[Ipopt] Problem with SIMP

[monica marongiu]

Hello,

I do topological optimization on a 3D problem

using the SIMP method whit p=4.


I want a merely 0.001 (black) and 1 (white) design,

but it doesn't happen.



I report output:

----------

IPOPT Note : No hessian given ==> LBFGS hessian approximation enabled
This is Ipopt version 3.10.2, running with linear solver mumps.

Number of nonzeros in equality constraint Jacobian...:        0
Number of nonzeros in inequality constraint Jacobian.:    13202
Number of nonzeros in Lagrangian Hessian.............:        0

Total number of variables............................:    13202
                     variables with only lower bounds:        0
                variables with lower and upper bounds:    13202
                     variables with only upper bounds:        0
Total number of equality constraints.................:        0
Total number of inequality constraints...............:        1
        inequality constraints with only lower bounds:        0
   inequality constraints with lower and upper bounds:        1
        inequality constraints with only upper bounds:        0

  -- FESpace: Nb of Nodes 13202 Nb of DoF 39606
  -- Solve :
          min -0.064877  max 0.093047
iter    objective    inf_pr   inf_du lg(mu)  ||d||  lg(rg) alpha_du alpha_pr  ls
   0  1.1217395e+04 0.00e+00 8.89e+01   0.0 0.00e+00    -  0.00e+00 0.00e+00   0
  -- Solve :
          min -0.0660702  max 0.0942643
   1  1.1708250e+04 0.00e+00 1.40e+02  -0.3 5.25e+01    -  1.00e+00 1.19e-01f  1
  -- Solve :
          min -0.0649783  max 0.0931706



... and so on


 299  8.5618728e+03 0.00e+00 1.63e+01  -0.9 3.08e-02    -  8.76e-01 4.78e-01f  2
  -- Solve :
          min -0.0491874  max 0.066941
  -- Solve :
          min -0.0491929  max 0.0669537
iter    objective    inf_pr   inf_du lg(mu)  ||d||  lg(rg) alpha_du alpha_pr  ls
 300  8.5570186e+03 0.00e+00 2.06e+01  -0.9 3.96e-02    -  1.00e+00 4.13e-01f  2

Number of Iterations....: 300

                                   (scaled)                 (unscaled)
Objective...............:   2.7318990891333351e+03    8.5570186106938800e+03
Dual infeasibility......:   2.0563058857838509e+01    6.4408849521282519e+01
Constraint violation....:   0.0000000000000000e+00    0.0000000000000000e+00
Complementarity.........:   1.4337684852579810e-01    4.4909358696960705e-01
Overall NLP error.......:   2.0563058857838509e+01    6.4408849521282519e+01


Number of objective function evaluations             = 557
Number of objective gradient evaluations             = 301
Number of equality constraint evaluations            = 0
Number of inequality constraint evaluations          = 558
Number of equality constraint Jacobian evaluations   = 0
Number of inequality constraint Jacobian evaluations = 301
Number of Lagrangian Hessian evaluations             = 0
Total CPU secs in IPOPT (w/o function evaluations)   =     62.984
Total CPU secs in NLP function evaluations           =  31406.348

EXIT: Maximum Number of Iterations Exceeded.


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


I don't understand why (at the end) there are parts of for example 0.2 density; I want black or white, not grey. ( I have used the reference toll (10^-8) and I think that the problem is not the "Maximum Number of Iterations Exceeded" )


Thank you


Monica
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