Update Strategy of the Method of Moving Asymptotes

The shell thicknesses of the structure are updated using the method of moving asymptotes (MMA), see Svanberg (1987). Normally, the update method suggested in Svanberg (1987) is stable. However, if the design responses are very sensitive, it is suggested to use a more conservative update method that requires more optimization iterations.

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OPT_PARAM

The update strategy is changed using the parameter THICKNESS_UPDATE. The default value of THICKNESS_UPDATE is NORMAL. Setting THICKNESS_UPDATE to CONSERVATIVE leads to a conservative update of the design variables:

OPT_PARAM
  ID_NAME = opt_params
  OPTIMIZE = id_of_optimize
  THICKNESS_UPDATE = CONSERVATIVE
END_
Important:

It is recommended to use the conservative update method if it is problematic to fulfill the constraints used in the optimization formulation.

The user also has the possibility to use a more aggressive update of the design variables in order to reduce the number of optimization iterations by setting THICKNESS_UPDATE to AGGRESSIVE:

OPT_PARAM
  ID_NAME = opt_params
  OPTIMIZE = id_of_optimize
 THICKNESS_UPDATE = AGGRESSIVE
END_
Warning:

This may lead to unstable optimization or prevent the convergence.