ADAMS/CAR unknown error 3

[PeteTranc]

Just recently I have started using Adams/CAR for double wishbone suspension kinematic and element force analysis. Before I used to build my wire frame rigid models using Adams/View which worked great as far as the simulation is concerned but it lacked the prebuild functions for example setting/measurement of Camber, Toe etc. that Adams/Car is specialized for. I have went thru most of Adams/CAR tutorials dealing mostly with template usage, which should be fine for my case. This was my workflow for front suspension analysis:
1. created a new assembly with TR_front_suspension.sub as the only subsystem (i will include steering subsystems later, for now only bump-rebound characteristics)
2. modified hard points to suite my design. My coordinate system is in the intersection of ground plane/fvsa plane/longitudinal symmetry plane. x-axis is pointing forward y-axis to the left which is opposite in Adams so i just changed the sign in these two directions. Also I set every coordinate of testrig to 0 I
3. I modified coil over properties to linear spring (i have only theoretical spring calculations) and some minimal damping (at this point i am not concerned with velocity-damping response)
4. Edited tire data (unloaded radius and tire stiffness) and vehicle parameters.
5. Suspension analysis: parallel travel 80mm bump -60mm rebound

With default solver settings I got this message:
=================================================================
Adams/Tire
Version Adams 2013.2
=================================================================

acar_2013.1.0/ac_scc_init

Reading ARRAY parameters using the
ADAMS/Car array statement definitions.

acar_2013.1.0/ac_scc_init

Checking ARRAY parameters...

-------------------------------------------------------------------------------
| Model Title |
|=============================================================================|
| |
| Adams/Car Assembly (Adams 2013.2) |
| |
-------------------------------------------------------------------------------

command: preferences/solver=CXX
command: preferences/list,status=on
PREFERENCES:
SIMFAIL = NOSTOPCF
Contact Geometry Library = Default
Contact Faceting Tolerance = 1
Thread Count = 1
Library Search Path = Not Set
Status Message = On
Solverbias = CXX (C++ Solver)

command: control/ routine=acarSDM::con950, function=user(950,29,31,1,2,18,20,1,3,2,3,28,30,2,3,28,30,1,1)


Begin Static Solution


STATICS: Original static solver will be used with the Sparse linear solver.


---- START: WARNING ----
Actuator reached upper force limit

---- END: WARNING ----


---- START: ERROR ----

Static equilibrium analysis has not been successful.
The maximum number of iterations 25, has been reached.
For the last attempted iteration:
The equation with the largest error was model.TR_Front_Suspension.ges_subframe Comp = 8 Error = 200849082.519939
The variable receiving the largest increment was model.testrig.jolfix_table_fixed Comp = 4 Delta = 161973045.741471.

---- END: ERROR ----
Static Solution failed to converge

End Static Solution

Simulation failed



---- START: ERROR ----
Initial Static Sim. Not Successful
ID = 0


---- END: ERROR ----


---- START: ERROR ----

Adams/Solver run terminating due to STOP requested by user.


---- END: ERROR ----

Termination status=-995

Terminating Adams/Car usersubs...


Finished -----
Elapsed time = 0.31s, CPU time = 0.30s, 96.08%
Analysis failed!
Please check the error messages to determine the cause.
-----------------------------------------------------------------------------------------------------------------------------------------------------------

Then I increased the MaxIt for static solver from 25 to 50. It convergences to a result but it's nonsense (see attached 1.jpeg) This is the lower part of the message:

------------------------------------------------------------------------------------------------------------------------------------------------------------
****** Performing Quasi-Static Simulation ******

---- START: WARNING ----

The Reconcile Acceleration-Force has detected a singular Jacobian matrix.
This problem may be caused by:
(a) A constraint equations that became almost redundant, e.g., the model
is at a singular configuration or at a bifurcation point.
(b) A massless PARTS in the model.

The Sparse Solver has detected a zero pivot for row 67 (during the symbolic pivot selection).
The corresponding equation is: Part/26 X Force

A minimization algorithm will be used to find a solution on the
projected constraint manifold.

---- END: WARNING ----
Simulation Step Function Cumulative CPU
Time Size Evaluations Steps Taken time
___________ ___________ ___________ ___________ ________
1.00000E+00 0.00000E+00 0 0 0.70
2.00000E+00 1.00000E+00 116 13 0.75
3.00000E+00 1.00000E+00 124 14 0.80
4.00000E+00 1.00000E+00 132 15 0.83
5.00000E+00 1.00000E+00 140 16 0.88
6.00000E+00 1.00000E+00 148 17 0.94
7.00000E+00 1.00000E+00 156 18 0.98
8.00000E+00 1.00000E+00 165 19 1.02
9.00000E+00 1.00000E+00 174 20 1.08

---- START: WARNING ----
Actuator reached upper force limit

---- END: WARNING ----
1.00000E+01 1.00000E+00 209 21 1.22
1.10000E+01 1.00000E+00 228 22 1.30

End Simulation

Simulate status=0

command: !
command: stop

Termination status=0

Terminating Adams/Car usersubs...


Finished -----
Elapsed time = 1.30s, CPU time = 1.30s, 100.07%
Simulation(s) are complete!
Loading analysis results...
Removing analyses of the same name from session...
Loading results done.


--------------------------------------------------------------------------------


Do you know what is wrong with my input data. Any help is much appreciated.

Attachments:

http://files.engineering.com/getfile.aspx?folder=983a9b49-c5dc-4e82-92cc-38302481b81d&file=1.JPG

http://files.engineering.com/getfile.aspx?folder=991fcc37-4a17-477d-81ac-05814df7f6eb&file=2.JPG

http://files.engineering.com/getfil...784d-459b-84ad-851cf7c18922&file=HP_table.JPG

 

[GregLocock]

send your files to msc, they are cheaper than me.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[PeteTranc]

GregLocock, thank you for the suggestion. I will check if our license includes MSC support. We are using educational licenses, which were hard to acquire in the first place, so I hope for the best... Meanwhile, if someone sees what went wrong, please comment.

 

[GregLocock]

Otherwise, start from the supplied configuration, which hopefully works. Do your test with that. Then change each parameter to your new value and rerun until you find which mod is breaking the model.



Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[PeteTranc]

I remember doing that in the past and each time it failed after I set the first HardPoint, any HardPoint. My problem regarding the ''Actuator reached upper force limit'' at the start of this tread was resolved by adjusting the spring preload, more precisely lowering it. After that, Adams successfully converged using default solver settings. That's one problem solved. I still get the result where the tie-rod ''breaks'' and the actuator penetrates the tire as seen in one of the attachments above.