Assignment 7-Side Pole Crash Simulation Challenge

Project 2: Side pole crash simulation with given BIW frame in RADIOSS

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.

Software used:- Altair hyper-works student version 2020 and Hyper-Crash 2020

Problem statement:-

Neon side crash -BIW

• Check 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 is shown in the picture
• Use a model checker to ensure good quality.
• Timestep :0.5 to 0.1 microseconds.
• Run 80ms.

• Output requests:

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

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 to ensure safe design standards.

Frontal crash Test

SIDE CRASH TEST:

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.

BIW (BODY IN WHITE)

Body in white (BIW) is the stage in Automobile Manufacturing in which a car body's frame has been joined together, that is before painting and before the motor, chassis sub-assemblies, or trim (glass, door locks/handles, seats, upholstery, electronics, etc.) have been integrated into the structure. Assembly involves different techniques such as Welding (spot, MIG/MAG), Riveting.

Solution:-

Step 1:- Intersection and penetration checking:-

Before opening the model check units for further results from the starter input file.

There is no penetration or intersection error 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 condition.
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 Type0 - 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 on the required location i.e. under the driver 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 mentioned in the problem statement and create another interface for bumper and rail contacts. which is shown in the image below.

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 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 in the Z-axis and the diameter of the pole to be 254 mm. The FRIC value will be 0.1 and the Research value will be 1000 as shown below.

Step 5:- Initial velocity:-

In this simulation, the initial velocity given to the model is 35Mph or 15.6464 mm/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. :-

1. 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 the local axis, we have to perfectly align our local axis to the global axis.
2. 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.
3. 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 > 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.

. Thus we will specify alpha as 0.628. 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:- 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 0.5 ms.

RUN THE SIMULATION:

• Click on the analysis panel in the Hyper mesh.
• Save the model in the local directory.
• Type -at 4 in option and click on Radios.

Simulation in Hyperview:

Animation of the crash simulation is as follows:

In the above crash simulation of the vehicle, we can see the vehicle's 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 the 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. the stress is more in B-pillar and crosses 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 analyzed.

INTERNAL ENERGY:

CONTACT ENERGY:

TOTAL ENERGY OF THE SYSTEM:

From the above plot, we can see that there is a 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*mm2/ms2 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.

TOTAL RESULTANT FORCE:

Peak velocity of an inner node of door:-

This plot helps to understand, 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 comes in the contact with the force during the side crash.