Response Dynamics – Analyzing a transient event

1: Setup

This activity continues with the Simulation and result files you saved when you completed the Response Dynamics – Setting up the FEM tutorial. Make sure the Simulation file you saved in that tutorial is open and the Simulation file is the displayed file. If the Simulation file is not the displayed file, do the following:

Simulation Navigator

Simulation File View

rs_bracket_1_sim1
Make Displayed Part

2: Reset dialog box memory

The options you select in dialog boxes are preserved for the next time you open the same dialog box within a given session. Restore the default settings to ensure that the dialog boxes are in the expected initial state for each step of the activity.

File

Preferences→User Interface

Options

Reset Dialog Memory

OK

3: Create an acceleration pulse function

Use Function Tools for Response Dynamics to create a 1 mm/s² acceleration pulse function for use in your dynamic excitation.

Note:

For your convenience, the completed pulse function is also included in the provided response_functions.afu file.

Response Dynamics

Function Tools for Response Dynamics (Response Dynamics group→Tools list)

Note:

This utility requires the Java Runtime Environment (JRE) version 8 or later. You can install the JRE from www.oracle.com.

You must set the following environment variables, either in your ugii_env.dat file or using the Override Java Parameters command:

UGII_JVM_OPTIONS=-Xmx64M
UGII_JVM_LIBRARY_DIR=[path to the \bin\server folder in the JRE installation]

Transient

Pulse

Half-sine
Amplitude: 1.0 (default)
Pulse Range: 0.02

Number of Cycles

1

Number of Intervals

128

Ordinate Type

Acceleration

Unit Type

mm/s²

Record Name

half_sine_pulse_1

Browse

Browse to a location on your computer and enter a file name in which to store the function.

Save

The function is saved in the AFU file you specify (an AFU file is a storage file for table functions).

OK

the Function Tools for Response Dynamics utility

4: Plot the pulse function

Use the Functions and Graphing tools to plot the pulse function.

XY Function Navigator

rs_bracket_1_sim1→your function name
Note:

If you did not create the pulse function in the previous step, right-click the supplied response_functions file, and select Load. Then expand the response_functions node.
half_sine_pulse_1
Plot (XY)
Create New Window (Viewport dialog box)
In a later step, you will scale the function.
Graph Window 1

5: Create a transient event

Simulation Navigator

New Event (Response Dynamics group)

Type

Transient

Name

Transient_Analysis_1

Data Recovery

Mode Displacement

Duration Option

User Defined

Duration Time

0.5

Initial Conditions

Zero

Setting the initial conditions to zero specifies that at the start of the simulation event, the model is undeformed (the modal displacements are zero).

OK

6: Create an excitation

New Translational Nodal Excitation (Response Dynamics group→Tools list)

Name

enforced_motion_1

Excitation

Enforced Motion

Selection Method

Graphic Selection

Select enforced motion location (Select Object)
(the enforced motion location on the top edge of the back face)
Z

The Z check box is the only selectable direction, and should be selected by default. You can apply this excitation only in the Z direction because this enforced motion location was defined in the Z direction (see the previous Response Dynamics activity for more information).
Function Manager

Function list (Record Name column)
half_sine_pulse_1

Select the pulse function you created in the previous step.

OK

XY Function Manager dialog box

Scale Factors

Z

49000

This is the scaling value for your general 1 mm/s² function.

OK

New Translational Nodal Excitation dialog box

7: Generate a nodal function response

Generate a response function to evaluate the acceleration in the Z direction at the CONM2 element/mesh point.

Evaluate Nodal Functions (Response Dynamics group→Tools list)

Result

Acceleration

Response Node

Node (Select Node)

Response Request

Data Component

Data Component

Z

Store to AFU

OK

This function represents the response at the CONM2 element for the duration of the transient event.

Create New Window (Viewport dialog box)
Graph Window 1

In the Simulation Navigator, notice that the Status column now displays “Active, Locked” for the RS_Meta_Solution_1 solution process. When you solve for a response function or response results, the solution process is locked. Because there are result files associated with the event, you cannot edit the attributes of the event, nor can you add excitations. To unlock the solution process, you would need to delete the modal response and response function results.

8: Generate an elemental function response

Evaluate the von Mises stress at an element on the bracket fillet.

Simulation Navigator

Transient_Analysis_1 (under RS_Meta_Solution_1)
Evaluate Function Response→Elemental

Result

Stress

Response Element

(Select Elements)
(any element in the fillet)

Response Request

Data Component

Vonmises

Store to AFU

OK

Create New Window (Viewport dialog box)
This function represents the von Mises stress at the selected element for the duration of the transient event. Note that the highest stress is approximately 1.556E+005 kPa.
Graph Window 1

9: Divide the display into two viewports

Next you will evaluate the response of the entire model at specific time points of maximum and minimum acceleration. In preparation for this task, you will divide your graphics window into two viewports and then plot your nodal response function in one of the viewports.

Results

Upper and Lower (Layout group)

Simulation Navigator

Response Functions (under Transient_Analysis_1)
1_(1Z+)
Plot(XY)
the bottom viewport in the graphics window

Note:

When you initially created the nodal function response and elemental function results, the graphs used real values. However, by default a function graph uses the magnitude values, as shown above.

Change the graph to display the real values instead of the magnitude values.

Complex Options (XY Graph group)

Plot

Real Only

OK

10: Find the minimum and maximum acceleration

Probe the response function to find the minimum and maximum acceleration of the dynamic response.

Peak Probing Mode (XY Graph group→More list)

the Help Line
Drag the Help Line to the highest point on the graph curve (to probe the maximum acceleration).
Drag the information boxes for the peak over to a position where you can read them.
Note the maximum acceleration.

The value displayed will depend on the element that you selected.
Repeat the above steps to probe the minimum acceleration.

Close (turn probing mode off)

11: Generate displacement contour results

Generate the entire model's response at the time points of minimum and maximum acceleration.

Simulation Navigator

Transient_Analysis_1
Evaluate Contour Results→Response

Requested Results

Displacement
Stress

Response Node

Node (Select Node)
In the upper viewport, drag a selection box across the entire model to select all the nodes.
From XY Graph (Method)
The From XY Graph method lets you select the time points to evaluate from a plotted function. Alternatively, you can use the Start/End Point method and enter these time point values manually.

Point Value

1_(1Z+)

OK

Equation Selection dialog box

the viewport in your graphics window that contains the plotted response function
the highest point in the graph curve (select the maximum acceleration point from the previous step)
the lowest point in the graph curve
OK

Notice that the two point values you selected now appear in the Point Value list in the dialog box. The two values should be close to the maximum (1.6400E-002) and minimum (3.12500E-002) time points that you marked on the graph curve.

OK

This step generates the response of the entire part at the time points of minimum and maximum acceleration.

Return to Model (Context group)

the lower viewport

Later in this activity, you will view the contour results.

12: Generate stress contour results

Next, you will evaluate Stress Response Results for all elements on the model, and select the time point in the response function where stress is highest. Use the following steps, referring to the previous step for details if necessary:

In the Evaluate Response Results dialog box, select the Stress check box in the Requested Result group. Clear the Displacement check box.
Select all the elements in the model.
In the Method group, click From XY Graph.
Under Point Value, click .
In the Equation Selection list, select 2_(16E_VONMTOP) and click OK.

Note:

The file name may be different based on the element that you selected when you generated the elemental stress function in a previous step (the number 16 in the above file name is the element ID).
In the plotted elemental stress function, select the time point where stress is highest, and then click OK to generate the response results.

In the next step, you will view the contour plot of these stress results as well as the displacement results you generated earlier.

13: View displacement contour results

Results

Single View (Layout group)

Post-Processing Navigator

RS_Meta_Solution_1
Transient_Analysis_1
Load
Transient_Analysis_1→Response Results 1→Increment 1→Displacement – Nodal
Z
Plot
Note the minimum and maximum displacements at Iteration 1 (displacement at maximum acceleration). Try viewing other result types for other direction components at this time point and at Iteration 2 (minimum acceleration).

Return to Model (Context group)

14: View stress contour results

Post-Processing Navigator

Response Results 2→Increment 1→Stress – Element – Nodal
Von-Mises
Plot
Note that the highest stress occurs at the fillet, as discovered from the elemental stress response function.

Save

File

Close→All Parts