Assignment 6-Frontal Crash Simulation Challenge

Assignment 6:- Frontal Crash Simulation

Aim -

To run a simulation for the frontal crash [BIW] and to obtain a result in the post-processing.

Objective -

To check the unit system in the solver.

To create an appropriate interface, friction 0.2 and recommended parameters.

To check for the penetrations and intersections.

To create a rigid wall with friction 0.1.

To add extra mass to attain a target mass of 700 kg.

To apply initial velocity to the car.

To create sections and find sectional force in the Rails, Shotgun, and A-Pillar.

To create spring elements to get intrusions and to calculate the intrusions.

To create an accelerometer to calculate the acceleration of the car.

To create TH for all the inputs requested.

To run the simulation.

To plot the graphs in the post-processing.

 Procedure: -

1. Import the .rad file using the import solver.

 

 

 

2. Check the unit system in [ kg, mm, ms]

Now go and check for the unit system of the model, to check for the unit system, Go to the Model Browser >> Control Cards >>BEGIN_CARD.

 

 

3. Now go to the HyperCrash, Go to Menu Bar >> Applications >> HyperCrash.

 

Make sure whether the unit system in HyperCrash is [ kN, kg, mm, ms].

 

 

Now import the model in hypercrash, to import the model, Go to Menu Bar >> File >> Import >> Radioss.

 

 

 

4. Mass Balancing [ Adding Mass to the Model to get COG at Proper Position]:

1. Here the COG is not in a proper position. So we need to add mass to get COG at a proper position.

2. To Check the Mass and COG [Centre of Gravity], Go to HyperCrash Menu Bar >> Mass >> Balancing

 

 

 

The initial position of COG is shown below figure.

 

Now mass should be added to get COG in a proper position. It should be in the center of the cross member.

To bring COG to the center of the cross member, we should add a mass.

To add mass, Go to Load Case >> Added Mass.

 

Now right click on the added mass browser and select Type=1, Mass is distributed to each node of the node group.

 

 

The initial mass is 188 so we have to add 512 mass.

 

 

 

COG after providing mass.

 

 

Now export this file and save it in a specified location and import this model into hypermesh and check the total mass.

 

 

 Now import the exported model from HyperCrash to the HyperMesh.

 

 

 

 

Next, go and check in hypermesh, Whether we have attained 700 kg mass.

 

To check, Go to Menu Bar >> Tools >> Mass Details >> Mass, COG, Inertia

 

 

 

 

5. Create the Interfaces

Here for this model, TYPE 7 Contact Interface is created with the recommended parameters.

 

 

 

 

6. Check for the Penetration:

Here check for the penetrations, to check, Go to Menu Bar >> Tools >> Penetration Check.

 

 

 

7. Creation of Sections

 

 Here we must create a section, the section should be created at the node. To find we have to display the numbers in the display panel.

 

 

Select the node by id and enter the id number, The node number will be displayed, we must create a section there. 

 

 

 

Next for creating a section, we need a frame, so we need to create a frame first. To create frame Right-click on the Solver Browser >>Create >> Frame >> Mov.

 

 

Next, select the nodes to specify the location of the frame to be created on the model.

Switch to the created by node reference, Now selects the Node at Origin >> Node at Z-axis >> Node at YZ Plane.

 

 

Then create a section, to create a section, Right Click on the Solver Browser >> SECT >> SECT

 

 

 

After selecting the SECT to create a section, A parameter window will be opened left side. There will be Nodes (N1, N2, N3), Select the nodes to create a section.

 

 

Next Right Click on the grshell_id to select the elements, where we created the section.

Enter the values for deltaT and alpha.

Coefficient of filtering (alpha=0.67).

Time step for saving the data (deltaT=0.001).

 

 

 

 

Now we must check whether the section created for the rail component is fine or not fine.

If all the nodes get realized in the elements, then the section created for the rail component is fine.

One row of elements should be maintained.

To check Right-click on the Section in the Model Browser >> Review.

 

 

 

 

 

Similarly, we must create a section in the other side.

For that, create a temp node at 174247 nodes, translate the node to the other side and create a frame and section.

To create a temp node, Go to Geometry >> Temp Nodes >> Select the Node at the Required Location >> Add

Now translate that node to the other rail component.

To translate, Go to Tools >> Translate >> Select the Node and make it as duplicate and translate >> Switch to the Y-Axis >>Magnitude >> Translate -.

 

 

Do previous procedures for another side of the pillar.

 

 

 

All sections

 

..

8. Create Accelerometer at the Left-Pillar:

Here we have to create an accelerometer at the B-Pillar. To create an accelerometer, Right Click on the Solver Browser >>Accelerometer >>ACCE.

 

 

After creating the accelerometer, In the Accelerometer parameter window, we must specify the node ID.

To specify the node ID, first, we must create a node on the B-Pillar base component.

 

 

 

And then translate the duplicate node and create an accelerometer on another side.

 

9. Give the Initial Velocity of 35 mph

 

Here the initial velocity should be given, Cause the car should go and hit the rigid wall, so th initial velocity should be given.

To give initial velocity, Create INIVEL Control Card, to create Right Click on the Solver Browser >> Create >> Boundary Conditions>> INIVEL

 

 

After creating the INIVEL card, select all the components of the car, Cause the initial velocity should be given to the whole car, Cause the whole car should go and hit the rigid wall.

Expand the gmd_ID in the parameter window and select all the components.

 

Assign an initial velocity of 35mph,1mph=0.44704 m/s, =35x0.4470, =15.6464 m/s

 

 

 

Now translate and create the two temp nodes to the cross-member component's face.

 

Now create a spring, to create a spring element, Go to 1D >> Spring >> Select Node 1 and Node 2.

 

 

10. Create Rigid Wall with Friction 0.1:

 Rigid Walls allow the user an easy way to define an interface between a rigid surface and nodes of a deformable body.

A Rigid Wall is a non-yielding retaining wall that is defined by the user Master Node and a group of Slave Nodes.

Rigid Walls allow for an easy way to define an interface between a rigid surface and nodes of a deformable body.

To create Rigid Wall, Go to Solver Browser Right Click >> Create >> RWALL >> Plane

 

 

Next, the nodes should be selected to create a plane to define the rigid wall.

Next translate the node to 20mm, while translating the node make it a duplicate and translate it in X-Axis.

 Now select the node on the bumper to define the coordinates of the Temp node [XM, YM, ZM].

Enter the Direction of the Normal [-1, 0, 0].

The node selected to define the coordinate system

 

 

 

 

 

 

11. Request TH File for the Required Outputs and Give Time Step Value

Here the timestep should be assigned to the model to run the simulation.

The required values are to be entered in the ENG_DT_BRICK, ENG_DT_INTER, and ENG_DT_NODA control cards.

 

 

 

 

TH for Accelerometer-

 

First request TH for the Accelerometer, to request TH for Accelerometer, Right Click on the Solver Browser >> Create TH >>ACCEL.

 

 

 

Next at the bottom, there will be a window, there go to the Entity IDs option and select the accelerometers, A window will pop up, select all, and hit on ok.

 

 

 

TH for Interface:

Second request TH for the Interface, to request TH for Interface, Right Click on the Solver Browser >> Create >> TH >> INTER

 

 

 

TH for the Sections

 

Similarly create the TH for sections as created for previous case.

 

 

 

 

TH for the Intrusions (Springs):

Similarly, create the TH for Springs as created for the previous case.

 

 

 

12. Run the Simulation

 

Now run the simulation, to run the simulation, Go to Analysis

Go to Analysis Panel >> Radioss >>Run.

Check the Include Connectors, if there are any connectors in the model, The connectors will also be taken into account

 

Type -NT 4 in the options tab, this will make the simulation faster.

Where NT indicates No of threads,4 indicates assigning the task to 4 cores in the system.

 

 

 

After completing the simulation, the radioss will pop up a solver window stating Radioss Job Completed which indicates the simulation has been completed.

 

 

Now go and open the 00001.out the file with notepad.

 

 

HyperView allows for loading and viewing result files obtained from several sources.

Based on the solver type of the files and the results you would like to visualize and analyze, there are different ways to load the input deck and their corresponding results into HyperView.

First, begin the postprocessing in the Hypermesh.

Import the animation file .h3d into the HyperView.

 

 

 

 

Load the .h3d file.

 

 

Then select apply.

 

 

 

After importing the .h3d file into the GUI, Enable the contour.

The contour tool creates contour plots of a model graphically visualize the analysis results.

To enable contour, Go to Results Toolbar >> Contour.

 

 Now switch to the Von Misses Stress in result type and select the component, select the averaging method as simple and then click apply.

 

 

 

 

Check for the Intrusions:

After running the simulation, we have to check for the intrusions.

Note: The allowable intrusion is 15 cm.

To check for the intrusion, measure the distance between the springs where we created.

To measure, go to the measure tool from HyperView and select the end node of the springs to know the distance between them.

 

 

 

After defining the nodes at the end of the spring at the initial position before the collision, the magnitude for the spring at node 66695 is 737.127 mm.

 

 

After defining the nodes at the end of the spring after the collision, the magnitude for the spring at node 66695 is 616.613 mm.

 

Intrusion Results:

1. Spring [At Node 66695] = 737.127-616.613 = 120.514 = 12.0514 cm.
2. Spring [At Node 66244] = 760.153-708.684 = 51.469 = 5.1469 cm.

 

1. Plot the graphs using -Hypergraph 2D:

Now plot the graphs using Hypergraph 2D, we are plotting the graphs to see what is happening in the rail component.

Hypergraph 2D is a powerful data analysis and plotting tool with interfaces to many popular file formats.

It is a sophisticated math engine capable of processing even the most complex mathematical expressions.

Hypergraph 2D combines these features with high-quality presentation output and customization capabilities to create a complete data analysis system for any organization.

 

 

Left Rail:

The graph obtained for the Left Rail.

The maximum sectional force on the Left Rail is 33.4593 KN.

 

 

Right Rail:

The graph obtained for the Right Rail.

The maximum sectional force on the Right Rail is 11.4846 KN.

 

 

Left B-Pillar:

The graph was obtained for the Left B-Pillar.

The maximum sectional force on the Left B-pillar is 0.117727 KN.

 

Right B-Pillar:

The graph was obtained for the Right B-Pillar.

The maximum sectional force on the Right B-Pillar is 0.133742 KN.

 

 

Left Shotgun:

The graph obtained for the Left Shotgun.

The maximum sectional force on the Left Shotgun is 21.3684 KN.

 

Right Shotgun:

The graph obtained for the Right Shotgun.

The maximum sectional force on the Right Shotgun is 18.9963 KN.

 

 

Left Pillar Base Component Acceleration:

The graph was obtained for the Right B-Pillar Base Component Acceleration.

The maximum acceleration on the Left Pillar Base Component is 0.354568 m/s.

 

Right Pillar Base Component Acceleration:

The graph was obtained for the Right B-Pillar Base Component Acceleration.

The maximum acceleration on the Right Pillar Base Component is 0.270513 m/s.

 

Interface [Type 7 Contact]:

The graph was obtained for the Interface [Type 7 Contact].

The maximum force is 0.0164053 KN.

 

Intrusion Spring with Node 66695:

The graph was obtained for the Intrusion Spring with Node 66655.

The maximum intrusion value obtained for this node is 118.335 mm which is 11.8335 cm.

 

 

Intrusion Spring with Node 66244:

The graph was obtained for the Intrusion Spring with Node 66244.

The maximum intrusion value obtained for this node is 49.7764 mm which is 4.97764 cm.

 

 

 

 

Variation in Sectional Forces:

 

 

All Energies:

All the energies have been plotted.

 

Kinetic energy:

The kinetic energy decreases. Due to the decrease in velocity. Because the given velocity is the initial velocity, which may reduce.

Contact energy:

The contact energy will increase when the car hits the rigid wall. Because only some of the elements at the front will be having the contact.

 

Internal energy:

The internal energy will gradually increase. Due to an increase in displacement.

Total energy:

 

The total energy will be decreasing due to the decrease in kinetic energy.

Result:

Hence the COG from the initial position has been changed to the required position by mass balancing.

Hence the penetrations and intersections have been verified successfully.

Hence the interfaces were created newly.

Hence the accelerometers were created at the base of the B-pillar to obtain the acceleration.

Hence the initial velocity was assigned.

Hence the springs were created to obtain the intrusions.

Hence the rigid wall was created successfully.

Hence the TH for all inputs was created in order to obtain outputs.

Hence the simulation was run successfully without any errors.

At last, all the graphs were plotted with the obtained results.

 

Conclusion and Learning Outcome:

In this Challenge, I came to know about

How to change the COG position.

How to check for the penetrations and intersections.

How to create the interfaces and how to find connectivity, to check whether the free parts exist in the component.

How to create the accelerometers.

How to assign the initial velocity.

How to create the springs to obtain intrusions.

How to create a rigid wall.

How to request outputs.

Learned about the FMVSS [Federal Motor Vehicle Safety Standards] 208.

Learned about the sectional forces, and axial forces.

 

https://drive.google.com/drive/folders/13GBcpZhucTLI7HX_dmC8IjhSqMQ9WLqJ?usp=sharing