19.5.19. Structural Probes

This section provides:

A general description of structural probe types.
An explanation of the differences for rigid body probes during Explicit Dynamics analyses.

Additional Probe Information

See the Probes section for further information. In addition, see the following sections for details on these probe types:

Structural Probe Types

The following structural probe types are available.

Probe Type	Applicable Analysis Types	Output	Characteristics
Deformation	Coupled Field Static, Coupled Field Transient, Static Structural, Transient Structural, Rigid Dynamics, Explicit Dynamics, LS-DYNA	Deformation: X axis, Y axis, Z axis, Total	Scope to: Flexible bodies, a single rigid body, or Remote Point. Scope by: Bodies (single body only if rigid), location (Hit Point Coordinate), vertex, edge, face, user-defined Coordinate System, or user-defined Remote Point. Orientation coordinate system: Any: defaults to Global Cartesian.
Strain	Coupled Field Static, Coupled Field Transient, Static Structural, Transient Structural, Explicit Dynamics	Strain: Components, Principals, Normal X, Normal Y, Normal Z, XY Shear, YZ Shear, XZ Shear, Minimum Principal, Middle Principal, Maximum Principal, Intensity, Equivalent (von-Mises)	Scope to: Flexible body only. Scope by: Bodies, location (Hit Point Coordinate), vertex, edge, face. Orientation coordinate system: Any: defaults to Global Cartesian.
Stress	Coupled Field Static, Coupled Field Transient, Static Structural, Transient Structural, Explicit Dynamics,LS-DYNA	Stress: Components, Principals, Normal X, Normal Y, Normal Z, XY Shear, YZ Shear, XZ Shear, Minimum Principal, Middle Principal, Maximum Principal, Intensity, Equivalent (von-Mises)	Scope to: flexible body only. Scope by: Bodies, location (Hit Point Coordinate), vertex, edge, face. Orientation coordinate system: Any: defaults to Global Cartesian.
Position	Coupled Field Static, Coupled Field Transient, Static Structural, Transient Structural, Rigid Dynamics, Explicit Dynamics	Result Selection: X axis, Y axis, Z axis	Scope to: Rigid body only. Scope by: Bodies, coordinate system. Orientation coordinate system: Any: defaults to Global Cartesian.
Flexible Rotation Probe	Coupled Field Static, Coupled Field Transient, Static Structural, and Transient Structural	Rotation of X, Y, and Z axes (in the Global Coordinate System only)	Scope to: User-defined Remote Point or a Body. Note that this probe requires rotational degrees of freedom data (ROTX/ROTY/ROTZ), which is commonly associated with shell and beam bodies, but not solid bodies. If unavailable, the application displays result values of `0`.^[a]
Velocity	Coupled Field Transient, Transient Structural, Rigid Dynamics, Explicit Dynamics, LS-DYNA	Velocity: X axis, Y axis, Z axis	Scope to: Flexible or rigid body. Scope by: Bodies (single body only if rigid), coordinate system (rigid bodies only), location (Hit Point Coordinate), vertex, edge, face. Orientation coordinate system: Any: defaults to Global Cartesian.
Angular Velocity	Coupled Field Transient, Transient Structural, Rigid Dynamics	Angular Velocity: X axis, Y axis, Z axis	Scope to: Rigid body only. Scope by: Bodies. Orientation coordinate system: Any: defaults to Global Cartesian.
Acceleration	Coupled Field Transient, Transient Structural, Rigid Dynamics, Explicit Dynamics, LS-DYNA	Acceleration: X axis, Y axis, Z axis	Scope to: Flexible or rigid body. Scope by: Bodies (single body only if rigid), coordinate system (rigid bodies only), location (Hit Point Coordinate), vertex, edge, face. Orientation coordinate system: Any: defaults to Global Cartesian.
Angular Acceleration	Coupled Field Transient, Transient Structural, Rigid Dynamics	Angular Acceleration: X axis, Y axis, Z axis	Scope to: Rigid body only. Scope by: Bodies. Orientation coordinate system: Any: defaults to Global Cartesian.
Energy	Coupled Field Harmonic, Coupled Field Static, Coupled Field Transient, Static Structural, Transient Structural, Rigid Dynamics, Explicit Dynamics	For Static Structural and Transient Structural: Kinetic, Strain, Damping, Artificial, and Nonlinear Stabilization. For Rigid Dynamics: Kinetic, Potential, External, and Total For Coupled Field Harmonic: Kinetic, Potential, and Damping For Coupled Field Static and Coupled Field Transient: Kinetic, Strain, Damping, Artificial, Nonlinear Stabilization, and Total. For Explicit Dynamics: Internal, Kinetic, Plastic Work, Hourglass, Contact, and Total	Scope to your model using the Geometry property: System Energy is the default setting. Otherwise, only body scoping is supported for either flexible or rigid bodies. Scope by using the Result Selection property: For Transient Structural and Static Structural: All (default) energy types or per body for the Kinetic, Strain, Damping, Artificial, or Nonlinear Stabilization options. For Transient Rigid: All (default) energy types or per part for the Kinetic, Potential, External, and Total options. Note: For the External and Total options, you must use the System Energy setting for the Geometry property setting. For Coupled Field Harmonic: All (default) energy types or per body for the Kinetic, Potential, and Damping options. For Coupled Field Static and Coupled Field Transient: All, Kinetic, Strain, Damping, Artificial, Nonlinear Stabilization, and Total. For Explicit Dynamics: All (default) energy types or per body for the Internal, Kinetic, Plastic Work, Hourglass, Contact, and Total options.
Volume	Coupled Field Static, Coupled Field Transient, Static Structural, Transient Structural, Steady-State Thermal, Transient Thermal, Electric, and Thermal-Electric.	Volume	Scope to: Body. Scope by: Body.
Force Reaction^[b]	Coupled Field analyses, Static Structural, Transient Structural, Modal, Harmonic Response, Random Vibration, Response Spectrum, Explicit Dynamics^[c]	Force Reaction: X axis, Y axis, Z axis	Scope to: Flexible body, vertex, edge, face^[d], or element faces. In Explicit Dynamics analyses probes can also be scoped to faces, edges, and vertices of a rigid body. You can also scope to a section plane on a body by specifying Surface as the Location Method. Scope by: Boundary Condition^[e], Contact Region, Remote Points^[f], Beams^[f], Springs^[f], Mesh Connection, Surface^[g], or Named Selection. Orientation coordinate system: Any Cartesian: defaults to Global Cartesian. Solution Coordinate System is the only valid option for Random Vibration and Response Spectrum.
Moment Reaction ^[b]	Coupled Field analyses, Static Structural, Transient Structural, Modal, Harmonic, Random Vibration, Response Spectrum, Explicit Dynamics^[c]	Moment Reaction: X axis, Y axis, Z axis	Scope to: Flexible body, vertex, edge, face^[d], or element faces. In Explicit Dynamics analyses probes can also be scoped to faces, edges, and vertices of a rigid body. You can also scope to a section plane on a body by specifying Surface as the Location Method. Scope by: Boundary Condition^[e], Contact Region, Remote Points^[f], Beams^[f], Mesh Connection, Surface^[g], or Named Selection. Orientation coordinate system: Any Cartesian: defaults to Global Cartesian. Solution Coordinate System is the only valid option for Random Vibration and Response Spectrum. Summation point: Centroid or orientation coordinate system.
Joint	Static Acoustics, Static Structural, Transient Structural, Coupled Field Static, Coupled Field Transient, Explicit Dynamics, LS-DYNA, LS-DYNA Restart Analysis, Rigid Dynamics Analysis, and Ansys Motion^[h]	See Joint Probes	Scope to: Joints only. Orientation coordinate system: The Orientation Method property for joint probes is a read-only property set to Joint Reference System. However, even though this property indicates the Joint Reference System, the evaluated result displays in the evolved coordinate system based on the rotation of the joint. This property only supports Cartesian coordinate systems. The Joint Reference System option is the same for all joint result types. Summation point: Always at joint for Moment.
Spring	All analysis types including Rigid Dynamics and LS-DYNA^[h]	Elastic Force^[i], Damping Force^[j], Elongation, Velocity^[k]	Scope to: Spring only. Orientation coordinate system: Spring axis only.
Bearing	Coupled Field analyses, Static Structural, Transient Structural, Modal, Harmonic Response, Random Vibration, Response Spectrum	Elastic Force 1, Elastic Force 2, Damping Force 1, Damping Force 2, Elongation 1, Elongation 2, Velocity 1, Velocity 2	Scope to: Bearing only. Orientation coordinate system: Bearing axes only.
Beam	Coupled Field Static, Coupled Field Transient, Static Structural, Transient Structural, LS-DYNA^[h]	Axial Force, Torque, Shear Force at I, Shear Force at J, Moment at I, and Moment at J	Boundary Condition: Select beam.
Bolt Pretension	Coupled Field Static, Coupled Field Transient, Static Structural, Transient Structural, Random Vibration, Response Spectrum	Adjustment (Static and Transient Structural), Tensile Force	Scope by: Boundary condition (Y pretension bolt condition). Orientation coordinate system: Along pretension direction only.
Generalized Plane Strain	2D: Static Structural, Transient Structural	Rotation: X, Y: Moment: X, Y: Fiber Length Change: Force	Orientation coordinate system: Any: defaults to Global Cartesian.
Response PSD ^[l]	Random Vibration	X axis, Y axis, and Z axis. Displacement, Stress, Strain, Acceleration, Velocity	Scope to: Flexible body only. Scope by: Location (Hit Point Coordinate) and vertex. Orientation Coordinate System: Solution Coordinate System is the only valid option for Random Vibration.
Contact Distance	Rigid Dynamics Only	The varied distance between the Contact and Target sides of the specified Contact Region for each time point in the analysis.	Scope to: Contact Region. Scope by: Contact Region.

^[a]Solid bodies, which are composed of solid elements, have no rotational degrees of freedom, and therefore calculate maximum x, y, and z values as zero (Axis specified under the Results category equals 0). However, if a solid body shares nodes with shell bodies or line bodies and if the scoping includes the solid body only, then this probe can report non-zero values (resulting from the shared nodes). But these rotation values may not represent the rotation of the body as a whole. Furthermore, if the body shares nodes with an element whose nodes include rotational degrees of freedom, such as contact or spring elements, or some condition that has inherent motion, the probe may also produce rotation values that do not represent the rotation of the body.

^[b]Force Reactionand Moment Reaction probes:

Will not solve if scoped to a Contact Region that includes a rigid body.
Do not support Mesh Connections for Modal and Harmonic Response analyses.
Do not support the Location Method option Contact Region when the corresponding Contact Region is scoped to element faces.
A limitation exists when the scoping of a probe is applied to a geometric entity (Location Method = Geometry Selection) that shares more than one body. The (unscoped) elements that are adjacent to the scoped body contribute to the probe's results.

^[c]For Explicit Dynamics, the only valid options for the Location Method property are Geometry or Boundary Condition.

^[d]When you scope this result to geometry, including contact surfaces and cut surfaces, the application calculates the probe using element-nodal data. These calculations are equivalent to those of the FSUM command. That is, the sums for each component direction for the total selected node set and the nodal force and moment contributions of the selected elements attached to the node set.

Recommendation: You should examine your results carefully for geometry scoping. If all elements are selected, the sums of the result are usually zero except where constraints or loads are applied. Element-nodal results for geometry-based scoping should be the same as the node-based results when you specify Boundary Condition as the Location Method if the geometry-based scoping is the same as the boundary condition scoping. However, because of certain limitations associated with how Mechanical calculates scoping, and perhaps based on a model's geometry, the application may produce unexpected element-nodal results.

^[e]When you specify Boundary Condition as the Location Method, the application calculates Force Reaction or Moment Reaction probes using nodal data. These calculations are equivalent to those of the PRRSOL command, which provides the total reaction solution for the selected nodes.

^[f]Remote Points must be constrained and Beams and Springs must be grounded.

^[g]Setting the Location Method to Surface requires that you specify the following additional properties:

Surface: Select a construction Surface created using the Construction Geometry feature.
Geometry: Select the body or bodies that the construction Surface intersects (slices through).
Extraction: Option include Mesh From Positive Side (default) and Mesh From Negative Side. The probe only examines the elements cut by the plane and only the nodes of those elements which are on specified side of the plane, positive or negative. The positive side is in the positive local Z direction from the construction surface and negative side is in the negative local Z direction.

Note: Surfaces used for reaction probes do not currently intersect all geometries. For example, the feature does not intersect line bodies or bodies that include a joint, spring, or MPC contact.

Limitation: This option has certain inherent limitations. The probe’s results can be affected by:

An application employed tolerance as you cut through the mesh. This calculation creates a small thickness value. This could allow nodes not included in the construction surface to be used in the solution.
Facets shared by elements included in the construction surface.
Loads and constraints that produce a solution in the body that is essentially zero.

If you experience doubts about your result values, compare reactions scoped to a surface against the reaction solutions scoped to boundary conditions and scoped to contact elements.

^[h]For LS-DYNA, if your project was solved in a version earlier than 2020 R1, you will not be able to evaluate the following probes: Spring, Beam Connection, and Joint.

^[i]Random Vibration and Response Spectrum analyses support the Elastic Force result only.

^[j]The Damping Force result is calculated for Transient Structural analysis only when damping is defined.

^[k]Velocity result is calculated only for Static Structural, Transient Structural, Rigid Dynamics, and LS-DYNA analyses.

^[l]The Response PSD Probe provides an excitation response plot across the frequency domain of an input PSD load. It also evaluates the root mean square (RMS) and expected frequency of a response PSD. It is assumed that the excitations are stationary random processes from the input PSD values.

Note:

Refer to the Probe Details View section for additional information about the above scoping options.
For more information about Explicit Dynamics, see Force Reaction and Moment Reaction Result Trackers for Explicit Dynamics in the Explicit Dynamics Analysis Guide.
For a linked Mode-Superposition Harmonic Response analysis, the Expand Results From property (see Output Controls) in the Harmonic Response analysis must be set to Harmonic Solution in order to support the Elongation result.
For a linked Mode-Superposition Transient Structural analysis, the Expand Results From property (see Output Controls) in the Transient Structural analysis must be set to Transient Solution in order to support the Elongation result and, if damping is defined, the Damping Force result.

Differences in Probes Applied to Rigid Bodies

The following table describes the differences between probes applied to rigid bodies in an Explicit Dynamics analysis, compared to probes applied to rigid bodies in a Static Structural or Transient Structural analysis.

Characteristic	Explicit Dynamics Analysis	Static Structural or Transient Structural Analysis
How rigid part is meshed	Meshed with solid element containing multiple nodes.	Meshed as a single element containing a single node.
Centroid of the rigid part	Need not be represented by any node in the mesh. The Mechanical application computes the part centroid by averaging the element centroids. Each element centroid is the average of the element's nodes.	Results at the single node represent the displacement, velocity, etc. at the centroid of the part.
Display of minimum and maximum results	Probe applied to rigid body displays both the minimum and maximum results at a given time because there are multiple elements and nodes reporting results. The position probe represents the sum of the minimum (or maximum) displacement with the average nodal coordinate.	Probe applied to rigid body does not display both the minimum and maximum results at a given time because there is only one element and one node reporting results.

Characteristic

Explicit Dynamics Analysis

Static Structural or Transient Structural Analysis

How rigid part is meshed

Meshed with solid element containing multiple nodes.

Meshed as a single element containing a single node.

Centroid of the rigid part

Need not be represented by any node in the mesh. The Mechanical application computes the part centroid by averaging the element centroids. Each element centroid is the average of the element's nodes.

Results at the single node represent the displacement, velocity, etc. at the centroid of the part.

Display of minimum and maximum results

Probe applied to rigid body displays both the minimum and maximum results at a given time because there are multiple elements and nodes reporting results.

The position probe represents the sum of the minimum (or maximum) displacement with the average nodal coordinate.

Probe applied to rigid body does not display both the minimum and maximum results at a given time because there is only one element and one node reporting results.