# How To Compute The Total Force Out Of Reaction Forces In A Model

Last Reviewed: 04/23/1999
TAN ID: 4007

Long Description:

Problem:
Customer wants to compute the total force out of reaction forces in
in his model.

Solution 1:
1) Import results in the usual way so you have reactions forces that you can postprocess.

2) Use Results, Create/Marker/Vector and plot the reaction forces for the case or time of interest.

3) With the vectors representing the reactions forces been shown in the viewport, use Fields, Create/Spatial/FEM, choose Continuous, Vector, give a name to the field, highlight the group, apply.

4) Go to Load Cases, and create a fake, empty load case making it current -give it a name, apply. You will use this load case to create false loads with the reactions forces you computed.

5) Go to Loads/BCs, and use Create/Force/Nodal, give it a name, click into input data, click in the force panel, highlight/click on the field you created in step 3, Ok the form. Select the nodes for which
you want to compute the total sum of the reactions forces, add to the application region, apply. You may create several loads like this for different sets of nodes you want a total for.

6) Use (shareware) Utilities, Loads/BCS, LBC Resultants…, select one of the force loads you just created above, click on Update LBC List, click on Settings, click Draw Forces ON, OK, Apply. You will see the resultant vectors displayed in the viewport although not in the correct location. However the component magnitudes of the resultant force will be correct. These numbers will also appear on a spreadsheet window and they will also be written in the journal and session files..

CONGRATULATIONS !

The total reaction force can also be calculated (since 1994) by:

Utilities-Results-Results Utilities
Set Action=Show; Object=Nodes; Method=Summation
Use the “Select Results” button to select a vector result (e.g. Reaction Forces)
Select Node 1: # and hit Apply

By default, the total reaction force in X, Y and Z direction shows up in a spreadsheet. When the magnitude is needed, just check the toggle “Derive Scalar Results From” and set the option menu to “Magnitude”.

Also when multiple result cases are selected, the total reaction force for each result case is displayed in a spreadsheet (or written to file).

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Another way is to use the Shareware utilities Results Toolbox
Load the reaction force results as a vector into Res1
Then just click on Info (bottom right corner) and a summary appears including the Sum, Average, Min and max.