Assignment 6
OBJECTIVE: To perform frontal crash analysis on a Given 100k Node model in hypermesh after perfomring certain pre simulation checks.
SOFTWARE USED: Hypermesh RADIOSS and Hypercrash
PROCEDURE:
1. Load the file in hypermesh radioss workspace and import the solver deck file onto the workspace.
Figure 1: Model Imported
This is the model imported into the hypermesh workspace.
2. Now we need to perform some pre simulation checks.
a. Check unit system and either follow[Mg mm s] or [Kg mm ms]
Figure 2: Unit system check
b. Create appropriate interface ,friction 0.2 and recommended parameter
Figure 3: Contact interface 1
Figure 4: Contact interface 2
c. Penetration check
Figure 5: No penetrations
d. Rigid Wall Creation
Figure 6: Rigid Wall Created
e. Perfrom mass balancing to achieve 700 kg weight with proper CG of the vehicle
This was done in hypercrash with the help of the mass balancer module given.
Go to the toolbar, MASS-->Balancing
Figure 7: Mass balancing
f. Initial Velocity
Figure 8: Initial velocity applied
g. Runtime change
Figure 8: Time step change
Results
Figure 9: Von Mises Stress
Figure 10: Energy Graphs
From the above graph we can observe that the kinetic and internal energy converge at a point in the crash. This is due to the fact that the velocity of the vehicle decreases while the impact is still on and thus internal energy increases. We can calculate and find out the kinetic energy with the simple formula as we have modelled the mass and velocity in the simulatuion.
Figure 10: RWALL force Normal
We can see the fluctuation of the normal force due to the contact of the rigid wall with the vehicle. We can notice that at the start the force changes and so does in the most part of the simulation. This is due to the fact that the vehicle parts act differently to the rigid wall and a cummlative graph is presented by RADIOSS.
Figure 11: Section force on left rail section
Figure 12: Displacement on intrusion 66244
Figure 13: Left side A pillar Normal Force
Figure 14: Right Side A Pillar Normal Force
Figure 15: Shotgun Forces
Figure 16: B Pillar Accelerometers
CONCLUTIONS:
As per design BIW structure works to dissipate the impact energy by crumpling/crushing as well as transfers it around the occupant chamber such that least damage s done to be passengers and driver in case of a crash. As the given model is only a part of the complete assembly as in the 300k element model many of the important components such as engine and transmission in case of a front-wheel driven vehicle, steering and suspension system body parts etc are not involved which in real-life conditions will dissipate more of the impact energy lowering the impact forces further hence the results are satisfactory.
With the help of Added masses and mass balancing done in Hypercrash we have utilized the mases of the various parts like engine and transmissions.
The Link for the files is : https://drive.google.com/drive/folders/1kdHGsZQA5st5IR8e0b2JTfpifQ2bN1qK?usp=sharing