[GiDlist] Uniform load distribution

Moderator: GiD Team

Benedictus Benny Po

[GiDlist] Uniform load distribution

Postby Benedictus Benny Po » Mon Nov 01, 2004 9:25 pm

Hello GiD fans, users and experts wherever you are,

I want to share with you my problem that I have and hope to get any solutions and suggest from you.
I'm devoloping interface between FEAP and GiD 7.2 at my institute for my Master Thesis. I would like GiD to generate uniform load to be distributed along the nodes I have after mesh generation. This load generation result in form of single nodal loads over every node along the line will be used in FEAP as input for LOAD macro editor:

LOAD
node1, X-coor ,Y-coord ,p_x, p_y
node2, X-coor ,Y-coord, p_x, p_y
node3, X-coor ,Y-coord, p_x, p_y
...etc.......

My .cnd file :


NUMBER:5 CONDITION:Face-Load
CONDTYPE:over lines
CONDMESHTYPE:over nodes
QUESTION:L1.....(length of constant uniform load)
VALUE:10 (m)
QUESTION:n_x....(Number of face elements (which are under uniform load) to be generated)
VALUE:4
QUESTION:q_x...(Uniform Load x direction)
VALUE:0.0
QUESTION:q_y...(Uniform Load y direction)
VALUE:-10 (kN/m)
QUESTION:p_x..(Nodal load x direction)
VALUE:0.0
QUESTION:p_y#FUNC#(Cond(4,real)*Cond(1,real)/Cond(2,int)*0.5).....(nodal load y direction)
VALUE:Autocalculate
STATE:hidden


and my .bas file :

*Set Cond Face-Load *nodes *Canrepeat
*If(CondNumEntities(Int)0)
LOAD
*loop nodes *onlyInCond
*Nodesnum *NodesCoord(1,real) *NodesCoord(2,real) *cond(p_x,real) *cond(p_y,real)
*End loop nodes
*endif

The result I have in my .dat file is like that:
(for L1=10(m), n_x=4 and q_y = -10(kN/m))
LOAD
Node X-coor Y-Coord p_x p_y
1, 0.00, 0.0, 0.0, -12.5
2, 2.50, 0.0, 0.0, -12.5
3, 5.00, 0.0, 0.0, -12.5
4, 7.50, 0.0, 0.0, -12.5
5, 0.00, 0.0, 0.0, -12.5

I did not see any possibility to tell GiD that at node 2, 3 and 4, since they get two times the half of the load from left element and right element, they should be each -25 , instead of -12.5.
If I would use in my .cnd file CANREPEAT: yes after CONDMESHTYPE: nodes,
I would get the same list of LOAD as above once more time , and it's still not correct.
The correct result should be :
LOAD
Node X-coor Y-Coord p_x p_y
1, 0.00, 0.0, 0.0, -12.5
2, 2.50, 0.0, 0.0, -25
3, 5.00, 0.0, 0.0, -25
4, 7.50, 0.0, 0.0, -25
5, 10.00, 0.0, 0.0, -12.5

I hope you understand what I meant and I'm looking forward to hearing from you.

Best regards,
Benedictus Benny PO





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Enrique Escolano

[GiDlist] Uniform load distribution

Postby Enrique Escolano » Tue Nov 02, 2004 11:12 am

You can use Tcl language for enhanced features.
Can call a tcl procedure from the bas file with the *tcl command

This is a sample:
File .cnd Define a condition over lines, over face elements (not over nodes), for example, named Face-Load
NUMBER: 1 CONDITION: Face-Load
CONDTYPE: over lines
CONDMESHTYPE: over face elements
QUESTION: Pressure
VALUE: 0.0
HELP: Pressure on line to be transferred as equivalent nodal loads
END CONDITION

File .bas Call a tcl procedure, named SampleLoadWriteNodalLoads
...
*tcl(SampleLoadWriteNodalLoads)
...

File .tcl Define this tcl procedure.

proc SampleLoadWriteNodalLoads { } {
#set a {{10 1 - 3} {2 1 - 3} {6 3 - 3} {1 1 - 3}}
set infocond [GiD_Info conditions Face-Load mesh]
foreach item $infocond {
set elem [lindex $item 0]
set face [lindex $item 1]
set pressure [lindex $item 3]
set infoelem [GiD_Info mesh elements Triangle $elem]
if { $face == 1 } {
set n1 [lindex $infoelem 1]
set n2 [lindex $infoelem 2]
} elseif { $face == 2 } {
set n1 [lindex $infoelem 2]
set n2 [lindex $infoelem 3]
} else {
#assumed face==3 ,only for triangles
set n1 [lindex $infoelem 3]
set n2 [lindex $infoelem 1]
}
set c1 [lrange [GiD_Info mesh nodes $n1] 1 end]
set c2 [lrange [GiD_Info mesh nodes $n2] 1 end]
set dist [::MathUtils::VectorDistance $c1 $c2]
set force [expr {$dist*$pressure*0.5}]
if { [info exists F($n1)] } {
set F($n1) [expr {$F($n1)+$force} ]
} else {
set F($n1) $force
}
if { [info exists F($n2)] } {
set F($n2) [expr {$F($n2)+$force} ]
} else {
set F($n2) $force
}
}
set result "LOAD\n"
append result "Node F\n"
foreach node [array names F] {
append result "$node $F($node)\n"
}
return $result
}

This procedure requires the last 7.5.0b GiD beta version.
GiD_Info (or .gid.central.s info) is a tcl procedure defined by GiD to return internal information.(read GiD help about Tcl-Tk extension)
The other command are Tcl standard (can see more information about Tcl/Tk language from the Internet)

I attach a zip file with this sample problemtype source.

Regards
Enrique Escolano
----- Original Message -----
From: Benedictus Benny Po
To: gidlist at gatxan.cimne.upc.es
Sent: Monday, November 01, 2004 8:45 PM
Subject: [GiDlist] Uniform load distribution


Hello GiD fans, users and experts wherever you are,

I want to share with you my problem that I have and hope to get any solutions and suggest from you.
I'm devoloping interface between FEAP and GiD 7.2 at my institute for my Master Thesis. I would like GiD to generate uniform load to be distributed along the nodes I have after mesh generation. This load generation result in form of single nodal loads over every node along the line will be used in FEAP as input for LOAD macro editor:

LOAD
node1, X-coor ,Y-coord ,p_x, p_y
node2, X-coor ,Y-coord, p_x, p_y
node3, X-coor ,Y-coord, p_x, p_y
...etc.......

My .cnd file :

NUMBER:5 CONDITION:Face-Load
CONDTYPE:over lines
CONDMESHTYPE:over nodes
QUESTION:L1.....(length of constant uniform load)
VALUE:10 (m)
QUESTION:n_x....(Number of face elements (which are under uniform load) to be generated)
VALUE:4
QUESTION:q_x...(Uniform Load x direction)
VALUE:0.0
QUESTION:q_y...(Uniform Load y direction)
VALUE:-10 (kN/m)
QUESTION:p_x..(Nodal load x direction)
VALUE:0.0
QUESTION:p_y#FUNC#(Cond(4,real)*Cond(1,real)/Cond(2,int)*0.5).....(nodal load y direction)
VALUE:Autocalculate
STATE:hidden


and my .bas file :

*Set Cond Face-Load *nodes *Canrepeat
*If(CondNumEntities(Int)0)
LOAD
*loop nodes *onlyInCond
*Nodesnum *NodesCoord(1,real) *NodesCoord(2,real) *cond(p_x,real) *cond(p_y,real)
*End loop nodes
*endif

The result I have in my .dat file is like that:
(for L1=10(m), n_x=4 and q_y = -10(kN/m))
LOAD
Node X-coor Y-Coord p_x p_y
1, 0.00, 0.0, 0.0, -12.5
2, 2.50, 0.0, 0.0, -12.5
3, 5.00, 0.0, 0.0, -12.5
4, 7.50, 0.0, 0.0, -12.5
5, 0.00, 0.0, 0.0, -12.5

I did not see any possibility to tell GiD that at node 2, 3 and 4, since they get two times the half of the load from left element and right element, they should be each -25 , instead of -12.5.
If I would use in my .cnd file CANREPEAT: yes after CONDMESHTYPE: nodes,
I would get the same list of LOAD as above once more time , and it's still not correct.
The correct result should be :
LOAD
Node X-coor Y-Coord p_x p_y
1, 0.00, 0.0, 0.0, -12.5
2, 2.50, 0.0, 0.0, -25
3, 5.00, 0.0, 0.0, -25
4, 7.50, 0.0, 0.0, -25
5, 10.00, 0.0, 0.0, -12.5

I hope you understand what I meant and I'm looking forward to hearing from you.

Best regards,
Benedictus Benny PO




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