NFORCE vs FSUM 1

[PedroCarneiro22]

Hi,

Can someone please explain what the differences between the Nforce are and Fsum command.
in what applications are they used?

Thanks

 

[petb]

FSUM [pre]Sums and prints, in each component direction for the total selected node set,
the nodal force and moment contributions of the selected elements attached to the node set.[/pre]

NFORCE [pre]Sums and prints, in each component direction for each selected node, the nodal force and moment contributions of the selected elements attached to the node. [/pre]

NFORCE includes the FSUM command, but also lists the individual contribution from each node.

 

[PedroCarneiro22]

Thanks for the answer.

I understand the definitions.

But for example i tried a simple of case of a double simple supported beam and if i select only one element and one node of this element the NFORCE and FSUM commands are not given the same result. According to the definitions the results should be the same right?

 

[petb]

Ok,
Can you share a small APDL-snippet that reproduces this behaviour?

 

[PedroCarneiro22]

Find in annex a simple example.
In this case if a fixed supported beam with a uniform distributed load.

 

[PedroCarneiro22]

Annex

 

[PedroCarneiro22]

I think that I already understand it is related with the point where FSUM is doing the momentum equilibrium.

 

[petb]

They should indeed be the same, when I run your code I get the same output from both FSUM and NFORCE. The code below shows a typical usage of fsum and nforce, and they behave as they should:

[pre]
/prep7
k,
k,2,1
k,3,2
l,1,2
l,2,3
et,1,189
lesize,all,,,4
lmesh,all
DK,1,UY, , ,0,UX,UZ,ROTX,ROTY, , ,
DK,2, ,,, , ,UY,UZ
DK,3, ,,, , ,UY,UZ
F,8,FY,1000
!*
MPTEMP,,,,,,,,
MPTEMP,1,0
MPDATA,EX,1,,200e9
MPDATA,PRXY,1,,0.3 !*
SECTYPE, 1, BEAM, CTUBE, , 0
SECOFFSET, CENT
SECDATA,0.001,0.002,0,5,0,0,0,0,0,0,0,0
SECTYPE, 1, BEAM, CTUBE, , 0
SECOFFSET, CENT
SECDATA,0.001,0.002,0,5,0,0,0,0,0,0,0,0
allsel
FINISH
/SOL
solve
/post1
set,last
ETABLE,MI,SMISC,3
ETABLE,MJ,SMISC,16
PLLS,MI,MJ,1,0

spoint,8
nsel,s,loc,x,0,0.75
fsum
nforce
[/pre]


Hopefully this can give some guidance.
Cumprimentos
Peter

 

[PedroCarneiro22]

Thanks for you help.