Assignment 8-Roof Crash Simulation Challenge

Assignment 8: - Roof Crash Simulation

Aim -

To run the roof crash simulation on the neon car model and plot the graphs for the neon car model in post-processing.

Objective -

To translate the impactor to the desired location as per the question.

To create a Type 7 contact interface between impactor and car.

To create a boundary condition for the suspension shock tower and lock them in the Z direction.

To create a moving SKEW to define the direction normal to the impactor.

To create an impactor boundary condition.

To apply an imposed displacement for the impactor.

To create control cards.

To set the termination time, nodal & element-time step.

To request the output and run the simulation.

To plot the graphs in the post-processing.

 

Procedure -

Phase 1-Check unit system and either follow [Mg mm s] or [Kg mm ms].

While opening hyper mesh software, A user profile window will pop up, Switch to the radioss user profile and start importing the model into the solver deck.

Now after switching the user profile to radioss, Import the model (starter file) into the radioss solver deck.

To import the model, Go to Standard Panel >> Import >> Import Solver Deck.

 

Import Solver Deck option should be selected to import the radioss starter file.

Import the model.

Next import the impactor.

 

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.

 

Phase 2-Transform the Impactor:

1. A 180° rotation about the global z-axis with the point opposite to C as the base point.

 

 

2. A 5° rotation about the axis through axis AB.

 

3. A 25° rotation about the axis through axis AC.

4. A translation to put point A at global ( -3500.00, 584.822, 1343.06).

Phase 3-Create the Interfaces:

1) Car and Impactor -

Here for this model, TYPE 7 Contact Interface is created with the recommended parameters. To create interface, Right Click on Solver Browser >> Create >> Inter >> TYPE 7.

First, we have to create Contact Interface for the Car and Impactor.

 

 

Select the slave and master nodes by switching to the components and select all the car components for slave for master nodes select all the components of Impactor.

 

 

 

2) Self Impact -

The Type 7 Contact Interface for the Self Impact is created.

 

 

 

Phase 4-Check for the Penetration

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

 

 

Phase 5-Create Boundary Conditions for the Suspension Shock Tower:

Here we have to create boundary conditions for the suspension shock tower.

To create boundary conditions,

Right Click on Solver Browser >> Create >> Boundary Conditions >> BCS

 

 

Go to 1D Panel >> Rigids >> Create >> In Nodes 2-n option, Switch to Multiple Nodes >> In Primary Nodes Option, Switch to the Calculate Node >> Create.

 

We need to deploy a cluster rigid connection on the suspension tower.

 

Phase 6-Create a BCS [Boundary Conditions] to Fix the Free End of the Spring:

Here we have to create the boundary condition to fix the free end of the spring. And rename it spring.

To create boundary conditions, Right Click on Solver Browser >> Create >> Boundary Conditions >> BCS

 

Now select the free end of the spring.

Now Constrain all the degrees of freedom for the free end of the spring.

 

 

Phase 7- Create a Moving SKEW to Define the Direction Normal to the Impactor’s Face:

Next, we have to create the boundary condition for the master node of the impactor.

For that first, we want the impactor to move only in the perpendicular direction to the impactor.

To give the boundary condition to the master node. we need to create a skew.

To create a skew, Right Click on Solver Browser >> Create >> SKEW >> Mov.

 

To create the skew, select the option to create by node reference and define the Z-axis and YZ-plane.

 

 

 

 

Phase 8- Create a BCS to Guide the Master Node of the Impactor Rigid Body:

Now we have to give the boundary condition to the master node of the impactor.

To give, we have to create a boundary condition and rename it as Impactor_Rigid_Master_Node.

To create BCS, Right Click on Solver Browser >> Create >> Boundary Conditions >> BCS,

 

 

 

Phase 9-Give the Imposed Displacement to the Impactor:

Here we have to give the imposed displacement to the impactor.

To give the imposed displacement to the impactor. We have to create the boundary condition.

To create the boundary condition, Right-click on the Solver Browser >> Boundary Condition >> IMDISP.

 

After creating the imposed displacement, we have to select the impactor master node.

To select the impactor node, Below the Parameter Window >> Right Click on gmd_ID >> Create Edit >> Entity ID >> Select the Node >> Proceed.

We have to create the curve to assign.

So, we want to impose the velocity of the impactor starting from 0 mm/s at t = 0 and the displacement of the impactor should

be 200 mm at 200 ms.

So, we have to create a curve. to create the curve, go to the Model Browser >> Create >> Curve.

 

 

 

Now Select the skew to move the impactor according to the skew.

Switch to the Z-Axis Direction to move the impactor in Z-Axis Direction

 

 

Reviewed the Impactor Master Node.

Phase 10-Create Missing Control Cards:

To create control cards, go to Analysis Panel >> Control Cards.

 

The time history file should be printed at 0.0001s. Create ENG_TFILE card

The simulation should be run for 200 ms. So create an ENG_RUN card

 

The animation file should be created for every 0.005s. So, create an ENG_ANIM_DT card.

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.

 

 

Values Entered in ENG_DT_BRICK, ENG_DT_INTER, ENG_DT_NODA Control Cards.

Next, we have to include elemental energy, equivalent plastic strain, hourglass energy, von mises stress. So, to include all these energies we have to create the ENG_ANIM_ELEM control card and check all these energies in the control card.

We have to request the TH to get the required output.

First request the TH for the Contact Interfaces, to create TH, Right Click on the Solver Browser >> TH >> INTER.

 

 

The Necessary control cards.

Phase 11-Checks:

Finally, after doing all the load case setup, we have to check for the errors, whether every load case setup is fine or not.

To check, Go to Tools >> Model Checker >> Radioss Block.

 

Next, the model checker window will be open.

There right-click on the browser and click run or hit on the green checkmark in the window.

 

 

Phase 12-Run the Simulation:

Now run the simulation, to run the simulation, go to Analysis Panel.

Go to Analysis Panel >> Radioss >> Select the Input File >> Save it in Different Folder and Rename it as Test-1 >> 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.

Here is the number of animation steps obtained.

 

 

Now go and open the 00001.out the file with notepad. First, we will check the Energy error and Mass error. So, we will open the engine .out file of the model and check the last row for Energy and Mass errors.

The obtained values for Energy Error, Mass Error, Internal Energy Error, and Kinetic Energy Error.

Here, the energy error obtained is -9.3%. The acceptable range for energy error is -15% to 5%.

 

Phase 13-Post Processing:

1) Review the Simulation using HyperView.

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.

Import the animation file .h3d into the HyperView.

 

Load the .h3d file.

 

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.

 

 

2) 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.

To plot the graph, Go to Hypergraph 2D >> Data File >>Roof_crasg_finalT01 >> Apply.

 

Interface [TYPE 7] Car and Impactor:

The graph obtained for the Type 7 - Total Resultant Force Interface (Car and Impactor).

Here the interface curve starts from the origin and reaches a peak due to collision.

And it goes on increasing due to the contact within the car.

 Interface [TYPE 7] Self Contact:

 

The graph obtained for the Type 7 - Total Resultant Force Interface (Self Impact).

Here the interface curve starts from the origin and reaches a peak due to collision.

FMVSS 216 Impactor Spring:

The graph was obtained for the impactor spring.

Kinetic energy:

The graph was obtained for kinetic energy.

Here in the above graph, we can see that In the starting the impactor will be moving, so it will be having some velocity.

So due to some velocity, there will be kinetic energy. When the impactor hits the car model the energy will transfer to the model and the kinetic energy of the model gets increases. So the kinetic energy goes on increasing.

Internal Energy:

The graph was obtained for internal energy.

 

 

The formula for Internal Energy is I.E = Q W.

Here the heat is neglected because there is no heat transfer, We will be having only work done.

W=FxD

F=ma

Here the internal energy is in Zero because there is no deformation initially, So the internal energy is in Zero and starts from Zero and goes on increasing.

The internal energy increases because the deformation is happening, there is a displacement, So the internal energy increases, when the displacement or deformation occurs.

Contact Energy:

The graph obtained for Contact Energy.

Here the contact energy starts from the origin, Cause the Car is in its initial condition.

Initially, there is no contact between the Car and the Impactor.

There is also no deformation initially, but when the Impactor goes and hits on the Car Roof, the contact energy starts increasing.

When the deformation or displacement happens to the car, the contact energy increases, causing the car component comes into the contact with the impactor. So, the contact energy goes on increasing.

Hourglass Energy:

The graph obtained for Hourglass Energy.

 

[Note: Hourglass Energy should be less than 5% of Internal Energy.]

Here the hourglass energy is less than 5% of internal energy, so it’s fine.

Total Energy:

The graph obtained for Total Energy.

 

Total Energy is the sum of Kinetic Energy + Contact Energy + Hourglass Energy + Internal Energy.

Here total energy starts from the origin, and it goes on increasing, why because the total energy is the sum of Kinetic Energy + Contact Energy + Hourglass Energy + Internal Energy.

Kinetic energy is directly proportional to the total energy.

So, the total energy goes on increasing.

All Energies:

All the energies have been plotted.

Force vs Displacement:

We have to plot the Force vs Displacement, to the plot, first, we have to plot the displacement graph.

To plot the displacement graph, Go to HyperView >> Build Plot.

Next in the drop-down list box, Choose the Result type as Displacement, and then select the Magnitude.

Next, we have to plot the total resultant graph.

We have to select the interface which we created for the car and impactor. it is named TYPE 7. select that interface.

 

To activate, Go to Menu Bar >> File >> Load >> Preference Files >> Vehicle Safety Tools.

To cross plot the Force and Displacement curve, go to the Math Option in Menu Bar >> Two Curves >> Cross Plot.

Next plot the cross plot for the Force and Displacement.

Use Current Plot while plotting the curve for Force and Displacement.

 

To rename X-Axis and Y-Axis to the Force and Displacement, Double Click on the X-Axis and Y-Axis, then rename it as Force and Displacement. 

The graph obtained for the Force vs Displacement

Check the FMVSS 216 target load of 47,000 N (= 3 * GVW) has been met:

To calculate the target load of the FMVSS 216, We should check the initial mass of the car, it is around 174.8487 kg.

To convert it into the weight, we should consider the gravitational force.

Load=3xGVW.

Load=3x9.981x174.848.

Load=3x1715.2657.

Load=1,715.2657N.

The target load given is 47000 N but the load attained here is 10% (1715.2657) of the target load.

This is due to, cause the car model given to us is not a complete car, it’s a BIW body, so the target load we attained here is 1715.2567 N.

For the whole car, the mass will be 1600 kg, if we check with this, we will be getting the target load as =3x9.91x1600=47088 N.

If we run the simulation with the complete car, we will be getting the exact target load and it will meet the target load. but here the target load is not met.

Result:

Hence the Impactor has been positioned according to the given axis.

Hence the two interfaces created for the self-impact, car, and impactor.

Hence the Boundary Condition created and locked the two nodes of the Z-Axis for the suspension tower.

Hence the Boundary Condition was created to fix the free end of the spring.

Hence the SKEW was created to define the direction normal to the impactor’s face.

Hence the Boundary Condition was created to guide the master node of the impactor's rigid body.

Hence the Imposed Displacement is given to the Impactor.

Hence all the necessary control cards were created.

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 Learned about

Learned about the roof crash test.

Learned to create boundary conditions.

Learned to translate the impactor according to the given axis.

Learned to create imposed displacement.

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

Learned to create cross plots.

Learned to request outputs.

Learned about the FMVSS [Federal Motor Vehicle Safety Standards] 216