Assignment 7-Side Pole Crash Simulation Challenge

Aim:-

• To perform a side pole crash simulation with the given BIW frame in Radios and request for outputs as mentioned in the problem
  statement.

Neon side crash -BIW:-

• Check the unit system and either follow [Mg mm s] or [Kg mm ms].
• Create an appropriate interface, friction 0.2, and recommended parameters.
• Make sure of no penetration and intersections.
• Create a rigid wall with friction 0.1 as per the reference model.
• Compare the model weight with the reference model and use added masses to reach the target weight of 700kg while getting CG about the required range.
• Initial velocity - 20mph, as per the standards.
• Use a model checker to ensure good quality.
• Timestep :0.5 to 0.1 microseconds.
• Run 80ms.

Output requests:

• Sectional force in the cross member.
• The intrusion at the B pillar, hinge pillar, and fuel tank region. Provide recommendations on what can help to reduce Fuel tank intrusion.
• Peak velocity of an inner node of the door.

Step 1:- Intersection and penetration checking

• Before opening the model check units for further results from the starter input file.
• Import the given model "neon_side_reduced_0000" into Hypermesh GUI.
• To check for penetrations in the model, we will go to the Tools menu on the Menu bar and click on the Penetration Check option.
• The penetration check panel will select all the components and click on the Check command. The software will check for
  penetrations and then display the results as shown below,
• 
• There are no penetration or intersection errors found.

Step 2: - Balancing COG

• The BIW model doesn't consist of the exact weight of the vehicle so Additional mass should be added to the BIW model
  considering the weight of the Body after manufactures e.g. with the weight of the seats, the weight of the persons, and all other
  weights in realistic conditions.
• The targeted weight is given 700kg where the actual mass before adding external weight is 166kg.
• To Add the mass, Click on added mass, and to create a new object Select - Mass is distributed to each node of the node
  group, and click save
• 
• Check COG, simultaneously after giving the mass in the balancing menu.
• Add mass according to the needs till the point reaches the center and till the mass attains the target value. Below, the image shows
  that COG is present in the required location i.e. under the driver's seat.

Step 3: - Creating contact surfaces.

• A contact interface should be defined to view the contact energy. Here the type-7 Contact is used (Node to Surface), because
  of its high accuracy and correct physical representation. The self-impact is defined in the Contact interface as the body acts as
  both master and Slave.
• Interface properties Changed to recommended conditions as per mentioned in the problem statement
• 

Step 4: - Rigid wall

• To create a cylindrical rigid wall on the left side of the car, we will need the outermost node at the front left door of the car. So we will
  create the outermost node on the element edge using the temp nodes option.
• Then we will right-click in the solver browser and navigate to Create > RWALL > CYL. In the RWALL panel, under Engineering data.
• we will specify the coordinates of the pole which will be at some.
• Distance from the outermost node on the side door. Then we will give the normal direction to the pole on the Z-axis and the diameter of the pole to be 254 mm.
• The FRIC value will be 0.1 and Dsearch value will be 1000 as shown below.
• 

Step 5:- Initial velocity

• In this simulation, the initial velocity given to the model is 20Mph or8.94mm/ms.
• To set the initial velocity of the model LoadCase>Initial Velocity>Set the value of the velocity in Y-Direction>Select all nodes>Yes>Save
• 

Step 6:- Section creation

• The results which we want on required cross-sectional parts will be calculated based on a frame of reference. So before
  creating a cross-section, we will create moving frames on a particular node of that section.
• Now as we have to create the moving frames which are also called as local axis, we have to perfectly align our local axis to the global axis.
• Now we can create a moving frame using these nodes. In the Solver browser, we will right-click and navigate to Create > FRAME >MOV. So here, we will create frame by node reference and select the nodes for the x-axis and XY plane and then click on create.
• Thus a moving frame will be created. Now we will create a cross-section for this frame. To create a cross-section, we will right-click on the Solver browser and navigate to Create > SECT.
• In the section panel, we will specify the Frame_ID as the moving frame which we created and the delta value as 0.1. From the Hyperworks help menu, we get that the general value of alpha is taken as Thus we will specify alpha as 0.6.
• We will right-click and create grshel_id, then we will select the elements where we want the cross-sectional results. Thus the cross-section will be created as follows.
• 

Step 7:- Run model checker to ensure good quality

• To check the quality of the model in Hypermesh, in Menu Bar we will navigate to Tools > Model Checker > RadiossBlock. This will open a
  new Model Checker browser.
• In this browser, we will click on the Run checks command which is at the top right side in the above figure, indicated in the red box.
• 
• After running the checks, we get zero errors only warnings are shown we can ignore these warnings and move further. From the above figure, we can ensure that the quality of the model is good for simulation.

Step 8:- Set time step and runtime

• To check these parameters in Hypermesh, we will navigate to Cards under the Model browser.
• To check the run time, we will open the ENG_RUN card where we will see that the model already has the run time in Tstop as 80 ms.
• For the time step, we will open the ENG_DT_NODA card and we will change the Tmin value to 0.0005 ms.
• 

Step 9:- Output request

• Peak velocity of an inner node of the door.
  To find peak velocity at the inner node of the door, we will create a moving frame at the node location by using the same procedure
  as we used in cross-section creation. Then we will create an output block for the peak velocity by specifying the node and the frame or
  skew based on which the peak velocity is calculated as shown below.
• 
• Intrusions at B-pillar, hinge pillar, and fuel tank:-
  Here, we need to find the intrusions at B-pillar, hinge pillar, and fuel tank. So to find the results in the specified parts, we need to have a
  frame of reference. Thus we will create moving frames on the opposite side which are at the right B-pillar, the hinge pillar right side, and the fuel tank opposite side as shown below.
• 
• Sectional forces in cross members
  For this, we will go to Output Blocks under the Model browser. Then we will right-click and create a new output block. Under Entity
  IDs option, we will select the cross-section which we created and thus we will be able to plot graphs of the cross-sectional forces in Hypergraph.
• 

RUNNING THE ANALYSIS IN RADIOS

• Switching to Hypermesh, moving to Analysis > radios, we can click 'save as to save the file if it hasn't been saved yet. Care must be
  taken to include '_0000.rad' in the file name since it's the starter file.
• After that, we can check the connectors option and input '-nt 4' in the options bar before clicking 'Radios'. This starts the Radios simulation.
• 

ANALYSING THE OUTPUT FILE

• The next step is to carry out energy error and mass error checks and this is done by analyzing the RADIOSS engine output file. This can
  be accessed from the same directory as the starter and engine files and is denoted by the '.out' extension. The file in question
  contains '_0001.out' and can be accessed using any text editor - such as Notepad.
• 
• As we can see, the energy error is -1.5%. It is definitely acceptable due to its proximity to a 0.529% error. In addition to that, the mass error is 0.529%, there is a mass error.

SIMULATION ANIMATION

• To view the simulation, we can switch to Hyperview through the client selector.
• 
• In Hyperview, we will need to import the h3d variant of the file. After importing, we can then select the 'contour' tool to switch to the
  Von Mises contour so we can analyze the stresses that form within the BIW in the simulation. This is what the simulation looks like:

Von Mises stress contour plot

Generate Output Plots

• After generating the simulation, we can then go ahead and generate the plots. Using the same client selector, we can switch to
  Hypergraph. In the Hypergraph client, we need to import the time history file T01 file.
• 
• On importing, we can build the plots using different variables. We shall first look at general plots of energies and rigid wall forces
  generated in and by the entire BIW respectively.
  

Global Variable - Energies

• The changes in kinetic and internal energies occur at the exact moment the BIW makes contact with the rigid cylindrical wall.
  Understandably, the BIW loses kinetic energy throughout the simulation due to the obvious decrease in velocity.
• At the same time, it absorbs the forces, and this results in an increase in internal energies, and as a result, the deformations also occur.
• 

Rigid Wall force:-

• 

Sectional force in the cross member:-

• 

Peak velocity at the inner door:-

• 

Intrusion inside the car at hinge pillar:-

• 

Conclusion:-

• Side crash analysis was carried out on the given BIW model of the Dodge Neon as per requirements.
• The output requests were also generated after the creation of cross-sections in each of those regions. Peak velocity and intrusion values were also measured at certain points of the model.
• Fuel tank intrusion and intrusions, in general, could be reduced by using anti-intrusion beams (or side-impact beams) between the
  pillars. They increase the rigidity of the doors and distribute the energy in the event of a side-on crash.