Assignment 7-Side Pole Crash Simulation Challenge

                                                                             Side Pole Crash Simulation

Aim:

To run a simulation for the neon slide pple crash and to obtain the results in the post processing.

Objective:

• To check the unit system in the solver.
• To create an appropriate interface with friction 0.2 and recommended parameters.
• To check for the penetrations and intersections in the component.
• To create cylindrical rigid wall with a friction 0.1.
• To add extra mass to attain a target mass of 700 kg.
• To apply initial velocity to the car.
• Keep the min time step of 0.1 micron sec and max of 0.5 micro sec.
• Run the model up to 80 milliseconds.
• To find the sectional force in the cross member.
• To calculate the intrusions at the b-pillar,hinge pillar and fuel tank region.
• To calculate the peak velocity of an inner node of the door.
• To request TH for all the inputs created.
• To run the simulation.
• To plot the graphs in the post processing.

Output requests:

• Sectional force in the cross member.
• Intrusion at 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.

PROCEDURE:

Check for Unit System:

• Open the neon_side_reduced_0000.rad file in notepad.check the units are follows  kg, mm, ms.

• Important operation will be performed in HyperCrash, it will be opened by following (Application >> HyperCrash).

• The starting frame of HyperCrash will be displayed with units (kN mm ms kg) taken in reference as per the units (kg mm ms) in the starter file neon_side_reduced_0000.rad and finally select the Run option to open the HyperCrash.

Import File in HyperCrash:

• Select starter file neon_side_reduced_0000.rad and transfer it in the HyperCrash Window Frame to open the car model.

Penetration and Intersection:

• Penetration and Intersection operation will be performed by following (Quality >> Check All Solver Contact Interfaces). Contour window will open in which (include picked parts) option selected by following inside the fixed parts windows and finally click on the penetration option.

• After performing operation, it indicates that zero evidence of intersection and penetration is present inside the model.

Compare model weight with fully fledged 300k model and use added masses to reach the target of 700kg weight while reaching Centre of Gravity to the required location

• The centre of gravity for vehicle is a theoretical point at which all masses of each of its different individual components lies at one point.
• Sunroof at the top of the vehicle will raise centre of gravity of the vehicle while center of gravity will lower by placing battery pack at the bottom of the vehicle.
• Lower the centre of gravity better will be the handling point of vehicle during cornering and braking and also it reduces roll on. 

Added Masses:

• Addition of mass is essential in order to stabilize the centre of gravity of the car. The present model for crash simulation does not have many important components because of node limitation.
• The checking of centre of gravity of car will be done by following (Mass >> Balancing) process. In mass window frame, click on the (Show COG point) to check where the centre of gravity available at the moment in the model.
• In Mass overview, computed mass is 166 kg but it is required to add mass to compensate components which are not available inside the car model to reach to target of 700kg weight through added mass option

• Added mass will be opened by following (Load Case >> Added Mass) process. In Added Mass, new mass will be created with Type 1 (Mass is disturbed to each node of node group).

• After Type 1, assign added mass with required kg mass and then (Right click>> select in graphics >> Add/Remove node by picking selection) as per the different components which are not available inside the car model. The mass will be added at five different locations of the car model in order to transfer center of gravity at the desired location to stabilize it.

   Weights Distribution on Car to balance COG

• Driver and his seat weight as 70 kg mass is added.

• passanger and his seat weight as 70 kg mass is added.

• Fuel tank weight as 100 kg mass is added.

• Dashboard weight as 20 kg mass is added.

• Auxiliaries weight as 274 kg mass is added.

• Below Images shows that 700kg weight target and transferring centre of gravity at the desired location has been achieved by adding mass at the different location of the car model in order to compensate absent components.

Export HyperCrash File in HyperMesh:

• After making necessary changes in the HyperCrash, file will be saved as neon_front_car_crash_0000.rad by following (File >> Export >> Radioss).
• Import HyperCrash file in HyperMesh by following the (File >> Import) process.

Contact Interface:

  Interface Type7: Nodes to Surface Contact

• It is the node to surface contact and it is a universal type of contact.
• A gap is defined around the master segment and slave nodes and this gap can be variable or constant.
• The slave is kept outside of the master gap by resistive force application.

Recommended Type 7 Options:

                    

• As we are considering self-contact for the car model, slave and master segments for this type 7 contact for the entire car model. The selection of all components under the slave and master segments respectively are given as below

Rigid Wall:   

• Now Rwall window frame will be created by following (Solver >> Right Click >> RWALL>> CYL) process.

• The node will select on the corner of the front side door of the car model.
• The side pole is facing opposite to the side door of car model with normal to the z-axis representation. When slave node comes in contact, frictional parameter will be provided for the car model.
• In support frame, slide of sliding with friction and coulomb friction of 0.1 will be provided. D-search basically distance for secondary search represents all the node within the range of d-search distance considered as slave node for the contact between the rigid wall and car model with value of 1000 m. The diameter of side pole will provide with value of 254 mm.

 Initial Velocity:

•  Initial velocity will be opened by following (Solver >> Right Click >> Create >> BOUNDARY CONDITIONS >> INIVEL) process.

• Basically, initial velocity of the car model mentioned in kmph unit but it is necessary to convert into ms as per the neon_side_reduced_0000.rad file. So, the value of initial velocity is 35 kmph and after conversion it becomes 15.6464 ms.

• Initial Velocity of Translational material velocity type and all the node of 95 components will be considered for propelling of entire car model against the side pole.

• Below images shows whether all nodes have been selected or not which can be reviewed by following (INIVEL >> Right Click >> Review) process.

Sectional Forces:

• The purpose of crashing the car against the rigid wall lies on the concept of sectional force which creates huge impact on the passenger inside the cabin. In this project, section will be created on the different parts of the car model like Cross Members to understand the sectional force on them so that to ensure the safety of passenger inside the cabin.

Frame Creation:

• Before creating sectional forces, the frame will be created for components of car model by following (Solver Browser >> Right Click >> FRAME >> MOV) process.

• Below image shows that local axis coordinate will be created and followed by node creation in origin position, along the z -axis and y-z plane with relative size of 50mm to get picture clearly.

•  Below images shows frame created for the Cross Member 1 and now sectional force will generated for it.

• The section will be created for components of car model by following (Solver Browser >> Right Click >> SECT >> SECT) process.        

• For Cross Member, local coordinate axis of that particular component will be selected by FRAME_ID with delta T of 0.1 and alpha of 0.67.

• Inside grshel_id, particular elements will be selected with specified three nodes aligned to each other on the Cross Member.
• sectional force created for the Cross Members and Pillars of the car model.

Intrusion Spring:

• Spring elements is created to understand intrusion which means how the forces are coming inside the cabin during deformation. It is opened by following (1D >> springs) process.

• After creating spring elements, properties will be applied to them with mass of 0.0001 kg and stiffness of 0.001 kg/mm.

 Peak Velocity at Inner Node of Car Door:

• The node will be created on the inner portion of car door by following (Solver>>TH>>NODE>>Locates at Inner Node of Car Model) process.

Delete TH cards create new TH cards:

• Deleting all unnecessary Time History files already present when file imported in the HyperMesh.
• Creating Time History files for the operations done above for Node, Type 7, RWALL, and all components sectional forces by following (Solver Browser >> Right Click >> TH  >>INTER >>NODE>> RWALL >> SECTIO >> SPRING) process.

Edit Cards:

DT Cards:

• DT cards will be created by following (Solver Browser >> Right Click >> Create >> ENGINE KEYWORDS >> DT).
• The time tolerance for stop criteria of 0.9 and minimum time step of 0.0001 will be provided.

RUN Cards:

• Run cards will be created by following (Solver Browser >> Right Click >> Create >> ENGINE KEYWORDS >> RUN) and the final time run of 80ms will be provided.

 Model Checker:

• After editing cards required for the simulation of car model, error will be checked if any present or mistakes done from the user side for leaving essential values or operation to be performed before running the simulation of car model. It is achieved by following (Model Checker >> Radioss Block) process.

• Run check on the right side of model checker window frame will be selected in order to run operation to check where the error present inside the model or mistaken done from the instructor side.

• After running the operation to check error, now whatever the error present inside the model will be inspected and rectified it according to the conditions.
• Now necessary errors which are creating major problem for running simulation of car model has been removed.

Vehicle Simulation Setup:

• Radioss options will be opened by following (Analysis >> Radioss) process. In Radioss option, file will be saved in desired folder with desired file named as ‘001.out’ which gives energy, mass error and other important properties.
• The expert options, run options, run number will be maintained as all, analysis, 1 and other option as -nt 4 throughout the base simulation.

• After completing the simulation,the radioss will pop up a solver window stating Radioss Job Completed which indicates the simulation has been completed.

Post Processing :

Review the Simulation using HyperView :

• Hyperview allows for loading and viewing result files obtained from several sources.
• Based on the solver type of the files and the results you would like to visualize and analyze,there are differnt ways to load the input deck and their corresponding results into hyperview.
• Import the animation file .h3d into the hyperview.

Animation:

VON MISES:

DISPLACEMENT:

Check for the Intrusions :

• After running the simulation,We have to check for the intrusions.
• To check for the intrusion,Measure the distance between the springs where we created.
• To measure,Go to Measure tool from HyperView and select the end node of the springs to know the distance between.

Before collision:

After collision:

 Intusion at Fuel Tank Region :

• After defining the nodes at the end of the spring at the initial position before the collision,The magnitude for the spring is 1298.469 mm.
• After defining the nodes at the end of the spring after the collision,The magnitude for the spring is 909.090 mm.
• Intrusion [Spring] at Fuel Tank Region is 1298.469-909.090 = 389.379 mm.

Intusion at B-Pillar Region :

• Before the collision,The magnitude for the spring is 1445.749 mm.
• After the collision,The magnitude for the spring is 954.203 mm.
• Intrusion [Spring] at B Pillar Region is 1445.749-954.203 = 491.546 mm.

 Intusion at Hinge-Pillar Region :

• Before the collision,The magnitude for the spring is 1356.421 mm.
• After the collision,The magnitude for the spring is 1318.398 mm.
• Intrusion [Spring] at Hinge Pillar Region is 1356.421-1318.398 = 38.023 mm.

 Plot the graphs using -Hypergraph 2D :

Intrusion Graph:

Fuel Tank Region:

• In the beginning,the length of the spring was 1298.469 mm. and after when the car crash the pole,the length of the spring is 9909.090 mm..So the total deflection of this spring is 389.379 mm.

B-Pillar Region:

• In the beginning,the length of the spring was 1445.749 mm and after when the car crash the pole,the length of the spring is 954.203 mm.So the total deflection of this spring is 491.546 mm.

Hinge-Pillar Region:

• In the beginning,the length of the spring was 1356.421 mm and after when the car crash the pole,the length of the spring is 1318.398 mm.So the total deflection of this spring is 38.023 mm.

Peak Velocity :

• When the car hits the pole,the door will be deformed,So due to the deformation,the inner portion of the door will hit the passengers inside the car and it may cause severe injuries to the passengers.
• So it is important to calculate the peak velocity at the door region.
• The peak velocity of the node on the door is 9.2 m/s.The graph is in Zig-Zag form,Due to the noise and vibration,When the the car hits the pole.
• We gave the initial velocity as 8.94 m/s,But in the graph,the initial velocity is 9.2 m/s,It's increased little bit,Because due to inertia.

Interface [TYPE 7] :

• Here the interfaces curve starts from origin and reaches peak due to collision.
• And it increases & decreases before it reaches to peak value,Cause there will be a contact forces acting with in the car before collision.

Sectional Force at Cross Member 1 :

• The maximum sectional force on the Cross Member 1 is 5.7 KN.

Sectional Force at Cross Member 2 :

• The maximum sectional force on the Cross Member 2 is 8.9 KN.

Sectional Force at A Pillar :

• The maximum sectional force on the A Pillar is 0.475 KN.
• Here for this Cross Member,the sectional force is very low when compared to the previous two Cross Members.

Sectional Force at B Pillar :

 

• The maximum sectional force on the Cross Member 3 is 0.44 KN.
• Here for this Cross Member,the sectional force is very low when compared to the previous two Cross Members.

 Internal Energy :

• Here the internal energy is in Zero,Because there is no deformation initially,So the internal energy is in Zero and starts from Zero and goes on increasing.
• The internal energy increases because the deformation is happening,there is a displacement,So the internal energy increases,when the displacement or deformation occurs.

 Kinetic energy: 

• Kinetic Energy is at peak in the starting,Why because,we have huge mass.
• Kinetic energy is lower and decreases,why because,there is a velocity applied to the car component,so its getting deformed and the kinetic energy decreases.
• The kinetic energy will decrease due to the decrease in velocity after the collison,When the car hits the rigid pole. So,the kinetic energy decreases with respect to time.

Contact Energy :

• Here the contact energy starts from origin,Cause the Car is in intial condition.
• Intially there is no contact between the Car and Rigid Pole.
• There is also no deformation intially,But when the car goes and hits on the rigid pole,The contact energy starts increasing.
• When the deformation or displacement happens to the car,the contact energy increases,cause the car component comes within the contact to the rigid pole.So the contact energy goes on increasing.

Total Energy :

• Here total energy starts from higher value,In starting itself its increasing,Why because the total energy is sum of  Kinetic Energy+Contact Energy+Hourglass Energy + Internal Energy.

Hourglass Energy :

• Here the hourglass energy is less than 5% of internal energy,So it is fine.

Final Image :

Result:

• Here the COG from the initial position has been changed to the required position by mass balancing.
• Hence the penetration and intersections has been verified successfully.
• Hence the interfaces created newly.
• Hence the peak velocity has been given to the inner node of the door.
• Hence the initial velocity was assigned.
• Hnece the rigid pole was created successfully.
• Hence the springs were created to obtain the intrusions.
• Hence the TH for all inputs were cretaed inorder to obatined otputs.
• Hence the simulation was runned successfully without any errors.
• Atlast all the graphs were plotted with the obtained results.