Response functions

In Response Dynamics, you can evaluate the response for the current event. The software calculates responses in two steps:

Note:

For Quasi-Static events, the software calculates the static response; there is no modal response step.

Step 1. Calculates the modal responses.

Performed automatically when you perform a response evaluation (for example, using the Evaluate Nodal Function Response dialog box), if no modal responses already exist. However, you can also calculate the modal response without also performing a response evaluation (see Solve for modal response for steps).

• For transient response analysis, the software calculates modal responses at every time point, using time integration.

• For frequency and random response analysis, the software calculates the modal responses at every frequency.

Step 2. Calculates the physical responses.

Calculated for a given set of nodes or elements, at given time or frequency points.

• For transient, frequency, and random events, the software “recovers” the physical responses using either the Mode Displacement or Mode Acceleration data recovery method.

• For response spectrum events, the software calculates peak responses using modal approximation methods.

Depending on the type of evaluation you perform, the response results are stored in one of two formats: as functions in an AFU file, which you can plot as XY graphs, or as contour results in an RS2 file, which you can view as contour plots and animations.

The modal response calculated in the first step can be reused for different physical response calculations.

Note:

When the software calculates modal responses, the event and its excitation information are saved automatically to an Event Evaluation File (EEF), which you can later import to perform a restart analysis or to create a sequence of transient events, if desired.

Physical response types

Response Dynamics generates two types of physical response results:

• Response functions — Functions of time (time histories) or frequency (results over a range of frequencies) stored in AFU files. These functions appear in the XY Function Navigator and in the Events node of the Simulation Navigator, where you can plot them and analyze the result data. You can evaluate displacement, velocity, acceleration, and reaction force at a given node. You can evaluate stress, strain, element force, beam-element force, and shell stress resultant at a given element. Note: You can also generate a response function for each normal mode's response to the event excitations. For more information, see Modal response functions.Sample stress function (drop impact)

• Contour results — Contour plots generated over the entire model or over the selected events for a specific point in time or for a specific frequency. You can view contour results from the Event node in the Simulation Navigator or in the Post Processing Navigator.Sample stress contour results

Viewing multiple responses simultaneously

You can view your model, normal mode shapes, excitations, response functions, dynamic response results, FRF, and so on, simultaneously using viewports and layouts. For more information, see Layouts and viewports.

Model, displacement contour results, excitation function, and response function

How do I

Solve for modal response

Plot response functions

Learn more

Modal response functions

Nodal response functions

Elemental response functions

CSD response functions

Look up more details

Response function coordinate systems

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Response functions, Simcenter 3D 2021.1 Series

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