Sensor definition

SENSOR_DEFINITION {
@SENSOR_NAME {SensorName} {
@OBJECT_NAME {ObjectName}
@SENSOR_TYPE {SensorType}
@FRAME_NAME {FrameName}
@ETA_COORDINATE {u, v}
@ROTATION_REPRESENTATION {RotationRep}
@EIGENMODE_NUMBER {Neig}
@SECTION_BUILDER_RECOVERY_NAME {SbRecName}
@COMMENTS {CommentText}
}
}

NOTES

  1. Sensors allow the evaluation of the time histories of various quantities relating to specific elements of the model. Typically, these various quantities are evaluated after the entire simulation is completed and the results are plotted to illustrate the simulation. Sensors are also used in conjunction with controllers, in which case the quantities are computed at each time step of the simulation and are used by the controller directly. Plots of the sensor outputs will be generated, if requested by the plotting control parameters. The plots associated with a sensor are two-dimensional graphs: time is plotted along the x-axis and one or more of the quantities evaluated by the sensor are plotted along the y-axis.
  2. Sensors can be processed at different phases of the analysis.
  3. The quantities to be evaluated by the sensor are defined by four input parameters.
    • The ObjectName indicates the object to be sensed.
    • The SensorType determines the nature of the quantity to be evaluated by the sensor.
    • The FrameName specifies the frame in which the quantity is measured.
    • The quantities u and v specify the location of the sensor within the object.
  4. Sensors can be defined for the following object types.
  5. The SensorType determines the nature of the quantities to be evaluated. Refer to the specific object to find the list of supported SensorType.
  6. The FrameName specifies the frame in which the quantities are measured. Refer to the specific object to find the list of supported FrameName. The following FrameName can be specified.
    • INERTIAL: the quantities are measured in the inertial frame.
    • LOCAL: the quantities are measured in a local frame of reference. Note that this option is not valid for all SensorType.
    • FrameName: the quantities will be measured in a previously defined frame FrameName that can be either a fixed frame, or a moving frame.
  7. The values u and v specify the location where quantities will be evaluated within an element. For single dimensional elements such as beams or cables, a single parameter, u, must be defined, whereas for two-dimensional elements such as membrane or shells, two parameters, u and v, must be defined. Refer to the specific object type find the meaning of these two quantities.
  8. If the output of the sensor involves rotations at a point, the parameter RotationRep can be used to select a specific way to represent rotations.
  9. If the sensor requests quantities pertaining to a specific eigenmode of the system, the eigenmode number, Neig, must be specified.
  10. It is possible to obtain information about local stresses, strains, and warping displacements at any point over the cross-section of beam elements. To access this information, SectionBuilder recovery data, SbRecName, must be defined. To use this option, the sensor definition must satisfy the following requirements.
    • The object name, ObjectName, must refer to a beam element,
    • The sensor type must be either of the following three choices: SensorType = SB_STRAINS, SB_STRESSES, or SB_WARPING. The meaning of these three options is detailed in the list of sensor types.
    • The sensor type must match the RecoveryType defined in the SectionBuilder recovery data, i.e., RecoveryType = SensorType = SB_STRAINS, or RecoveryType = SensorType = SB_STRESSES, or RecoveryType = SensorType = SB_WARPING.
    • No FrameName can be specified.
  11. It is possible to attach comments to the definition of the object; these comments have no effect on its definition.