FEA DesignVariable

Structure for the design variable tuple = ("DesignVariable Name", "Value"). "DesignVariable Name" defines the reference name for the design variable being specified. This string will be used in the FEA input directly. The "Value" must be a JSON String dictionary (see Section JSON String Dictionary). In Nastran the DesignVariable Name will be the LABEL used in the DESVAR input. For this reason the user should keep the length of this input to a minimum number of characters, ideally 7 or less.

• DESVAR ID LABEL XINIT XLB XUB DELXV DDVAL

JSON String Dictionary

If "Value" is JSON string dictionary (eg. "Value" = {"designVariableType": "Property", "groupName": "plate", "upperBound": 10.0, "fieldName": "TM"}) the following keywords ( = default values) may be used:

• designVariableType = "Property"
  Type of design variable in an optimization problem. Options: "Material", "Property".

• groupName = "(no default)"
  Single or list of capsGroup or FEA Material name(s) to the design variable (e.g. "Name1" or ["Name1","Name2",...].
  • For designVariableType Property a capsGroup Name (or names) is given. The property (see FEA Property) also assigned to the same capsGroup will be automatically related to this design variable entry.
  • For designVariableType Material a FEA Material name (or names) is given.

• initialValue = 0.0
  Initial value for the design variable.

• lowerBound = 0.0
  Lower bound for the design variable.

• upperBound = 0.0
  Upper bound for the design variable.

• maxDelta = 0.0
  Move limit for the design variable.

• discreteValue = 0.0
  List of discrete values do use for the design variable (e.g. [0.0,1.0,1.5,3.0].

• fieldName = "(no default)"
  Fieldname of variable (e.g. "E" for Young's Modulus). Design Variables can be defined as two types based on the designVariableType value. These are Material or Property. This means that an aspect of a material or property input can change in the optimization problem. This input specifies what aspect of the Material or Property is changing.
  1. Material Types Selected based on the material type (see FEA Material, materialType) referenced in the groupName above.
     • MAT1, materialType = "Isotropic"
       • "E", "G", "NU", "RHO", "A"
     • MAT2, materialType = "Anisothotropic"
       • "G11", "G12", "G13", "G22", "G23", "G33", "RHO", "A1", "A2", "A3"
     • MAT8, materialType = "Orthotropic"
       • "E1", "E2", "NU12", "G12", "G1Z", "G2Z", "RHO", "A1", "A2"
     • MAT9, materialType = "Anisotropic"
       • "G11", "G12", "G13", "G14", "G15", "G16"
       • "G22", "G23", "G24", "G25", "G26"
       • "G33", "G34", "G35", "G36"
       • "G44", "G45", "G46"
       • "G55", "G56", "G66"
       • "RHO", "A1", "A2", "A3", "A4", "A5", "A6"
  2. Property Types (see FEA Property)
     • PROD propertyType = "Rod"
       • "A", "J"
     • PBAR propertyType = "Bar"
       • "A", "I1", "I2", "J"
     • PSHELL propertyType = "Shell"
       • "T"
     • PCOMP propertyType = "Composite"
       • "T1", "THETA1", "T2", "THETA2", ... "Ti", "THETAi"
     • PSOLID propertyType = "Solid"
       • not supported

• fieldPosition = 0
  This input is ignored if not defined. The user may use this field instead of the fieldName input defined above to relate design variables and property inputs. This requires knowledge of Nastran bulk data input format for material and property input cards.

• independentVariable = "(no default)"
  Single or list of "DesignVariable Name"s (that is the Tuple name) used to create/designate a dependent design variable.
  • independentValue = variableWeight[1] + variableWeight[2] * SUM{independentVariableWeight[i] * independentVariable[i]}

• independentVariableWeight = 1.0 or [1.0, 1.0, ...]
  Single or list of weighting constants with respect to the variables set for "independentVariable". If the length of this list doesn't match the length of the "independentVariable" list, the list is either truncated [ >length("independentVariable")] or expanded [ <length("independentVariable")] in which case the last weight is repeated.

• variableWeight = [1.0, 1.0]
  Weighting constants for a dependent variable - used if "independentVariable"(s) have been provided.