Design Variable dialog box

Modeling Object
Name	Sets a unique name for the design variable.
Label	Sets a unique integer for the modeling object.The dialog box automatically displays the next available modeling object number. However, you might want to change this if you use a particular series of numbers to identify certain types of modeling objects.
Properties
Description	Sets a description for the design variable.You can also click Description to open the Description dialog box. This lets you see more of the text that you type, as well as cut, copy, or paste text.This description appears only on this dialog box.
Card Name	Displays the names of the Nastran bulk entries that will be generated when you solve the solution: DESVAR, DVPREL1, DVMREL1, and DVCREL1.The card names that appear in this box vary, depending on the type of design variable you are creating or editing.
Design Variable (DESVAR)
The value for Relation Definition in the Property Relation (DVPREL1), Material Relation (DVMREL1), or Connectivity Relation (DVCREL1) group affects how Initial Value, Lower Bound, and Upper Bound are handled:If Relation Definition is set to User Defined, those options are handled as actual values.Be sure to consider the unit of measurement for the model. For example, if the response is for displacement, and your model's units are metric, the unit is mm.If Relation Definition is set to Assigned at Export, those options are handled as scale factors.Note: For a SOL 200 Design Sensitivity Analysis solution, any values for Initial Value, Lower Bound, Upper Bound, and Fractional Change are ignored by the Nastran solver.
Label	Sets the design response identifier to write to the .f06 file when you solve the solution.This label must begin with an alphabetic character.
Initial Value	Sets the starting value of the attribute to vary.For example, if you are varying the membrane thickness, and the modeled thickness of the shell elements is 0.2 mm, type0.2. If you are specifying a scale factor, type the initial scale factor, such as 1.0.Note: If this design variable is for use with a SOL 200 Model Update solution, always specify a scale factor.
Lower Bound	Sets the lowest value (or scale factor) that the solver can use when varying this property.
Upper Bound	Sets the highest value (or scale factor) that the solver can use when varying this property.
Fractional Change	Sets the fractional change allowed for the design variable during approximate optimization.If you do not specify a value, the default value is 1.0.
Property Relation (DVPREL1)
Appears when you create or edit a property or composite property design variable.
Type	Specifies the type of physical property to allow the solver to vary.
Physical Property	Specifies the physical property table that contains the property to vary.In None is selected in the list, you can create a new physical property table. To do this, click Create Physical and complete the displayed dialog box.To modify a selected physical property table that is not locked, click Edit .You can also click Open Manager to create a new physical property table by copying an existing one.To search for a physical property table, click More Options . For more information, see Filter options.Note: The selected physical property must be referenced by a mesh collector.
Property Field	Specifies the property to vary (for example, the T field in a PSHELL).
Minimum Value Allowed	Appears when you create or edit a composite property design variable.Sets the minimum value allowed for this property.This value must be explicitly set to a negative number for properties that might be less than zero.In addition, the Minimum Value Allowed and Maximum Value Allowed values might be violated at a given design cycle if another, more critical violation by response constraints occurs. Because design variables may never violate their lower and upper limits, try to configure the property values so that they are not violated even for infeasible designs (if possible and reasonable).
Maximum Value Allowed	Appears when you create or edit a composite property design variable.Sets the maximum value allowed for this property.
Relation Definition	Specifies how the solver uses the values for Initial Value, Lower Bound, and Upper Bound.Assigned at ExportHandles the initial value and lower/upper bounds as scale factors.When you solve and the solver input file is exported, the solver uses the following variable relation equation:Pi = COEF * DVIDWhere:Pi is the actual variable range used by the solution.COEF is an automatically assigned coefficient based on the current property value.DVID is the range defined by the initial, lower, and upper scale values.For example, if the current value of a shell thickness variable is 0.2, a COEF value of 0.2 is assigned during the solution export process, and the initial, lower, and upper values are applied as scale factors. If Initial Value is set to 1.0, Lower Bound is set to 0.5, and Upper Bound is set to 2.0, then the actual variable range used by the solution is 0.1 (0.2 * 0.5) to 0.4 (0.2 * 2.0).User DefinedHandles the initial value and lower/upper bounds as actual values.When you solve and the solver input file is exported, the solver uses the following variable relation equation:Pi = C0 + COEF * DVIDWhere:Pi is the actual variable range used by the solution.C0 is a constant term that you specify.COEF is a coefficient that you specify.DVID is the range defined by the initial, lower, and upper scale values.You can use C0 (Constant Term) and COEF (Coefficient) to scale the variable range linearly.If you set Constant Term to 0.0 and Coefficient to 1.0, the equation becomes Pi = DVID, and the initial, lower, and upper values are applied relative to the actual variable range.For example, if Constant Term is set to 0.0, Coefficient is set to 1.0, Initial Value is set to 0.2, Lower Bound is set to 0.1, and Upper Bound is set to 0.4, then the actual variable range used by the solution is 0.1 to 0.4 mm.
Constant Term	Appears when Relation Definition is set to User Defined.Sets the constant term (C0) to use in the solver's variable relation equation.In most cases, you can use the default value of 0.
Coefficient	Appears when Relation Definition is set to User Defined.Sets the coefficient (COEF) to use in the solver's variable relation equation.In most cases, you can omit a value, which sets the coefficient to 1.
Material Relation (DVMREL1)
Appears when you create or edit a material design variable.
Material	Specifies the material that contains the material property to vary.To select a different material, click Choose Material and select the material in the Material List dialog box.Note: The selected material must be referenced by a mesh collector.
Type	Appears when a material is selected.Specifies the name of a material property bulk entry, such as MAT1.
Material Field	Specifies the material property to vary (such as E, RHO, and so on).
Relation Definition	Specifies how the solver uses the values for Initial Value, Lower Bound, and Upper Bound.For more information, see the description of Relation Definition in the Property Relation (DVPREL1) group.
Connectivity Relation (DVCREL1)
Appears when you create or edit a connectivity design variable.
Group	Specifies the group that contains the elements to modify using this design variable.To create a new group, click New Group and complete the New Group dialog box.To search for a group, click More Options . For more information, see Filter options.
Type	Specifies the type of elements to modify, such as CBAR.
Element Field	Specifies the field to modify.For example, you can modify the X1 field of the CBAR elements in the group you selected.
Relation Definition	Specifies how the solver uses the values for Initial Value, Lower Bound, and Upper Bound.For more information, see the description of Relation Definition in the Property Relation (DVPREL1) group.

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Create a design variable for a design sensitivity analysis

Create a design variable for design optimization

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Design Variable dialog box, Simcenter 3D 2021.1 Series

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