Side crash analysis on Dodge neon car BIW using FMVSS 214 standards

Objective

Perform the side crash simulation on the neon car model.

In this project, we are going to make sure that there is no penetration and intersection in the model. Create the rigid wall with the friction of 0.1. We have to add the mass in the car to make the total mass of the car to be 700 kg. We have to create sections and check the sectional forces there. We have to check the intrusion in the given part of the body. We have to check the peak velocity at the inner node of the door.

Introduction

BIW

Body-in-white (BiW) is the name given to a car body’s sheet when all its components—barring moving parts (e.g., hoods, fenders, etc.), trims (e.g., glass, seats, etc.), or chassis subassemblies—have been welded together. Usually, BiW constitutes about 27% of a car’s curb weight and remains the key determinant of how the car will perform.

Side Crash

The objective of a crash test is to measure how well a passenger vehicle would protect its occupants in the event of a serious real-world side crash. Federal Motor Vehicle Safety Standard (FMVSS) No. 214 is the measure that gives us the valuers that how much it can be deformed so the passenger should not get injured that much. If it is within the limit then we can say that the car has passed the test otherwise it is failing.

Side crash tests are performed to simulate crashes that usually take place in intersections. These tests are done usually by using two cars or a car has been hit on a solid obstacle.

Car to Car Side Impact Test – The vehicle is hit on the driver’s side by a mobile deformable barrier traveling at 54 km/h (35 mph). An important part of the test is evaluating how the car side intrudes and almost all cars going through this test are equipped with side airbags.

Pole Side Impact Test – The test involves a vehicle being projected sideways into a rigid pole at 32 km/h (18 mph). The pole’s diameter is 254 mm (10 inches) and it seriously damages the car.

In the side pole impact collision cases, When the car gets crashes to the pole the load goes transferred to the car. So because of the load, it starts to deform and its contact with the dummy pelvis location. Pelvis position and orientation are important aspects of a vehicle occupant’s posture. Measurements of drivers’ or passengers’ pelvis locations are used for ergonomic or crash safety studies such as the development of posture prediction models, analysis of lap belt fit, and development of computational human models. Due to this structure to pelvis contact, the load has transferred to the occupant. As only a very small crumble zone is available during a side pole impact, so we have to ensure that the impact forces are distributed over a wide area. The B-Pillars and side members along the flanks of the vehicle are mainly responsible for this. The impact forces are transferred from B Pillar to the opposite side of the vehicle first and foremost via the transversely rigid seat and the center console. A further load dissipation path runs from the base of the B pillar to cross member under the seat and transmission tunnel braces. Asper baseline study, identified the important load transfer path members are B-Pillar and its reinforcements, Roof bows, Sill, Transfers cross members. These parts stiffness increased by the way of design changes and material grade up.

In this test, we are going to give the velocity to be 54 km/h and we are going to take the diameter of the pole to be 254 mm as the standard diameter value according to the FMVSS 214.

Procedure

1. We are going to choose the profile to be Radioss.

2. Now we are going to import the model.

3. Now we are going to check the unit of the model. For that, we will go to the BEGIN_CARD.

So the unit of the system is in kg, mm, ms.

4. Now we will go to the HyperCrash. To go there Application--> HyperCrash

We have to make sure that the unit system of the HyperCrash is in the [ kN, kg, mm, ms].

Now in the HperCrash to import the model we are just going to drag and drop the 0000.rad file. That will do the work.

5. Now we are going to check if there are any penetration and intersection in the model. For that we will go to the Quality--> Check All Solver Contact interfaces

Penetration

After click on the option HyperCrash check for the penetration and intersection and show us the result.

6. Now we are going to check the mass of the model. In order to that, we will go to the mass--> Balancing

So after selecting the balancing option we can see the mass of the model.

It is showing that the total mass of the body is 159.74 kg which is 700-159.74 = 540.26 kg less than our target mass.

To check the COG of the body we have to click on the specs icon.

7. We need to increase the mass of the body to be 540.26 kg and get the CG of the body to be in the required range we have to add the mass very carefully.

To add the mass we will go to the LoadCase--> Added Mass.

8. Now to add the mass we are going to click on the create on the new object in that we are going to add the mass and the nodes where we are going to add the mass.

We have to be very careful in adding the mass so that the CG of the model should be on the required area and we got the target mass of 700 kg of the model.

After adding the mass:-

And CG of the model:-

Now we have achieved the target mass of the car and we have got the COG in the required area.

9. Now we are going to export the model so that we can do the rest of the work in the HyperMesh. To export the model we will go to the File--> Export--> RADIOSS

Now we are going to save the file in the "0000.rad" format. And we are going to open that file into the Hypermesh.

10. Now in Hypermesh we are going to give the model a type 7 self contact. To create the contact we will go to the solver and we are going to create it.

In the contact, we are going to give the master and slave nodes. It is a self contact so we are going to take the master and slave nodes to be all nodes of the car model.

We are going to give the recommended value to the interface.

We are going to take the friction to be 0.2 because it is given in the problem so instead of the recommended value we are going to give friction to be 0.2.

11. Now we are going to create a rigid wall.

In the rigid wall creation, we have to give the coordinate of a base point of the surface where we want to create the rigid wall and we have to give the normal vector coordinate.

We have to give the friction of the wall to be 0.1. We are going to give Dsearch value to be 1000. Dsearch value is the value that gives us the search tolerance of the master and slave nodes near the wall.

12. Now we are going to give the initial velocity to the car. So to give the initial velocity we will go the create--> Boundary Condition --> Inivel

In the initial velocity first, we are going to select the node where we want to give the initial velocity. We want the whole body to move so we are going to select all the nodes of the car model.

We want the body to move in the x-direction so we are going to give the velocity in the x-direction only. We need to give the velocity to be 35 mph which we have to convert into the mm/ms. So after converting the velocity we got is 15.6464 mm/ms.

13. Now we want to calculate the sectional force in the cross member.

So we have to create the sections on these cross member. In order to create sections, we are going to need frames. So first we are going to create the moving frames in these points. In order to create the frame we will go the create--> Frame--> Mov

And we are going to create the frame on the required points. In the creation of the frames, we are gonna required the origin node then we are going to define the x-axis after that we are going to define the XY plane.

So the frames:-

14. Now we are going to create the sections so that we can check the forces on these points. So to create the section we will go to the Create--> Sect--> Sect

So while creating the section we have to select the frame and we have to select the elements which is near to the frame.

We are going to give the alpha value to be 0.67 and the delta T value to be 0.001.

So we have created the required section in the model.

15. We want to check the peak velocity at the inner node of the door. So we are going to create the node in the door.

So to calculate the peak velocity at the node we have to create the TH file for that node. In that, we are just going to select the node in the node entity.

16. Now we need to create the Intrusion on the B pillar, hinge pillar, and fuel tank region. So instead of that, we are going to create the spring on those areas.

So to create the spring we will go the 1D--> Spring

In that, we are going to create the spring between two nodes.

We have to give some property to these springs. In the property of the springs, we are going to give the mass of 0.001 kg and stiffness of 0.001 N/mm.

Now we have to assign the property to both springs.

17. Now we are going to check the connectivity of the model. We don't want any component of the model to be free. Because if there is any free component that remains on the model after the crash they will go fly away. That is bad for our simulation. We want the components to be connected for better results.

So to give the connection we will go to the 1D--> rigids

After we select two or more nodes, those two components will be connected by an RBE2 (Rigid Body Element) that will hold those components in place. An RBE2 element has infinite stiffness, it will not deform under excessive loads.

18. We need to give the time step value in brick to be 0.0001 ms.

In inter to be 0.0005 ms.

And in the Noda to be 0.0005 ms.

We want the simulation to be run for the 80 ms. So we are going to give the Tstop time to be 80.

We are going to give the Tfreq to be 5.

19. Now we are going to create TH file to get the required output.

So to create time history file we will go to create--> TH

So we are going to create all the required TH file.

So we have created the TH file for all the required outputs.

20. Now we are going to run the simulation. To run the simulation we will go to the Analysis-->Radioss

Now we are going to analyze the simulation and we are going to plot the required graph.

21. To check the simulation we have done is correct or not we are going to check the energy error and mass error. If it is in the accepted range then we can say that our simulation is correct.

The energy error is between -15% to 5% and the mass error is 0. That is very less so we can see that the simulation we have done is right.

The total running time of the simulation was 7438.31 seconds.

22. Now we have to analyze the simulation frame by frame and check the behavior of the element after the impact.

Output

Simulation Gif

We can see from the simulation we can see that the B-pillar of the model is crashing on the pole. So the elements of the B-pillar first start to deform. After that, the elements near the B pillar also getting deformed and with time all the elements are getting deformed. But the deformation is more in the B-pillar.

Displacement Gif

In this Gif, we can see that how many elements how much getting displaced. We can see that elements that are at the B-pillar are getting very less displaced because the crash is happening near that area so they are not able to move that much because of the pole. The elements which are in the front are getting more displaced.

Von Mises Gif

Von Mises stress is a value used to determine if a given material will yield or fracture. It is mostly used for ductile materials, such as metals. The von Mises yield criterion states that if the von Mises stress of a material under load is equal or greater than the yield limit of the same material under simple tension then the material will yield.

Energies

From the above graph, we can see that with the time, when the model gets impact on the wall the velocity of the model decreases, and because of that the kinetic energy also decreases. The internal energy of the model gets increases with time.

The total energy is the sum of the kinetic energy and the internal energy. So because of some contact energy, the total energy is decreasing at the end of the simulation.

Contact Energy is the energy due to contact between two elements. So when the deformation occurs elements start to get in contact with each other so due to contact between elements we get the contact energy. We are getting very low contact energy in the simulation.

We have taken the shell element to be QEPH so we get hourglass energy to be zero.

Sectional Forces

To check the forces on some particular area we have created sections. We have created sections at the cross members of the model. So in the above graph, we can see that how much of the forces are getting in those sections.

We can see that in the beginning, the section forces were zero because at that time the model was moving and the crash has not happened at that time. so it starts to increase when the crashing started. We can see that the forces are more in the rear section as compare to the front section.

Forces were decreasing with the time in the front section after 35 ms but the forces were increasing in the rear section after some time it decreases and at 58 ms it goes to the peak and after that, it decreases.

Node Velocity

This graph is showing the velocity of the node which is at the door. So we can see that the velocity is constant until it was moving freely. When the model gets impact on the pole it decreases very low and it increases and goes to more than the inlet velocity. We can see in the graph that the peak velocity we are getting on the node is 15.79 mm/ms.

The increase in the velocity is because of the law of inertia. When the model crash on the pole, it tries to satisfy the law of inertia, so the velocity of the model increases for a moment.

After an increase in the velocity, it decreases gradually and after 38 ms it increases very less and it becomes constant.

Intrusions

To check that how much of the deflection is happening in a particular node, we create the intrusion there. There are two methods to create the intrusion. The first is by creating skew at a point and the second one is by creating a spring at that node.

When we create moving skew it moves with the node when there is deflection. So when the skew moves, the origin of the skew does not change. The origin of the skew is fixed. So we can check the coordinate of the skew and we can know how much of the deflection is happened at that point.

When we create the spring at a particular node. In that case, we can check how much of the length changes of the spring. So we get to know that how much of the intrusion is occurring at that point.

We are going to create three springs at the B pillar, hinge pillar, and fuel tank region of the model to check the intrusion.

Hinge Pillar

In the above graph, we can see that in the beginning, the length of the spring was 1307.652 mm and after the crashing the length of the spring get 1415.931 mm. So the total deflection of the spring is 108.279 mm.

B Pillar

In the above graph, we can see that in the beginning, the length of the spring was 1323.810 mm and after the crashing the length of the spring get 624.286 mm. So the total deflection of the spring is 699.524 mm.

Fuel Tank

In the above graph, we can see that in the beginning, the length of the spring was 1312.03 mm and after the crashing the length of the spring get 402.396 mm. So the total deflection of the spring is 909.624 mm.

We can see that we are getting so much of the intrusion. It is 909 mm in the fuel tank region. That is a very large quantity of deformation. So we can say that the car is failing in the side crash test.

Learning Outcome

Learn about the side crash test and different types of side crash tests.

Learn about the FMVSS 214.

Learn how to add mass in the model and learn about the CG of the model.

Learn about the sectional forces.

Learn about the intrusions.

Learn about internal energy, kinetic energy, hourglass energy.