Assignment 6-Frontal Crash Simulation Challenge
Objective:
To perform a crash analysis on the front of a BIW, also known as a front crash. The analysis is to be carried out for deformation and the forces created as a result of the crash at a speed of 35 mph.
The aim is to simulate for following problem statements;
- 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.
Procedure:
Import the model:
Import the '.rad' starter file of the model,' neon_front_0000.rad' in Radioss using Import Solver Deck option.
Unit System:
For units, browse
Model > Cards > BEGIN_CARD
Mass unit : kg
Length unit : mm
Time unit : ms
Penetration and intersection:
Zero penetration or intersections found.
Reach the target weight of 700 kg while getting CG about the required range:
To 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. The given model was less in mass with 188 kg. Check by using Tools > Mass Details > Mass, cog and inertia and check the mass.
Existing weight of mesh geometry: 118 kg
Required weight : 700 kg
Additional mass to be added: 582 kg
To add additional weight to achive the required weight ,
Solver > addmas
following is the achived COG location,
Applying initial velocity:
solver > create > boundary conditions > inivel
the velocity need to be applied is 35Mph,
since, the units are kg mm ms , thefore the value to input is 15.65mm/ms
Contact interfaces:
Solver > inter
A type7 contact is created between all the 95 components with friction coefficient as 0.2,
Rigid wall (wall):
To create a rigid wall at the front side of the car, creat the outermost node at the front of the car. Using temp nodes option.
Then right-click in
solver browser and navigate to Create > RWALL > Plane
In the RWALL panel, under Engineering data specify the coordinates of the wall.
Select a node at the front bumper and set the at xm, ym, zm by selecing a node and add a normal reaction to the wall as -1 for the reaction.
The FRIC value will be 0.1 and search value will be 2500 as shown below.
The rigid plane wall created is displayed below;
Cross Section:
For the required results cross sectional is created which are calculated based on a frame of reference. So before creating cross section,create moving frames on a particular node of that section. Now as the moving frames is created which are also called as local axis, the local axis needs to be aligned to the global axis.
Once the moving frame is created,next step is to create cross-section for the frame. To create a cross-section,right-click on the Solver browser, navigate ,
Create > SECT > SECT
In section panel, specify the Frame_ID.
Right click and create grshel _id on the same panal, select the elements where the cross sectional is required for appropriate results.
Frame created is displayed below;
similar process can be followed for different crossections and results;
Intrusion measuement setup:
Here, its asked to find the intrusions at node provided with respect to car body. So to find the results at the specified parts, create spring between the node provided and the base cross member of car, for creating spring;
1D > SPRINGS > SPRING2 , select 2 nodes;
Create the property card for spring with spring stiffness 0.0001
Time History Plot:
For springs , creat spring plot in output th plot similarlyfor rigid wall, sections and nodes.
the created th plots are displayed below;
Time step and Run time:
The run time is kept to be 80ms;
in ENG_DT_NODA, Tmin is kept to be 0.0005 micro second as shown below,
Symulations setup is displayed below ;
Symulation run:
Now, the model is ready for symilation,
before running the symulation the model is checked using radiossblock , to check ;
Tools > model checker> radiosblock
once the check is successfully done the model is ready to run for analysis.
the symulation was run successfully with zero errors and warnings with run time 2:00:56,
Results:
Elapsed time is 1hr 14mins with error as -1.7%, 0.1667e8 as internal energy, 0.6730e8 as total kinetic energy and 0.197e-3 as mass error.
Max stress of 321Mpa is found
Von Mises Stress counter plot:
Sectional force in the rail at location of indicated node 174247.
The sectional force experienced at node 17427 is 15160N.
Axial force received on the rails from bumper:
Axial forces received on the rails from bumper is 19837N .
Shotgun cross sectional forces:
Right shotgun plot from rear view of car;
on the right shot gun the maximum resultant force experienced at cross section is 8722 N.
Left shotgun plot from rear view of car;
on the left shot gun the maximum resultant force experienced at cross section is 5297 N.
A pillar cross section:
Left A-Pillar plot from rear view of car;
on the left A-Pillar the maximum resultant force experienced at cross section is 769.50 N.
Right A-Pillar plot from rear view of car;
on the right A-Pillar the maximum resultant force experienced at cross section is 839.50 N.
Acceleration curve received on the accelerometer at base of B pillar:
Right acceleration plot from rear view of car;
on the right base of B pillar the maximum resultant acceleration experienced is 0.511 mm/ms^2.
Left acceleration plot from rear view of car;
on the left base of B pillar the maximum resultant acceleration experienced is 1.772 mm/ms^2.
Intrusions on the dash wall 66695,66244:
total intrusion at node 66695;
total intrusion at node 66695 is 129.2mm.
total intrusion at node 66244;
total intrusion at node 66244 is 86.33mm.
Conclusion:
The given model was simulated for the frontal crash using Radios and the results obtained were validated.The hourglass energy is less than the internal energy. The graphical results were plotted for all the test cases. From the simulation, it can be observed that there was minimum deformation in the cabin, and also minimum intrusion was found in the driver's seat area.