hexagon logo
Register Sign in
  • State Not Answered
  • Replies 19 replies
  • Subscribers 11 subscribers
  • Views 475 views
  • Users 0 members are here
Options
Related

Is there any easier way of making tire blow out simulation?

yahya.oz
Hi,
I am trying to run a tire blow out simulation. I made some research and it seems the easiest way to use Ftire with inflation pressure around 0 bars.
I got an ftire data with pressures with the tire tests were performed at 8.5 and 10 bars.
I would like to get your opinions about making the analyses with the extrapolation form 8.5 to 10 bars to 0 bars inflation pressures would be realistic or not.
During my research I couldn't find any study with Adams in tire blow out analyses, have you seen any study on tire blow out analyses in Adams? Is there any easier way?
Regards,
Yahya,​
  • 0
    Hi Yahya,
     
    yes, FTire can be used for tire blow-out. There are different ways to prescribe the respective inflation pressure time history; please have a look at FTire's docu.
     
    Unfortunately, up to now we do not have respective measurements that can serve as an accuracy indicator. However, from the *physics* point of view, FTire's approach is definitely realistic.
     
    FTire comes with some hardcoded residual internal structural stiffnesses at p=0 (see docu). To start with, I propose to use only *one* of your stiffness values and rely on the interpolation method between this respective stiffness and the residual stiffness.
     
    Michael
  • 0
    Hi Michael,
     
    Thank you for your answer. ​I have get in touch with Heinz (cosin) yesterday and we started the discussion via email.
     
    The only option (that  I could find in Ftire docu and Adams docu) of entering the time dependent inflation pressure time history to the MBD and also tire model is  "operating conditions" block.
     
    $--------------------------------------------OPERATING_CONDITIONS
    [ OPERATING_CONDITIONS]
     
    According to documentation I understand that I neet to delete : 
    inflation_pressure =
    part and enter:
     
    ( TIME_TABLE_INFLATION_PRESSURE)
    0 2.2
    5 2.2
    5.2 1.2
     
    part.
     
     
    What are the other options? I might prefere other options because even modifying Ftire's ".tir" file by a text editor (like notepad++)  is not supported and using cosin/tools  is supported due to ascii format of .tir file, I need to use a text editor to enter time table by a text editor since sosin/tools doesn't support entering time dependent inflation pressure.
     
    If there is no other option, would it be possible to send me and example "OPERATING_CONDITIONS" working  block that I can paste to me .tir file. I got two alternative text editors to nodpad for editing .tir file: Notepad++ and EditPad Pro.  It would be greate if you can send the file saving steps to keep Ascii format.
     
    I would be glad if you can further explain your suggestion of using only *one* of my stiffness values. I got to datas for 8.5 and 10 bars but when I set the inflation pressure to zero, according to my understanding from docus, these two pressure data won't be used and only the data in the rim misuse block will be used in the dynamic calculations (please, please correct me if I am wrong. I just concentrated on Ftire model):
     
    $......................................................rim misuse stiffness data
     rim_flange_contact_stiffn =      -----               $ N/mm
     rim_flange_contact_stiffn_progr = ----                   $ %
     rim_to_flat_tire_distance =      --                    $ mm
     rim_to_road_contact_stiffn =     ---                   $ N/mm
     rim_to_road_contact_frict_coeff = ----                   $ -
     
     
     
    Again thank you for your help.
     
    Regards,
     
    Yahya 
  • 0
    Who told you that you aren't allowed to edit a .tir file ? Didn't knew that alternative facts are already taking over the simulation world ....
     
    Seriously: I do that all the time and it's not important which editor you you use.
     
    Just delete the last part that says
    $............preprocessed data (do not edit); cosin software version r14590 used
     preprocessed_data =
     
    If you don't have contact stiffness in your file, yet, then be careful with the values.
    Defaults are much too high which will end with a tire shooting off to space or an aborted simulation. In passenger cars something in the few hundred to low thousands is realistic.
    I have a tiretestrig plugin that should be available @ Scania. Use "Run vertical stiffness test" to obtain the attached plot.
    FTire_auf_Felge_druecken
     
    If the tire is in a database you aren't allowed to write to: Copy it to one of your own databases and use the modified clone.
    If it works as expected, send it to the database admin and tell him to put the new file in the public database.
     
    Another way to skin the cat:
    Use a GCON instead of a revolute joint (or a dummy part + a GCON) to constrain the wheel to the suspension upright. In that GCON you can use something like if(time-x: DXYZ(i,j),0,0) which will make the whole tire "coming loose" from the vehicle at time x. Not 100% what you wanted, but definitively the worst case and works with any tire model.
     
     
  • 0
    Thank you Martin,
     
    Adams documentation and cosin/tool documentation told me. I know I can modify every .tir document can be modified with my old friend notepad, but since both of these documents insists to use cosin/tool, I would like to ask.
     
    Actually your suggestion didn't solve my problem. ​ I deleted thelastpart including gibrish data at the end of document and  I made the  following modification to operating conditions as stated in the Adams and cosin/tool documentation:
     
    [OPERATING_CONDITIONS]
     MODEL_LEVEL = 7
     ( TIME_TABLE_INFLATION_PRESSURE )
     0    8.5                   $ bar
     2    8.5                   $ bar
     2.2  0.0                   $ bar
     
    but it is still runnung without any blow out. Most probably I found a bug that time table doesn't work.
     
    Did you get the graph in your documentation in quasi equilibrium. I need to change the inflation pressure in dynamic simulation. Can you showme the inflation pressure w.r.t. time graph?
     
     
     
    I found "ctiSetInflationPressure" routine for Ftire. May be I can modify the pressure within Adams. But I need to find out how I can compile with this routine.
     
     
    Thanks,
     
    Yahya
  • 0
    I guess the block is not proceeded because you may need to activate that with one of the other switches (activate_xxx_model) in the [MODEL] block.
    I'd leave it to the cosin support to instruct you what exactly to change (or fix the bug, if there is one)
     
    My plot was NOT done with changing pressure. It's solely to show you the effects of pressing a tire on a flat surface with rubber/rim/road coming into contact (which is what you have on a tire without pressure)
    The point where this occurs is mainly determined with rim_to_flat_tire_distance and the steepness after contact mainly depends on rim_flange_contact_stiffn & rim_flange_contact_stiffn_progr.
    If you press even further the rim to road contact becomes active and adds rim_to_road_contact_stiffn.
     
  • 0
    Just to add some more information:
    • I tried to add the block you proposed to the demo Ftire (205/55R16) from the acar_shared. As expected it had no effect
    • BTW: The latest FTire 2019-1 was used and there was no use_updates_prior_to set that would prevent it from using the latest enhancements.
    • After switching on all the existing activate_xxx_model parameters it still didn't show any signs of loosing pressure at the given time.
    • Unfortunately when trying to RTFM, I found there actually is no manual on the designated site www.cosin.eu/.../ (Seems someone took the old version off and did not upload the latest one ....)
  • 0
    sorry, I've been pretty busy in the last days. I'll look now into the issue and let you know asap.
  • 0
    back again..
     
    I had a look on the issue now, and here are my findings:
     
    (1) MSC 's usage of our CTI interface seems to be lacking a (necessary) call to ctiGetOperatingConditions(). This call however is included in good old Joy STI interface. So my advice: use the STI interface for your pressure drop simulation, until the Adams glue code to CTI is fixed by MSC. To do so, set the respective environmental variable: MSC_ADAMS_USE_CTI=NO
     
    (2) there is a small typo in FTire's docu chapter on operating condition specification. The line with (TIME_TABLE_INFLATION_PRESSURE_WHEEL_1) must start in column 1. So, this snippet of a tir-file will do the trick:
    (3) as of our next release 2019-2 (to come in 3..4 weeks), there is a completely new and much more powerful mechanism of defining operating conditions and more, in terms of so-called cti-files. Stay tuned for more to come.
     
    Michael
  • 0
    sorry, the snippet was removed in the previous post. Here it is:
    Attached Files (1)
  • 0
    Thank you for your answers Micha and Martin.
     
    I decided to continu with Pac2002 model and check artical KB8016467.
     
    It is coplicated to add these scaling variables to adm file manually.
     
    Is it possible to add these scaling variables to adm file automatically from Acar interface?
     
    Regards,
     
    Yahya​
© 2025 Hexagon AB and/or its subsidiaries. Privacy Policy | Cloud Services Agreement