Assignment 7-Side Pole Crash Simulation Challenge

Neon side crash -BIW

• 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.

Aim :- To perform a side pole crash simulation with the given BIW frame in Radioss and request for outputs as mentioned in problem statement.
Software used :- Altair hyper-works student version 2020 and Hyper-Crash 2020

Introduction :-

In this project, I am working on a Side Crash using the BIW structure. The Side Crash Analysis is important for the occupant as well as passenger safety. If the holding structure is not good, all the impact force may travel into the main compartment and this leads to injured the occupant. Crash analysis is an integral part of safety analysis and is often completed at intersections and corridors. The crash analysis can help assess concerns and help
determine potential improvement options. A Crash test is a form of destructive testing usually performed in order to ensure safe design standards.

New Car Assessment Program (NCAP):
It is a government car safety program tasked with evaluating new automobile designs for performance against various safety threats.

Standard crash tests performed by NCAP:

1: Frontal offset testing (64 km/h proposed)
2.Side-impact testing
3.Pedestrian protection testing
4.Rear impact testing
5.Child dummy dynamic crash testing

FMVSS ( Federal Motor Vehicle safety standards):
Federal Motor Vehicle Safety Standards (FMVSS) are US federal Vehicle Regulations specifying design, construction, performance, and durability requirements
for motor vehicles and regulated Automobile safety-related components, systems, and design features. They are the U.S. counterpart to the UN Regulations
developed by the World Forum For Harmonization of Vehicle Regulations and recognized to a varying degree by most countries except the United States.

Solution :-

Step 1 :- Intersection and penetration checking :-

1. Before opening model check units for further results from starter input file.
2. Import the given model "neon_side_reduced_0000" into Hypercrash GUI.

Step 2: - Balancing COG: -

1. 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 condition.
2. The targeted weight is given 700kg where the actual mass before adding external weight is 18kg.
3. To Add the mass, Click on added mass, and to create a new object Select Type0 - Mass is distributed to each node of the node group, and click save
4. Check COG, simultaneously after giving the mass in the balancing menu.

5. Add mass according to the needs till the point reaches the centre and till the mass attains the target value. Below, image show that COG is present on
required location i.e. under the driver seat.

Step 3: - Creating contact surfaces.
1. 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.
2. Interface properties Changed to recommended conditions as per mentioned in problem statement and create another interface for bumper and rail contacts. which is shown in image below.

Step 4 :- INVEL

1. In this simulation the initial velocity given to the model is 35Mph or 15.6464 mm/ms.
2. 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 4 : - Rigid wall


To create a cylindrical rigid wall at 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 temp nodes option. Then we will right click in 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 side door. Then we will give
the normal direction to the pole in Z-axis and 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 6 :-

Section creation. :-
1. The results which we want on required cross sectional parts will be calculated based on a frame of reference. So before creating 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.

2. Now we can create moving frame using these nodes. In 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 x-axis and xy plane and then click on create.

3. Thus a moving frame will be created. Now we will create cross section for this frame. To create a cross section, we will right click on the Solver browser
and navigate to Create > SECT > SECT. In section panel, we will specify the Frame_ID as the moving frame which we created and delta value as 0.1.

alpha as 0.623.

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 at the specified parts, we need to have a frame of reference. Thus
we will create moving frames at the opposite side which are at right B-pillar, hinge pillar right side and fuel tank opposite side as shown below.

Peak velocity of 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 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

RWall:

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 Run checks command which is at the top right side in the above figure, indicated in red box. After running the checks, we get zero errors only warning are shown we can ignore these warnings and move further. From above figure, we can ensure that the quality of the model is good for simulation.

Output Requests :-

INTER
i. Self-Impact

SPRING
i. Intrusion on the Fuel tank
ii. Intrusion on the B-Pillar
iii. Intrusion on the Hinge pillar

RWALL

i. Rigid Wall

SECTION

i. Driver Rail
ii. B-Pillar Rail

NODE

i. Peak velocity node on (NODE ID 337773

RUN THE SIMULATION:
Switching to Hypermesh, moving to Analysis > radioss, 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 'Radioss'.

This starts the Radioss simulation

Simulation in Hyperview:
Animation of the crash simulation is as follows:

Displacement contour plot :-

In the above crash simulation of the vehicle, we can see the vehicle body is impacting on a Pole. After the impact, the frame of the vehicle deforms and the
vehicle body gets contracted around the pole with left B-Pillar as the pivot point. The CG of the vehicle is in the same axis or direction of the pole, so we can see
even deformation of the frame around the pole.

Von mises stress :-

The stress is more in B-pillar and cross members as B-pillar takes the initial impact and then the impact is transferred to the cross members.

Plots in Hyperview 2D :

The plots like energy differences, displacements, velocity and the normal forces are analysed.
TOTAL ENERGY OF THE SYSTEM:

From the above plot, we can see that there is high amount of Kinetic energy at the start of the simulation but as the simulation progresses, the kinetic energy in
the vehicle decreases and gets converted into internal energy, so the internal energy increases in the same proportion. Thus the total energy in the system is
almost constant at 85000 kg*mm /ms and due to some energy loss which we can see in energy error, there is some decrease in total energy. We can also see
some amount of contact energy in the model as we have defined the value of friction in Type 7 interface due to which contact energy is generated.

Sectional forces acting in cross members :-

From the above plot, we can see that the total resultant force in the rear cross member is more than the cross-member A. As the cross-member B is in line with
the Pole, it experiences more force.

Intrusions :-

Red line- Intrusion node at B-pillar
Green line- Intrusion node at fuel tank.

Peak velocity of inner node of door :-

This plot helps to understand, with how much the actual inner side of the door moves in the direction of the Driver during the pole impact. The peak Velocity measure at the inner door point is 15.84mm/ms till 8 ms. after that, the speed is starting to reduce to a great extent.

CONCLUSION :
Thus, the model was simulated for a side pole crash test and the results were discussed. From the output file the energy error and mass error is in an acceptable range. so, I can conclude that the simulation is pretty stable. Cross-members. A and B are playing important role in the Impact force absorption. So, improving the cross-member material or adding some extra support element near the cross member can improve their performance, also for the Fuel tank side as we discuss earlier need some reinforcement. We can also work on the B-pillar property improvement as it's the closest part which is comes in the contact with the force during the side crash.