Assignment 6-Frontal Crash Simulation Challenge

AIM: Perform a Frontal Crash Simulation on the given car model  with the recommended parameters and requests.

OBJECTIVE: 

Frontal 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 penetrations and intersection.
• Correct rigid bodies if any issues.
• Create rigid wall with friction 0.1.
• 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.
• Initial velocity 35 mph.
• Use model checker to ensure good quality.
• Time-step :0.5 to 0.1 microseconds.
• Run 80 ms.

Output requests:

• Sectional force in the rails at location of indicated node 174247.
• Axial force received on the rails from bumper.
• Shotgun cross sectional forces.
• A pillar cross section.
• Acceleration curve received on the accelerometer at base of B pillar (on B pillar rocker).
• Intrusions on the dash wall 66695,66244.

CASE SETUP AND EXECUTION:

Import the given .rad file using Import Solver Deck option. Figure1 and Figure2 shows the imported models.

 Figure1

 Figure2

• Check unit system and either follow[Mg mm s] or [Kg mm ms].

To check unit system Model>Cards>Begin_Card. Unit system for this model is [kg mm ms] which is shown in Figure3.

Figure3  Figure4

• Create appropriate interface ,friction 0.2 and recommended parameters.

Since all the components of a model is self-impacting or the nodes and elements of the model will have a contact between we can create a Type7 interface. To create interface Solver Browser>Create>Inter>Type7 shown in Figure4. For Grnod_id(S) and Surf_id(M) select all the components as shown in Figure5 and select the recommended proprties and friction 0.2 as shown in Figure6&7

Figure5

 

Figure6                                                                     Figure7

• Make sure of no penetrations and intersection.

To check for penetrations and intersections in the model, go to Tools menu on menu bar and click on penetration type for penetration check and intersection type for intersection and select components for entity type and select all the components as shown in Figure8,9&10.

  Figure8  

Figure9                                                                   Figure10

• Create rigid wall with friction 0.1.

To create a plane rigid wall with friction 0.1, front side of the car. we need to create a plane for that we need a node from where at a distance the plane is created. By usin temp nodes option we will create a temperory node at the outermost of the bumper of the car as shown in Figure11. To create rigid wall Solver Browser>Create>Rwall>Plane. For the location of rigid wall we will click on the node ehich we created and then give a gap of 10mm in X-axix because the wall must not be connected to the mode and select the remaining parameters as shown in Figure12. Figure13 shows the model having rigid wall.

Figure11

Figure12  Figure13

• 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.

First check the mass and COG of the given model in Hypercrash for better visualization as shown in Figure14.

Here we will see that the mass of model is around 188 Kg and centre of gravity nearer to the place of pedal but that is not in main vehicle so we need to change the mass of vehicle to around 700 Kg inorder to get the COG of the model behind the driver sheet middle of the model.

To do that goto Solver Browser>Create>ADMAS. Select Mass is added to each nodeof node group, selected ten node and added mass of 51.2 to each node inorder to total mass 700 (188+(10*51.2)) and nodes are selected in such a way that the COG of the model located behind the driver sheet as shown in Figure15. Figure16 shows the mass and COG location in Hypercrash.

Figure14

Figure15

Figure16

• Initial velocity 35 mph.

To create Initial velocity Solver Browser>Create>Boundary Conditions>Inivel. Select all the components as the Entity for grnd_ID. We will give the initial velocity of 35 mph or 15.64 mm/ms in X-axis and as the velocity should be translational velocity, we will select TRA option in type as shown in Figure 17and18.

 Figure17  Figure18

• Cross Section

To create cross sections where we will be calculating the results, we need to create a frame of reference at that location. The created moving frames which are also called as local axis have to be perfectly aligned with the global axis. So for this we will extract the node location or coordinates of a particular node on the section in Nodes panel, then we will offset the node in X-axis by 10 units and create a new node. Similarly we will offset the node in X-axis by 10 units and create a new node. Similarly we will offset and create a node in Y-axis as shown in Figure19 and 20.

Figure19

Figure20

We can use these nodes to create moving frames, Solver Browser>Create>Frame>Mov. Select the frame by node reference by selecting origin node and selcting the offset nodes for X-axis and XY-plane and click on create as shown in Figure21.

Figure21

After creating a moving frame then we have to create a cross section, To create cross section Solver Browser>Create>Sect.

In section panel, we will specify the Frame_ID as the moving frame which we created and remaining values as shown in Figure22 and 23.

Figure22

 Figure23  Figure24

Similarly we will create cross section on both left side and right side of the given car model at different locations as shown in Figure24 and 25

 Figure25

After creating the cross sections, we have to request the results at the cross sections that we created. For this Model Browser>Output Blocks>Create. Select crossseections at the Entity IDs by this we are able to plot graphs of the cross sectional forces in HypeerGraph as shown in the Figure26.

Figure26.

In the same way we will create the output blocks for the remaining cross sections.

• Accelerometer

We have to measure acceleration of the pillar during the crash. So we will create accelerometers on the pillars. To create accelerometer, Solver Browser>Create>Accel. To Select node_ID, select at the node where we want acceleration result and specify F_cut value as 1.65 on both sides of the pillar as shown in Figure27 and 28.

Figure27

 Figure28

• Intrusion

Here, we need to find the intrusions on the dash wall at noe 66695 and 66244 respectively. So to find the results at the specified nodes, we need to have a frame of reference. Thus we will create moving frames at seat reinforcement part which is shown in the Figure29.

Figure29

Then to get the results in HyperGraph we will create output blocks for the intrusions by specifying the node and the frame or skew based on which the intrusions are calcuated as shown in Figure30.

 Figure30.

• Time step and Run time

To check the run time, Model Browser>Cards>ENG_RUN>Tstop=80ms.

To check the Run time, Model Browser>Cards>ENG_DT_NODA>Tmin=0.0005 ms.

• Model Checker.

To check the quality, Menu Bar>Tools>Model Checker>RadiossBlock. 

after clicking on RadiossBlock new model check browser will open in which if we click on Run Checks command which is at the top right side it will show all the errors the click on Auto Correct box in which the software automatically perform the possible corrections and give a green tick in status bar as shown in Figure31 and 32.

Figure31

Figure32.

Run the simulation.

• Result and Simulation

First we will check the energy error and mass error for this we have to open the engine.out file of the model and check the last column for energy and mass error as shown in Figure33.

Figure33

Energy Error : -1.3%

Mass Error : 0.9992E-03

Total number of Cycles : 160001

Total runtime : 11105.05s

To visualise the animation results we can navigate to HyperView section in which we will import .h3d file and load the model, Here we can able to simulate and animate the results of the model.

Crash simulation files are uploaded as video1.mkv, video2.mkv and video3.mkv. 

The deformations in the model is unrealistic since the given model is not complete at the same time i added the extra mass to ten nodes inorder to increase the total mass of the car which is totally responsible for this unrealistic deformations in the car 

To view graph result we can directly shift to HyperGraph 2D in which we will load the T01 file and plot the results for different parameters which is shown below Figures34,35&36.

Figure34,

Figure35

Figure36,