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Hello,

 

I am trying to run the Optistruct Tutorial OS 2098 with the MBD excavator arm. 

The analysis works fine, but optimization unfortunately not. Doing everything like in the tutorial, I get errors you can see in the attached output file.

 

Decreasing h_min in the Load_Collector doesn't help. Like it is recommended in line 1062 in the output. But if i decrease h_min to 1e-14, Iteration 0 is running for hours now. So this could not be the right way to solve the tutorial i guess. 

Is this the only big error? Or are there others I can solve?

 

Would be great to get this tutorial running, because my goal in optistruct is to optimize one part in a MBD, too. 

 

Thanks in Advance!

 

os_2098_error.txt

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Hi,

 

Can you paste the entire error message here?

I am unable to open the .out file on my phone

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Hi,

 

here are all parts where i can find "error".

I also change the document type in my first post to a .txt file.

 ...

Time=1.000E+00; Order=1; H=6.568E-13 [Max Phi=1.978E-11]
 Time=1.000E+00; Order=1; H=1.984E-12 [Max Phi=2.583E-11]
 Time=1.000E+00; Order=1; H=7.583E-13 [Max Phi=3.173E-11]
 Time=1.000E+00; Order=1; H=9.607E-13 [Max Phi=3.801E-11]

WARNING: Simulation terminated because stepsize has diminished consistently belo

ERROR: At time=1.000E+00 the integrator failed to proceed.

----------- Possible Causes ----------------------------------------------------
(1) The integration has become unstable. Tighten (decrease) integr_tol, h_max,
or both in Param_Transient can help stabilize the integration. If the simulation
contains distinctive phases, use multiple Simulate, each with its
own proper integrator parameter setting, to selectively tighten the tolerance
during the period where instability is encountered.
(2) If the simulation was terminated because stepsize has diminished consistentl
below h_min, reduce h_min in Param_Transient to force integration to continue.
(3) Non-physical inertia properties, such as mass=100 Kg and Ixx=Iyy=Izz=1 Kg*mm
or extremely small inertia on a part with an unconstrained degree of freedom.
Make sure the modeling data, in particular the part inertia and the gravity, are
specified in proper units consistent with the units given in Param_Unit element.
(4) Beam, flexible body goes out of linear range, bushing has large rotation alo
more than one axis, curve goes out of its interpolation range, higher-pair joint
goes out of the range of U or V, etc. Make sure fundamental modeling assumptions
such as rigid contact assumption used in Force_Contact, are not violated.
(5) Motion displacement defined using LINSPL, AKISPL in dynamic analysis, or as
function of model states (DX, VX etc), as well as forces defined as a function o
other forces, can cause hard convergence and integrator failure. Avoid these
modeling practices wherever possible.
--------------------------------------------------------------------------------

 

....

ERROR: Error encountered in analysis!


Forced termination from API_SendOffCommandSimulate!
Error: MBD analysis failed.
 
 This error occurs in module "mbddrv".

************************************************************************
 FEASIBLE DESIGN (ALL CONSTRAINTS SATISFIED).
  
 Delete bootstrap file xxx/excavator_MBD_Topology.OS_dumpfile_scr.bin

************************************************************************

...

 *** PROGRAM STOPPED: FATAL ERROR(s) ENCOUNTERED.

                        ***** END OF REPORT *****
 
 For Useful OptiStruct Tips and Tricks, go to the URL:
http://www.altairhyperworks.com/tips.aspx
 
************************************************************************
  
 A fatal error has been detected during input processing:
  FEASIBLE DESIGN (ALL CONSTRAINTS SATISFIED).
  
  
 
************************************************************************

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On 13.5.2016 at 7:02 AM, Prakash Pagadala said:

Hi,

 

Can you paste the entire error message here?

I am unable to open the .out file on my phone

Hi,

 

I upload the file as pdf. But if you really prefer all of the 1200 lines in here. I can do this =)

 

Thanks

 

Regards

 

os_2098_error.pdf

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