows that the acceleration is maximum around 30ms to 50ms and the velocity gradually decreases towards the end 80ms.

Intrusions on the dash wall at nodes 66695 and 66244 –

• From this graph we can see that the intrusions on 66244 is 260mm and on the node 66695 is 250mm. The lower the intrusions the lesser will be the damage or impact on the car.

Energy Curves:

• Here we know that the Kinetic energy gets converted to Internal energy. So as the kinetic energy is reducing through the impact, the internal energy is increasing. This means that the car has absorbed a good amount of energy so that the impact is less on the passengers.

CONCLUSION:

Mass Error	Energy Error	Von Mises	Displacement
0.001 - 0.005kg	0.3%	0.435	1251mm

• Seeing the above results we can say that the impact is equally distributed through the body and it is not centered to full impact on the bumpers.

• The amount of energy absorbed is high so the elements deformed will be less. This increases the safety of the car.

• Hence the Neon Frontal Crash model was successfully run and analysed using Hypermesh - Hypercrash - Radioss - Hyperview - Hypergraph 2D.

The ZIP file of the model animation files are attached in the following link.

https://drive.google.com/file/d/17TsglK_q4lzjbx9-kNd883MkJamBDCpc/view?usp=sharing