RESPONSE VARIABLE
Specifies the responses to be used for optimization.
Type
AcuSolve Command
Syntax
RESPONSE_VARIABLE {parameters}
Qualifier
This command has no qualifier.
Parameters
 type (enumerated) [=surface_output]
 Responsible variable types.
 surface_output
 element_output
 time_history_output
 time_history_output_distance or dist
 topology_variable
 design_variable
 constant or const
 identity or id
 square or sq
 cube
 square_root or sqrt
 exponential_function or exp
 natural_logarithm or ln
 sine or sin
 cosine or cos
 tangent or tan
 cotangent or cot
 arcsine or asin
 arccosine or acos
 arctangent or atan
 arccotangent or acot
 negation or neg
 reciprocal or one_over
 absolute or abs
 ratio or over
 addition or plus
 subtraction or minus
 multiplication or times
 power or pow
 average or mean
 average_absolute_value
 minimum or min
 minimum_absolute_value
 absolute_minimum_value
 maximum or max
 maximum_absolute_value
 absolute_maxmimum_value
 summation or sum
 sum_absolute_value
 sum_squares
 sqrt_sum_squares or norm
 weighted_sum
 product
 surface_output (string) [=""]
 User defined name of the surface from which the output will be extracted.
 surface_output_variable (enumerated) [=pressure]
 The surface output variables are used in the
RESPONSE_VARIABLE command.
 x_traction
 y_traction
 z_traction
 mass_flux
 heat_flux
 x_velocity or xvel
 y_velocity or yvel
 z_velocity or zvel
 temperature or temp
 pressure or pres
 area
 partial_volume
 element_output (string) [=""]
 User defined name of the element set from which the output will be extracted.
 element_output_variable (enumerated) [=volume]
 Element output quantities are used in optimization.
 volume
 x_velocity or xvel
 y_velocity or yvel
 z_velocity or zvel
 pressure or pres
 temperature or temp
 total_pressure
 mass
 time_history_output (string) [="unknown"]
 User defined name of time history output.
 time_history_output_variable (enumerated) [=pressure]
 Time history output quantities are used in optimization.
 x_undeformed or x0
 y_undeformed or y0
 z_undeformed or z0
 x_deformed or x
 y_deformed or y
 z_deformed or z
 x_velocity or xvel
 y_velocity or yvel
 z_velocity or zvel
 pressure or pres
 temperature or temp
 time_history_output_1 (string) [=" "]
 User defined name of time history output point. Used with time_history_output_distance.
 time_history_output_2 (string) [=""]
 User defined name of time history output point. Used with time_history_output_distance.
 time_history_output_coordinates_1 (enumerated) [=deformed]
 Specifies the method of tracking time_history_output_1
location.
 undeformed_coordinates or undeformed
 deformed_coordinates or deformed
 time_history_output_coordinates_2 (enumerated) [=deformed]
 Specifies the method of tracking time_history_output_2
location.
 undeformed_coordinates or undeformed
 deformed_coordinates or deformed
 time_history_index_1 (integer) [=1]
 Time history indices must be referenced by the order of the coordinates in the time history output command.
 time_history_index_2 (integer) [=1]
 Time history indices must be referenced by the order of the coordinates in the time history output command.
 design_variable (string) [=""]
 User defined name of the design variable.
 topology_variable (enumerated) [=mechanical_energy]

 mechanical_energy
 Mechanical energy.
 design_volume_fraction
 The integral of the design variables field variable divided by the volume of the design space. This will give a value of zero for an empty design space, and a value of one for a design space where the design variables field variable is constant one.
 constant_response (real) [=0.0]
 Specifies a constant value.
 response_variables (list) [={}]
 Specifies the response variables.
 weights (array) [={}]
 Specifies the factors multiplying the response variables in a weighted sum. If you use M response variables in the weighted sum, you need to specify M weights.
Description
The objectives and constraints are defined in terms of response variables that may reference surface or volume outputs. Response variables may also control parameters by using multiplier functions of type set to response_variable. The values of the objective and constraint functions are computed using response variable commands. In turn, the values of the response variable functions are computed from either (i) integrated surface quantities, (ii) integrated volume quantities, (iii) design variables, (iv) given constants, or (v) functions of one or more other response variables.
Below are some examples of responses.
RESPONSE_VARIABLE(“inflow pressure”) {
type = surface_output
surface_output = “inflow”
surface_output_variable = pressure
}
SURFACE_OUTPUT(“inflow”) {
surfaces = Read( “inflow.srf” )
shape = three_node_triangle
element_set = “fluid”
integrated_output_frequency = 1
}
RESPONSE_VARIABLE(“mass of object”) {
type = element_output
element_output = “object”
element_output_variable = mass
}
ELEMENT_OUTPUT(“object”) {
elements = Read( “object.cnn” )
shape = four_node_tet
element_set = “object”
integrated_output_frequency = 1
}
RESPONSE_VARIABLE(“temperature in a node”) {
type = time_history_output
time_history_output = “oth_node”
time_history_output_variable = temperature
}
TIME_HISTORY_OUTPUT(“oth_node”) {
type = nodal
nodes = { 54 }
output_frequency = 1
}
RESPONSE_VARIABLE(“xposition of a deformed point”) {
type = time_history_output
time_history_output = “oth_point”
time_history_output_variable = x_deformed
}
TIME_HISTORY_OUTPUT(“oth_point”) {
type = coordinates
coordinates = { 1, 1,0, 0.0, 2.0 }
output_frequency = 1
}
RESPONSE_VARIABLE(“distance between two deformed points”) {
type = time_history_output
time_history_output_1 = “points”
time_history_output_2 = “points”
time_history_output_coordinates_1 = deformed
time_history_output_coordinates_2 = deformed
time_history_index_1 = “1”
time_history_index_2 = “2”
}
TIME_HISTORY_OUTPUT(“oth_point”) {
type = coordinates
coordinates = {
1, 0.0, 0.0, 0.0
2, 2.0, 3.0, 0.0
}
output_frequency = 1
}
Note that the indices in time history output are numbered from one to two and are referenced in the response variable command. In general, the response variable command time history indices must be referenced by the order of the coordinates in the time history output command. The first column is not the index number, but the point identifier.
RESPONSE_VARIABLE(“mechanical energy”) {
type = topology_variable
topology_variable = mechanical_energy
}