Update Strategy of the Convex Separable Approximations

The relative material volumes of elements of the structure are updated using the method of Convex Separable Approximations (CSA), see Svanberg (2002).

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OPT_PARAM

Normally, the update method suggested in Svanberg (2002) 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. The update strategy is changed using the parameter DENSITY_UPDATE. The default value of DENSITY_UPDATE is NORMAL. Setting DENSITY_UPDATE to CONSERVATIVE leads to a conservative update of the design variables:


OPT_PARAM
 ID_NAME        = opt_params
 OPTIMIZE       = id_of_optimize
 DENSITY_UPDATE = CONSERVATIVE
END_

Note: The conservative update method is recommended if it is problematic to fulfill the constraints used in the optimization formulation.

In addition, you can use a more aggressive update of the design variables to reduce the number of optimization iterations by setting DENSITY_UPDATE to AGGRESSIVE:


OPT_PARAM
 ID_NAME        = opt_params
 OPTIMIZE       = id_of_optimize
 DENSITY_UPDATE = AGGRESSIVE
END_

Warning: This might lead to unstable optimization or prevent the convergence.