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PLOAD4 on QUAD with Cylidrical Coordinate system problem

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jacksonfem

Structural
Dec 8, 2010
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On a QUAD 1x1, pinned at all nodes ( see the image ), I apply a constant pressure-traction (PLOAD4) at x-direction, with a magnitude of 10. The Tx reactions on each support is 2.5 as expected. Total X force = 10*1*1=10. Each support takes 10/4=2.5.
I create a Cylindrical Coordinate System (CORD2C) as it seems ( with Z axis colinear with Y global ), and applied again the same pressure (PLOAD4), with this CORD2C as reference (CID entry of PLOAD4).
The results on each support are:
Tx= 2.165
Tz = 0.72

The above result, less Tx than 2.5 and the non zero Tz, obviously means that Nastran takes as pressure surface a cylindrical one ( the radius is 0.50 ), so the load it is assumed to be something like the 3rd image.
The thing is that it's IMPOSSIBLE for me to generate the above reactions with whatever I tried.

Does anyone knows what Nastran does??

model_1_qvsvdl.jpg

model_2_cadfhw.jpg

model_3_xxirhz.jpg
 
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