Side Pole Crash of car in Hypermesh RADIOSS.

Side Pole Crash of car in Hypermesh RADIOSS.

AIM: To conduct the simulation of side crash test of the given BIW of a car.

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

Output requests:

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

Note:

1. Submit your simulation files including time and h3d files.
2. Plot energies and notice any difference.
3. Explain your errors and how to rectify?

Image 1. BIW

INTRODUCTION

1. BIW(Body in White)

• Body-in-white is the name given to a car body's sheet when all its components have been welded together.
• BIW consists of barring moving parts (e.g., hoods, fenders, etc.), trims (e.g., glass, seats, etc.), or chassis sub assemblies.
• Image BIW shows the example of the BIW of a car.
• BiW constitutes about 27% of a car’s curb weight and remains the key determinant of how the car will perform.
• BiW can be made into two structures types.
• The more common monocoque structure where all body members are carrying load with chassis in-built with BiW and are integrated with each other.
• And the body-on-frame structure where the frame is the main load-carrying member.

Image BIW

2. CRASH TEST

• A crash test is a form of destructive test usually performed in order to ensure safe design standards in crashworthiness and crash compatibility for various modes of transportation.
• Crash tests are conducted under rigorous scientific and safety standards.
• The main aim of these crash tests is to collect the data o how the car is crashed in actual accidents and impact on driver and passenger.
• There are many companies which conducts these physical car crash test to collect those data.
• Each crash test is very expensive, as complete vehicle is crashed, so the maximum amount of data must be extracted from each test.
• Usually, this requires the use of high-speed data-acquisition, at least one triaxial accelerometer and a crash test dummy, but often includes more.
• There are many types of crash tests, most common types of crash tests are

1. Frontal Impact test

2. Side Impact test

3. Roof Strength test

• For this project the Frontal Crash test is conducted on the BIW of car model.
• This model consist only front and middle section of the complete BIW of that car due to the limitation of the number of elements in the model to run the simulation.
• The maximum limit of number of nodes for the Student version of the Hypermesh is 1,00,000 nodes.
• The complete car model has more than 3,00,000 nodes which is not supported in the Student version of Hypermesh.
• Hence the side crash is made on the BIW and all the components are recreated using rigid bodies so as to reduce the number nodes.

3. SIDE CRASH TEST

Image 3.1 Side Pole Crash Test

• Side Pillar car crash test is a type of Crash test by making the car to hit a Pillar side ways
• This test is conducted to determine

1. Distribution of impact force on the BIW structure

2. Intrusion of the dashboard into the driver's cabin

3. Adult Occupant protection.

4. Child Occupant protection.

• Side Pillar crash is conducted as there is much risks for the driver involved in the event os Side car crash.
• Also the crumble zone at the side is very less hence more risk of driver and passenger.
• There are two types of the side crash test

1. Side Barrier Test

2. Side Pole Test.

• In this project Simulation of Complete Side Pole Car Crash Rest is done on the given BIW of the car.
• For this project Only the distribution of forces and intrusion of the B-pillar, hinge pillar and fuel tank region are calculated as there is no dummies present in the model.

PROCEDURE

1. Checking the unit system

• To check the unit system the radioss file is opened in the notepad
• Below the begin card there will be the unit system
• In this model the unit system was kg mm ms (refer the image 1.1.1)

Image 1.1.1 Unit system in the model.

2. Checking for penetration

• Penetration is checked in the hypercrash as it is easier to find penetration in hypercrash than in hypermesh
• To check for penetration first model is imported in the hypercrash.
• To import the model drag the frontal_crash_0000.rad file from the file location and drop into the hypercrash window.
• To check for penetration Quality>Check All Solver Contact Interfaces.(refer the image 2.2)

Image 2.1 Model

Image 2.2 Check penetration

Image 2.3 No penetration

• In this model there was no penetrations.

3. Compare the model weight with the full scale 300k nodes model and use added masses to reach target weight 700kg while getting CG about the required range.

• To check for COG in the model Mass>Balancing
• A new will be opened below in that tab shows the total mass of the component and the location of the COG.
• Here the total mass of the component is shown in the tab.
• The total mass was found to be 188.42kg(refer the image 3.1)
• To check the COG location in the model click on the Show COG point icon(refer the image 3.2)

Image 3.1 Total mass of the car model before adding the mass.

Image 3.2 COG initially

• The COG of the component is to be shifted rear of the initial position and the total mass of the components should be 700kg
• Total mass is to be 700kg because in the simulation only part of the car is involved. So by adding some mass at certain places will recreate those situation for example adding the mass of driver and his seat at the location of the seat mount in the floor panel.
• In this case mass is added at certain places, below table shows the how much mass is added for certain reason and its location.

Mass in kg	Description	Location
70	Driver and his seat	Floor Panel Image 3.3
70	Passenger and his seat	Floor Panel Image 3.4
100	Fuel tank	Floor Panel Image 3.5
20	Dashboard	Floor Panel Image 3.2
274	Floor Panel and Auxiliaries	Seat Reinforcement Image 3.6

Image 3.2 20kg mass recreating the dashboard.

Image 1.3.3 70kg mass recreating the driver and his seat.

Image 3.4 70kg mass recreating the co-driver and his seat.

Image 3.5 100kg mass recreating the fuel tank.

Image 3.6 274kg mass recreating the Floor panel and Auxiliaries.

• By adding these masses the total mass of the model was 700.5kg(refer the image 3.7)
• And the Center of Gravity was shifted rearwards and was below the Seat Reinforcement.(refer the image 3.8)

Image 3.7 Total mass of the model.

Image 3.8 Center of Gravity of the model.

4. Initial velocity of the model 35Mph and creation of Pole.

• For this crash test initial velocity is given to the model to recreate the crashing scenario.
• In this simulation the initial velocity given to the model is 35Mph or 15.6464mm/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.(refer the image 4.1)

Image 4.1 Initial velocity

• After assigning the inital velocity a rigid pole is to be created.
• To create a rigid pole Model view>Create>Rigid wall>In the tab below change the geometry type as cylinder>set the diameter as 264mm>Set the co ordinate of the cylinder center>set the direction of the normal(y-direction)>Select the all the nodes in group node id.(refer the image 4.2)

Image 4.2 Creating the rigid wall.

5. Time Step: 0.5 to 0.1 micro sec

• For this simulation the time step given is should be in between 0.5 micro sec to 0.1 micro sec.
• The time step selected for this simulation is 0.1micro sec I.e 0.0001ms which is the unit given in the simulation.
• Time step can be set in both in HyperCrash and in Hypermesh.
• This process is done in Hypermesh.
• To import the model in the Hypermesh Import>Solver Deck>Select the starter rad file>Import.(refer the image 5.1)

Image 5.1 Importing the model.

• To set the time step value Engine card should be created I.e DT card.
• To create this DT card Solver view> Create>Engine Keywords>DT>DT.(refer the image 5.2)
• In the DT card set the value of Tmin(time step) to 0.0001ms and Tscale as 0.9 (default vaue).(refer the image 5.3)

Image 5.2 DT.

Image 5.3 DT card.

6. Run for 80ms.

• The run time for this simulation is 80ms I.e simulation of the frontal crash of the car is done for only 80ms.
• To set the value of the Run time to 80ms create ENG_RUN card.
• This card is created in the solver panel.
• To create ENG_RUN card Solver View>Create>Engine Keyword>Run.(refer the image 6.1)
• After creating the card set the value of Tstop to 80ms.(refer the image 6.2)

Image 6.1 ENG_RUN card

Image 6.2 Setting the value of Run time.

7. Output requests for the simulation.

7.1 Sectional force at the certain section of the car body.

• In the simulation section forces are calculated to check the distribution of forces of impact.
• The impact force is transferred from the bumper, which is the primary contact with the rigid wall, to the floor panel.
• To calculate the forces transferred through the components such as bumper to rails, through rails, through shotgun if the car and in A-Pillar a section is to be created on those components to view the forces.
• TO create a Section a frame of reference is needed, to create a frame Solver view>Create>FRAME>MOV> Now select the Origin Node, z axis and y-z plane node(refer the image 7.1.1).
• After creating the frame Solver View>Create>SECT>SECT> In the tab below Select the N1, N2 and N3 node for creating the skew> Select the frame>Select the group shell elements which are surrounding to the section>Set the value of Deltat and alpha as 0.1 and 0.67. (refer the Image 7.1.2)
• To check the section Model view>Cross Section>A-Pillar>Right click on A-pillar>Review>In the graphic area view the section if all the elements are inter connected.(refer the image 7.1.3)
• Similarly sections at other places are created.(refer the image 7.1.4)

Image 7.1.1 Creating the frame

Image 7.1.2 Creation of Section

Image 7.1.4 Review of the Section created.

Image 7.1.4 All sections created at different location on the model.

7.2 Intrusion on the Side wall

• During the side crash the passenger compartment tend to collapse as the pillar hits the door.
• So knowing the intrusion of the B-pillar, hinge pillar and at the rear end i.e near fuel tank would help in analyse the structural strength of the car.
• To create a spring 1-D>Springs>Select the two nodes one at the font end of the passenger cabin and one at cross member.(refer the image 7.3.1)
• After creating the spring elements a property is assigned to that spring(refer the image 7.3.2).
• To find the compression of the spring a time history file is created.
• To create the TH file Solver view>Create>TH>SPRING>In the tab below select the two elements.(refer the image 7.3.3)

Image 7.3.1 Creating the Spring.

Image 7.3.2 Assigning the Property

Image 7.3.3 Time history file for Spring Element.

8. Starting the Simulation of Frontal Crash of the given BIW

• Before running the file check for any errors in the model.
• To check the errors in the Hypermesh Tools>Model Checker>Radioss block(refer the image 8.1).
• Errors in the model is shown if there are any errors, also it will show the warnings.
• The solver will run the simulation if there are any warnings but will not if there are errors.
• To start the simulation Analysis>Radioss>Save as Name_0000.rad in a new folder>-nt 4 in the options for faster simulation>Radioss.(refer the image 8.3)

Image 8.1 Model Checker

Image 8.2 Model Checker after clearing the errors

Image 8.3 Radioss

• On clicking the Radioss a new solver Screen will open, in that Solver screen all the calculation processes are shown.
• After completion of the simulation results button is shown in the solver screen.
• If there are errors in the model the Simulation will not run i.e in Solver screen it is shown as SOLVER FAILED.
• In the output file all the errors are shown with its ID.

RESULTS:

• This simulation took hrs to run completely and ran with NORMAL TERMINATION.
• The energy error of the simulation was found to be % which is in the acceptable range.
• Also the mass error was found to be kg which is less than 1% of the total mass of the BIW.
• On clicking the Results button the animation of the simulation was shown in Hyperview.
• Animation 1.1 shows the animation of the Car BIW hitting the pole at 15.6464m/s speed.
• Using the Contour plot tool in the hyperview Vonmises stress induced in the BIW is shown.
• Animation 1.2 shows the Von Mises stress induced in the BIW during the test.

Animation 1.1 Simulation of the car BIW crashing side ways.

Animation 1.2 Von Mises Stress induced in the BIW.

GRAPHS:

1. GRAPH OF ENERGIES VS TIME GRAPH

• In the Hypergraph 2-D the graph of Energies vs Time is plotted.
• To plot the graph of the Energies vs Time Build Plots>Upload the Time history file>Select the X-Type to Time>Y-Type to Global variable>Y-Request- Contact Energy, Internal Energy, Kinetic Energy, Total energy and Hourglass energy>Y-Component MAG.(refer the image 1.1)
• Graph G.1 shows the graph of the Energies vs time.

Image 1.1 Build Plots.

Graph G.1 Energies Vs Time.

• In the graph the Total energy of the simulation is decreases gradually as the contact energy increases.
• The maximum Contact energy of the simulation is 1.825105e+03 J.
• As the the BIW hits the rigid wall the Kinetic energy of the BIW reduces as the velocity is reduced.
• This Kinetic energy is converted into deformation and hence the internal energy of the BIW is increasing.
• Since the simulation time only 80ms the velocity of the BIW does not reach zero.

Energies	Maximum Point	Minimum Point
Total Energy	8.561711e+04 J	8.330646e+04 J
Kinetic Energy	8.561711e+04 J	4.923527e+04 J
Internal Energy	3.407119e+04 J	0.000000e+00 J
Contact Energy	1.825105e+03 J	0.000000e+00 J
Hourglass Energy	0.000000e+00 J	0.000000e+00 J

2. SECTION FORCES IN CROSS MEMBERS

A. Section force in the Cross Member below the driver seat.

• To plot the graph of Section forces vs time graph Build Plots> Upload the Time history file>Select the X-Type to Time>Y-Type to Section Forces>Y-Request- Seat_reinforce_001>Y-Component Resultant Normal Force, Resultant Tangent Forces and Resultant Total Force.(Refer the image A.1)
• The graph G.A.1 shows the graph of Section forces vs time.

Image A.1 Build Plots

Graph G.A.1 Graph of Resultant forces vs Time.

• From the graph the Total Resultant forces increases suddenly as the car hits the pole.
• The maximum force transferred into this section was found to be 8.931569e+00 kN.
• There is drop after 30ms this is due to the deformation of cross member.
• And again the force increases after deformation of the cross member.

B. Section Forces in the Cross Member beside the B-Pillar.

• To plot the graph of Section forces vs time graph Build Plots> Upload the Time history file>Select the X-Type to Time>Y-Type to Section Forces>Y-Request- 2 rails_001 >Y-Component Resultant Normal Force, Resultant Tangent Forces and Resultant Total Force.
• The graph G.B.1 shows the graph of Section forces vs time.

Graph G.B.1 Graph of Resultant forces vs Time.

• From the graph the Total Resultant forces increases suddenly as the car hits the pole.
• The maximum force transferred into this section was found to be 1.733650e+01 kN.
• There is drop after 17 ms this is due to the deformation of cross member.
• And again the force increases after deformation of the cross member.

3. INTRUSION AT THE DASHBOARD

• To find the intrusion of the dashboard elongation of the spring of negligible mass and stiffness is determined.
• To plot the elongation of the spring Build Plots> Upload the Time history file>Select the X-Type to Time>Y-Type toSpring Elongation>Y-Request-110021>Y-Component Total elongation.(refer the image 3.1).

Image 3.1 Build Plots

Graph G.3.1 Elongation of the Spring

• From the Graph the elongation is in Negative direction this is due to the compression of spring as the side of the car is getting crushed.
• The intrusion at the B-Pillar was maximum as the B-Pillar was the Primary contact during the crash.
• The intrusion at B-Pillar was found to be 9.212064e+02 mm.
• The intrusion at Hinge Pillar was 4.052285e+02 mm and at fuel tank region was 8.200656e+02 mm.

CONCLUSION:

The Side Pole Crash Test of the given car BIW is Simulated in Hypermesh and required output requests are plotted and explained.

From the simulation Section forces at different location is shown using the Forces vs Time graph.

Also the intrusions at different section of the car was found using the spring of negligible mass and stiffness.