Learning Forum

[Tom Ber]

Hi, 

I would like to read the reaction moment probe from the contact in a large displacement analysis. When I use the summation method: orientation system or centroid, the moment is read relative to the undisplaced centroid of the contact. I need the summation point to be at the centroid of the displaced contact. Is there any way to do this automatically? The only solution I have found is to move the coordinate system exactly by the value the geometry moves, but this is too labor-intensive to do for many contacts and many timesteps.

 

When the summation point does not move with the mesh, this results in a false reading of the moments. 

 

[dlooman]

Does specifying a node number on the APDL SPOINT command update the location to compute the moment about?

[Tom Ber]

Hi dlooman,

Thanks for your reply but I don't understand what exactly you mean. Could you please clarify it further?

could you give me some example of apdl code that I could use?

 

[dlooman]

Assuming you know the x,y,z location of the centroid and have a named selection for the nodes on the surface the commands would be:

 

cmsel,s,named_selection

spoint,node(x,y,z) 

fsum

allsel

[helgaella99]

Using the summation method with a fixed orientation system or centroid often leads to incorrect moment readings since the summation point remains at the undisplaced centroid. Ideally, the summation Sprunked point should move with the displaced contact centroid to reflect true moments.