Reaction Moment extraction

Dear Altair Team,

I have constrained the rectangular beam in one end (all dof fixed) and applied Angular displacement in other end (120deg angular displacement applied along axis of rod using spcd). Could you please explain how to extract the torque or moment produced at fixed end due to angular displacement. Also explain how to create the graph between the torque vs applied angular displacement.

Thank you.

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Simon Križnik

Hi,

you have to request the SPC reaction forces:

ANALYSIS->CONTROL CARDS->GLOBAL_OUTPUT_REQUEST

SPCFORCE(H3D,ALL) = ALL

Later on, you can show the forces in Hyperview as contour plot (SPCF forces) or (better) as vector plot.

Then you can plot torque vs applied angular displacement using cross-plot

https://community.altair.com/community?id=community_question&sys_id=c586c83a1b2bd0908017dc61ec4bcb4e

Altair Forum User

Hi,

you have to request the SPC reaction forces:

ANALYSIS->CONTROL CARDS->GLOBAL_OUTPUT_REQUEST

SPCFORCE(H3D,ALL) = ALL

Later on, you can show the forces in Hyperview as contour plot (SPCF forces) or (better) as vector plot.

Then you can plot torque vs applied angular displacement using cross-plot
https://community.altair.com/community?id=community_question&sys_id=c586c83a1b2bd0908017dc61ec4bcb4e

Hi,

Here I have to extract reaction torque or reaction moment and not the reaction forces.

How to take the reaction moment at fixed end and please explain with fem file.

Thank you.

Simon Križnik

I have found the following issues in the model you shared:

1. The SPCD units for rotational degrees-of-freedom is radians, so instead of 120, it should be 2.0944 radians to get 120 degrees rotation.

2. The model undergoes large rotations so large displacement analysis should be activated (PARAM/LGDISP=1 and PARAM/HASHASSM)

3. Convergence control was activated through the nonlinear expert system PARAM/EXPERTNL/YES

4. CNTSTB is redundant since there is no contact

5. ANALYSIS->CONTROL CARDS->GLOBAL_OUTPUT_REQUEST> SPCFORCE(H3D,ALL) = ALL was defined to output SPC forces AND moments (see image)

<?xml version="1.0" encoding="UTF-8"?>

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Altair Forum User

I have found the following issues in the model you shared:

1. The SPCD units for rotational degrees-of-freedom is radians, so instead of 120, it should be 2.0944 radians to get 120 degrees rotation.

2. The model undergoes large rotations so large displacement analysis should be activated (PARAM/LGDISP=1 and PARAM/HASHASSM)

3. Convergence control was activated through the nonlinear expert system PARAM/EXPERTNL/YES

4. CNTSTB is redundant since there is no contact

5. ANALYSIS->CONTROL CARDS->GLOBAL_OUTPUT_REQUEST> SPCFORCE(H3D,ALL) = ALL was defined to output SPC forces AND moments (see image)

<?xml version="1.0" encoding="UTF-8"?>

Hi Ivan,

Thanks for your suggestions.

Could you please explain me how to create the graph for moment vs angle for this job.

Thank you.

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Simon Križnik

You have to request the rotations with analysis>control cards> GLOBAL_OUTPUT_REQUEST > DISPLACEMENT>ROTATIONS>ROTA

in Hypergraph plot the moment and rotations (mind the node IDs, in your case 153 &154) and then use the cross-plot mentioned before or directly set the appropriate X & Y type requests to plot in one go.

<?xml version="1.0" encoding="UTF-8"?>

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