User Interface

Parameters Used and Positioning in *.par File

The commands are placed in the DVCON_SIZING block as shown below:

  
DVCON_SIZING
    ID_NAME          = MY_EXAMPLE
    EL_GROUP         = ALL_ELEMENTS
    CHECK_TYPE       = DISCRETE
    DISCR_LIST_FILE  = MY_FILE.csv
    DISCR_CYCLE      = 9
    DISCR_INTERVAL   = 3
    DISCR_FRACTION   = 0.1
    DISCR_CHANGE     = 1
 END_

All the required commands are explained in the following table:

COMMAND		DEFAULT VALUE	DESCRIPTION
ID_NAME	=	MY_EXAMPLE'	Id name of the discrete Block. This is a mandatory parameter to be called in OPTIMIZE block
CHECK_TYPE	=	DISCRETE	Check type to be defined. This is a mandatory parameter that activates the discrete method.
DISCR_CYCLE	=	10	Initial cycles to be allowed before constraining. Optional, set enough cycles to achieve partial convergence. (9-15 is a good choice.)
DISCR_INTERVAL	=	4	Cycles between the fixing of DVs. Optional, set enough cycles to allow the solution to converge again. (3-10 is a good choice.)
DISCR_FRACTION	=	0.2	Maximum fraction of the DVs to be fixed in one iteration. Optional, can be set in range 0-1. (0.1-0.3 is a good choice.)
DISCR_CHANGE	=	1	The maximum allowed change in the individual DVs over two iterations. Only DVs with changes below that value will be fixed. Optional parameter. For accurate results small values (0.001,0.1) should be used, however the number of required cycles cannot be estimated in advance. To deactivate this feature for guaranteed termination of algorithm very large values (~10) should be used.
DISCR_LIST_FILE	=	MY_FILE.csv	Name of the file containing the discrete range. This is a mandatory parameter. Only one file is allowed inside the DISCRETE block. This file should contain only one labeled column with arbitrary length.

The file containing the discrete thickness values should looks like the following one:

MY_THICKNESSES
0.111
0.25
...
2.0

The thickness values given in the file should be written in decimal form. A period should be used to separate the integer part from the fractional part also in cases where the fractional part is zero.

Note that upper and lower bounds of design variables will be added to this list by the system. In cases where such bounds are not specified by the user, plus and minus 20 percent of the current design variable values will be used as bounds.

Efficient Usage of the Discrete Sizing Feature

To use the discrete sizing feature efficiently, the following additional settings can be added:

• A DVCON_SIZING block explicitly specifying the thickness bounds should be created.
• STOP_CRITERION_ITER parameter should be included in the OPT_PARAM block and set to a required value. (For ex. With the default parameter set, it should be set to 28, that is, expected number of iterations +1).
• The list values for discrete sizing must be in a mechanically sensible range, and not too different from the thickness values of the initial design.