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Buckling Analyse with INREL-2 and MATS1

User: "Altair Forum User"
Altair Employee
Updated by Altair Forum User

Hello,

 

i have a Problem with a buckling Analyse:

 

There is a Aluminium Piece with three bores. In each bare there is a RBE3 with Loads and moments in every direction (xyz). The model is fixed by PARAM AutoSPC=YES and INREL=-2. The question is: How much plastic Deformation will be left after the load is being applied and than  decreased to 0...

 

I tried it with two Non-Linear quasi-static loadsteps and MATS1 Material as a table.

 

The Analysis is runing until 50-60% of the load is reached and than gives this error:

 

*** ERROR # 4965 ***
 Maximum number of time increment cutbacks reached,
 analysis aborted.

 

It appears because 5 approaches to correct the foregone load increment. It seems, that the plastic Deformation starts at that Point and it expands extremly fast:

 

 Starting load increment 88 Current increment 9.8192E-008

  Subcase         6  Load step:  5.5889E-01
--------------------------------------------------------------------------------
               Nonlinear Error Measures  Gap and Contact Element Status  Maximum
 Iter Avg. U    EUI      EPI      EWI    Open Closed Stick Slip Frozen  Plststrn
--------------------------------------------------------------------------------
  1  5.97E-03 1.00E-03 2.31E-05 3.12E-08     0     0     0     0     0  5.93E-02
  2  2.80E-03 1.46E+00 2.85E-01 8.33E-01     0     0     0     0     0  3.91E-02
  3  3.85E-03 3.40E-01 1.19E-01 7.60E-02     0     0     0     0     0  9.51E-02
  4  7.48E-03 1.24E+00 5.51E+00 6.39E+00     0     0     0     0     0  2.22E+00
  5  1.34E-02 7.32E-01 5.55E+02 5.23E+02     0     0     0     0     0  7.95E+00
 
 
 Adjusting load increment 88 (correction #1), Current increment 2.4548E-008

  Subcase         6  Load step:  5.5889E-01
--------------------------------------------------------------------------------
               Nonlinear Error Measures  Gap and Contact Element Status  Maximum
 Iter Avg. U    EUI      EPI      EWI    Open Closed Stick Slip Frozen  Plststrn
--------------------------------------------------------------------------------
  1  5.97E-03 1.00E-03 2.31E-05 3.12E-08     0     0     0     0     0  5.93E-02
  2  2.80E-03 1.46E+00 2.85E-01 8.33E-01     0     0     0     0     0  3.91E-02
  3  3.85E-03 3.40E-01 1.19E-01 7.60E-02     0     0     0     0     0  9.51E-02
  4  7.49E-03 1.24E+00 5.51E+00 6.39E+00     0     0     0     0     0  2.23E+00
  5  9.59E-03 7.22E-01 1.96E+03 1.27E+03     0     0     0     0     0  8.26E+00
 
 
 Adjusting load increment 88 (correction #2), Current increment 6.1370E-009

  Subcase         6  Load step:  5.5889E-01
--------------------------------------------------------------------------------
               Nonlinear Error Measures  Gap and Contact Element Status  Maximum
 Iter Avg. U    EUI      EPI      EWI    Open Closed Stick Slip Frozen  Plststrn
--------------------------------------------------------------------------------
  1  5.97E-03 1.00E-03 2.31E-05 3.12E-08     0     0     0     0     0  5.93E-02
  2  2.80E-03 1.46E+00 2.85E-01 8.33E-01     0     0     0     0     0  3.91E-02
  3  3.85E-03 3.40E-01 1.19E-01 7.60E-02     0     0     0     0     0  9.51E-02
  4  7.49E-03 1.23E+00 5.51E+00 6.38E+00     0     0     0     0     0  2.23E+00
  5  9.73E-03 7.17E-01 1.02E+03 7.05E+02     0     0     0     0     0  7.19E+00
 
 
 Adjusting load increment 88 (correction #3), Current increment 1.5343E-009

  Subcase         6  Load step:  5.5889E-01
--------------------------------------------------------------------------------
               Nonlinear Error Measures  Gap and Contact Element Status  Maximum
 Iter Avg. U    EUI      EPI      EWI    Open Closed Stick Slip Frozen  Plststrn
--------------------------------------------------------------------------------
  1  5.97E-03 1.00E-03 2.31E-05 3.12E-08     0     0     0     0     0  5.93E-02
  2  2.80E-03 1.46E+00 2.85E-01 8.33E-01     0     0     0     0     0  3.91E-02
  3  3.85E-03 3.40E-01 1.19E-01 7.60E-02     0     0     0     0     0  9.51E-02
  4  7.49E-03 1.23E+00 5.51E+00 6.38E+00     0     0     0     0     0  2.23E+00
  5  9.78E-03 7.18E-01 2.99E+03 2.15E+03     0     0     0     0     0  8.65E+00
 
 
 Adjusting load increment 88 (correction #4), Current increment 3.8356E-010

  Subcase         6  Load step:  5.5889E-01
--------------------------------------------------------------------------------
               Nonlinear Error Measures  Gap and Contact Element Status  Maximum
 Iter Avg. U    EUI      EPI      EWI    Open Closed Stick Slip Frozen  Plststrn
--------------------------------------------------------------------------------
  1  5.97E-03 1.00E-03 2.31E-05 3.12E-08     0     0     0     0     0  5.93E-02
  2  2.80E-03 1.46E+00 2.85E-01 8.33E-01     0     0     0     0     0  3.91E-02
  3  3.85E-03 3.40E-01 1.19E-01 7.60E-02     0     0     0     0     0  9.51E-02
  4  7.50E-03 1.23E+00 5.51E+00 6.38E+00     0     0     0     0     0  2.23E+00
  5  9.79E-03 7.18E-01 5.96E+02 4.02E+02     0     0     0     0     0  6.46E+00
 
 
 Adjusting load increment 88 (correction #5), Current increment 9.5891E-011

  Subcase         6  Load step:  5.5889E-01
--------------------------------------------------------------------------------
               Nonlinear Error Measures  Gap and Contact Element Status  Maximum
 Iter Avg. U    EUI      EPI      EWI    Open Closed Stick Slip Frozen  Plststrn
--------------------------------------------------------------------------------
  1  5.97E-03 1.00E-03 2.31E-05 3.12E-08     0     0     0     0     0  5.93E-02
  2  2.80E-03 1.46E+00 2.85E-01 8.33E-01     0     0     0     0     0  3.91E-02
  3  3.85E-03 3.40E-01 1.19E-01 7.60E-02     0     0     0     0     0  9.51E-02
  4  7.50E-03 1.23E+00 5.51E+00 6.38E+00     0     0     0     0     0  2.23E+00
  5  9.80E-03 7.18E-01 5.47E+02 4.05E+02     0     0     0     0     0  6.67E+00
 
 *** ERROR # 4965 ***
 Maximum number of time increment cutbacks reached,
 analysis aborted.
 
 Saved the last (NOT-CONVERGED!) iteration for diagnostics.
 
 *** Nonlinear solution failed to converge for Subcase 6 ***

        NONLINEAR  ITERATION  SUMMARY FOR    Subcase        7
        Continuing nonlinear solution from   Subcase        6
        Subcase        6 did not converge - cannot continue.

 
 Saved the last (NOT-CONVERGED!) iteration for diagnostics.

 

Maximum Plastic Strain at 6,67mm in itteration 5, that is way to high...

 

 

Does someone already had this Problem or some advice for this sort of buckling analyse?

 

Thank You and best regards

HyperName

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