Assignment 7
OBJECTIVE :
To Conduct a Simulation of a Side Crash of the provided Dodge Neon BIW onto a Rigid Pole based on the guidelines listed below :
- Should follow corresponding FMVSS Standard
- 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.
- Create rigid wall with friction 0.1.
- Compare the model weight with the reference 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:
i) Sectional Forces in Cross Members.
ii) Intrusions at
- B Pillar
- Hinge Pillar
- Fuel Tank Region
iii) Peak Velocity of inner node of the door.
Create a Report and comment on how to help reduce fuel tank intrusions.
CRASH STANDARD :
For the Side crash analysis of a vehicle body onto a rigid Pole, FMVSS 214P is followed.
Link for Standard : https://www.nhtsa.gov/sites/nhtsa.dot.gov/files/tp214p-01.pdf
The following points are noted for the current simulation :
- Diameter of the Rigid Pole : 10 inches (or) 254mm
- Setup and Working of Simulation :
STUDY OF PROVIDED FILE :
File 1 : Full Car Model
From the above file, we only require the value of total Mass of the vehicle and the location of the center of gravity :
Using the Mass Balancing Toolbar in Hypercrash UI, Both of the required values are checked as shown below :
Mass of the Vehicle : 1216.55 kg
Center of Gravity (C.O.G) of the Vehicle :
The C.O.G was found to be near the transmission tunnel region as shown below :
File 2 : Partial BIW
- On first look, it is noted that The provided model contains 95 Components each described by an unique property but is defined using only 94 material cards.
- Additionally, there are 298 Rigid bodies defined across the components, with most Rigid bodies being defined for very few nodes. This can be attributed to the need for replicating the actual way in which the nodes should behave.
- Also, there are 7 contact interfaces, which on closer look can be deleted as it is not required for our current simulation.
- It is also noted that there are 58 additional masses defined, each with a significant value and hence need not be deleted.
- Addionally, another observation that was made was that, one component (Door Lock) had been defined with a Solid property Card and a Elastic (Type 1) material card. The others components are surface components defined by Shell or SH4N property cards.
SIMULATION :
- As per the provided guidelines, the system used for this simulation is [kg], [mm], [ms] unit system.
- As discussed above, once importing the system into the Hypercrash UI, the unnecessary datas are deleted.
Pre-Processing :
i) Setting up of Interfaces :
- Based on the provided guidelines, it is clear that only 1 interfaces is required.
* For Self Contact between the Parts : A self impact Type 7 Contact with all Parts selected.
ii) Setting up a Rigid Cylindrical Pole :
- A Rigid cylindrical pole was setup on the Global XY plane and in line with the requirement of FMVSS 214P.
iii) Defining Additional masses to meet Target weight and C.O.G Requirements :
As per the guidelines provided, it is required for the setup to weight around 700g with the C.O.G at optimum location as mentioned.
- The current weight of the provided model is checked using the Mass Balancing option in Hypercrash
The mass is found to be 166 grams with C.O.G near the Cross Member
- Hence, additional mass of 534 grams should be added to the BIW using the added mass tool.
- The location of C.O.G and Weight of the C.O.G after mass addition is shown below :
iv) Defining an Initial Velocity to the Nodes :
As per the guidelines provided, an initial velocity of 35mph should be provided to all the nodes in the positive y-direction.
Since the current units is mm/ms, the mph needs to be converted before entering in UI.
35mph = 15.646 mm/ms
v) Check for Penetrations :
Using the Check penetration tool available in Contact Interfaces tab in Hypercrash UI, the system is checked for any initial penetrations.
vi) Defining Sections to measure required sectional Forces :
The Sectional Forces along both the Cross sectional members are required as per the guidelines, hence sections are created normal to the Global Y-Axis.
vii) Control card Definitions :
Currently, 17 Control cards are defined. They are :
- As per the guidelines the Run time and Time frequency to write data on history plot file T-file are checked in the RUN card and TFILE Card. The required values of 80ms run time and 0.5ms T_freq are present already, hence it is not changed.
- Additionally another control card is defined /ANIM/VECT to animate the Displacement, stresses etc while Post-Processing. The following outputs are requested.
viii) Time/Data History Definitions :
On top of the existing 2 Time history requests, TH of Interface, Section and Rigidwall are created.
ix) Setting up for Peak Velocity Measurement of Inner Node on Door :
To measure the Peak velocity of the required node, we set up a seperate Time history Request (/TH/NODE) as shown
x) Setting up for Intrusion measurement :
To measure the intrusions of the nodes at
- B-Pillar
- Hinge Pillar
- Fuel Tank Region
A seperate Time history Reques (/TH/NODE) is setup with respect to an user defined moving skew, in this case on the nodes on the opposite Rocker
xi) Model Checker :
Model checker available under Quality tab in Hypercrash UI is used to check the model as shown below
- According to the model checker, 6 warnings are present in the current system.
- On closer look, The warnings are not severe and can be ignored as they are generated from unused cards.
*Once the Pre-processing is done in Hypercrash, The system is exported to be solved in RADIOSS.
Post-Processing :
The Engine output file is opened using Notepad to check if the Energy and Mass Errors in solution is Acceptable.
- From the output file, we can see that the maximum Energy error is -1.2% on the system (Maximum Acceptable value is ~ -5%), hence it is acceptable
- The mass error of the system is 0.008746 which is also acceptable.
Hence it is clear that the above system can be post-processed further.
i) Animation of The Crash :
Displacement Plot -
Stress Plot -
ii) System Plots
Rigid Wall Force vs Time -
Max. R.Wall Force : 53.62 kN
Mean R.Wall Force : 34.76 kN
Energy Plots vs Time -
| SI.No. | Energy Type | Maximum Value | Mean Value |
| 1 | Total Energy | 86308.32 | 85561.74 kJ |
| 2 | Kinetic Energy | 86308.32 | 75504.3 kJ |
| 3 | Internal Energy | 18665.47 kJ | 10057.44 kJ |
| 4 | Contact Energy | 915.57 kJ | 495.55 kJ |
| 5 | Hourglass Energy | 92.72 kJ | 44.08 kJ |
iii) Sectional Forces in Cross Members
Upper Cross Member Sectional Force vs Time -
Max. Sectional Force on Upper Cross Member : 5.02 kN
Mean Sectional Force on Upper Cross Member : 1.736 kN
Lower Cross Member Sectional Force vs Time -
Max. Sectional Force on Lower Cross Member : 4.77 kN
Mean Sectional Force on Lower Cross Member : 1.966 kN
iv) Intrusions of Required Parts
B-Pillar Intrusion :
Max. Intrusion : 194.08 mm
Hinge Pillar Intrusion :
Max. Intrusion : 398.32 mm
Fuel Tank Region Intrusion :
Max. Intrusion : 400.95 mm
v) Peak velocity of inner node of the door.
Max. Velocity : 16.26 mm/ms
REPORT :
The Datas were compiled onto a presentation and is attached at the end. Screenshots of the same are shown below :
CONCLUSION :
- Thus the Side Crash Analysis for the provided Dodge Neon BIW was conducted as per provided guidelines.
- To reduce The Fuel Tank intrusions, Additional Cross members or Anti-Intrusion Bars could be used.
All relevant datas are attached in the link shared below :
https://drive.google.com/file/d/1pRzDiNhA_o975p7ZJy2mNFsTGFmBVBpq/view?usp=sharing