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  • Thread starter Thread starter stevit
  • Start date Start date

stevit

Guest
Good evening to all, in these quarantine days I am putting hand to a university exam since in normal days time is missing.
what I would like to do is measure the torsion rigidity of a kart chassis. to model it I used the pipe model and to carry out the simulation I created an infinitely rigid element at the height of the front hubs at whose ends I applied two loads that create the bending moment.
I must have made some mistakes in the code because I can't see the deformed frame in the /post, plus I ask you for help on how to measure the shift of knots for the calculation of torsion stiffness.
I'll bring you the code... thanks to all for the collaboration
do not mind the correspondence between the tube data and those that appear in the code, I was just doing tests the "right" data will put them at the end, once the code will give something likely.

finish
_
_
/prep7

/title, kart chassis
Frame pipe fittings
That's right.

ro30=30
(3.14*ro30*2)-(3.14*ri30**)
I don't know.
== sync, corrected by elderman ==
ro16=16
Material characteristics
!material 1: steel
mp,ex,1,206000
mp,prxy,1,0.33
mp,dens,1,7.85e-06

!material 999: infinitely rigid
mp,ex,999,206000*10000
mp,prxy,999,0.33
mp,dens,999,7.85e-06

Characteristic fem elements
esize,12
/eshape,1

element 1: tubular round section beam for frame (fi30)
et,1,288,,3!1 internal library, beam188
sectype,1,pipe
secreted, 30,5
element 2: tubular round section beams for supports (fi16)
et,2,288 !2 internal library, beam188
sectype,2,pipe
secreted, 20,10

K,1,-500,150
K,2,-250,450,70
K,3,-150,150
K,4,,150
K,5,50,150
K,6,300,350
k,7,450,500
k,8,650,500
k,9,800,500
k,10,950,500
K,101,-500,-150
k,202,-250,-450,70
K,303,-150,-150
K,404,-150
K,505,50,-150
K,606,300,-350
k,707,450,-500
k,808,650,-500
k,909,800,-500
k,10010,950,-500
k,11,300,270
K,12,450,420
K,13,650,420
K,14,800,420
k,15,950,420
K,16,250,60
k,17,-500,50
K,18,-500,-50
K,19,300,70
K,20,300,-70
K,21,240,70
K,22,240,-70
K,23,130,20,300
K,24,130,-20,300

k,25,-250,550,70
k,26,-250,-550,70


!

I,1,2
l,2,3
l,3,4
l,4,5
l,5,6
l,6,7
l,7,8
I,8,9
l,9,10
l,101,202
l,202,303
l,303,404
l,404,505
l,505,606
l,606,707
l,707,808
l,808,909
l,909,10010
l,6,606
I, 11,12
I,12,13
l,13,15
I,8,13
I,13,808
I,1,101
I,9,14

lfillt,25,1,40
lfillt,25,10,40
lfillt,2,3,40
lfillt,11,12,40
lfillt,4,5,40
lfillt,13,14,40
lfillt,6,7,40
lfillt,15,16,40
lfillt,20,21,40

lsel,s,line,1,35
cm,tel,line
All the way


Support lines

l,16,17
l,16,18
I,19,21
l,20,22
I,21,23
l,22,24

lfillt,38,40,40
lfillt,39,41,40

lsel,s,line,36,43
cm,supp,line
All the way


!line for torsion rigid element

l,25,2
l,2,202
l,202,26
lsel,s,line,44,46
cm,tors, lines
All the way

cmsel,s,tel
type,1
secnum,1
lmesh,all
All the way

cmsel,s,supp
type,2
secnum,1
lmesh,all
All the way

cmsel,s,tors
type,1
secnum,1
lmesh,all
All the way

Ksel,s,kp,16
No.
d,all,ux
d,all,uy
d,all,uz
d,all,rotx
d,all,roty
d,all,rotz
All the way

Ksel,s,kp,9
No.
d,all,ux
d,all,uy
d,all,uz
d,all,rotx
d,all,roty
d,all,rotz
All the way

Ksel,s,kp,909
No.
d,all,ux
d,all,uy
d,all,uz
d,all,rotx
d,all,roty
d,all,rotz
All the way

Ksel,s,kp,23
No.
d,all,ux
d,all,uy
d,all,uz
d,all,rotx
d,all,roty
d,all,rotz
All the way
Ksel,s,kp,24
No.
d,all,ux
d,all,uy
d,all,uz
d,all,rotx
d,all,roty
d,all,rotz
All the way

Ksel,s,kp,25
fk,all,fz,1000
All the way

ksel,s,kp,26
fk,all,fz,-1000
All the way


finish
/solu
The
finish


/posts
eplot
pldisp,1
 
according to me you should locate the torsion axis and then calculate the corners of torsion by hand or with an electronic sheet as a relation between shifts in the transversal planes divided the distances from the torsion axis
 
Okay thanks for the advice. and instead for the calculation of tensions how can I do? I used the command

plnsol,s,eqv but I do not visualize anything (while for deformed I have no problem)
 

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