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XDN14-Alexandrite
14-Alexandrite
April 1, 2021
Question

Mechanical torsors

  • April 1, 2021
  • 1 reply
  • 4833 views

Hi

I want to solve a mechanical torsors problem, but I don't know how to go about it with Mathcad

I have a circular platform. on this platforme i have 3 point B1,B2,B3

on each point i have a forces, respectively F1,F2,F3. About it i know directional vector for each forces.

My platform have a spherical joint in this center (point C).

And i have a torsor which define exterior mechanical load applied on platform at C point.

 

1°/ i write mechanical component:

Capture d’écran 2021-04-01 171405.png

obviously expressed respectively at each point

 

 Now, i want to solve it find FB1,FB2,FB3,X,Y,Z

 

 

For this, i want to make a torsors transportation on C point!Capture d’écran 2021-04-01 171743.png

 

And now! i am stuck😥

 

I make a light mc file for add to this post

 

1 reply

X
XDN14-AlexandriteAuthor
14-Alexandrite
April 1, 2021

And after all torsors transportation, i want to solve the system like this example:

Resultant theorem:
/ X : -0,9911.FB1 -0,9911.FB2 -0,9911.FB3 +XO = 0
/ Y : 0,1152.FB2 -0,1152.FB3 +YO = 0
/ Z : -0,1330.FB1 +0,0665.FB2 +0,0665.FB3 +ZO -12000 = 0
resultant moment theorem :
/ X : 0,0669.FB2 -0,0003.FB3 -1115 = 0
/ Y : 188,3112.FB1 -94,1556.FB2 -94,1556.FB3 +66000 = 0
/ Z : 164,0736.FB2 -163,0825.FB3 = 0

 

 

and finally:

FB1 = 16463,46
FB2 = 16763
FB3 = 16864,87
XO = 49646,1
YO = 11,74
ZO = 11953,37

 

 

I can to solve it with pen and paper, but i can't do it with mathcad

I can see that there is a problem with symbolic evaluations

😥

 

L
LucMeekes23-Emerald IV
23-Emerald IV
April 1, 2021

LucMeekes_0-1617292601229.png

 

My answers are different from yours. I may have made an error somewhere...

Anyway, you should be able to do this in Prime.

 

Success!
Luc

 

X
XDN14-AlexandriteAuthor
14-Alexandrite
April 2, 2021
in fact from a mechanical point of view, this means that the forces go towards infinity in the singular geometric position ?🙄
 
in your new calculation, if i use initial geometrical configuration the result are:
Capture d’écran 2021-04-02 110711.png
obviously this is absurd
 
If i slip a bit the geometrical value, the result are conform to your screenshot in you precedent post.
these values seem correct to me.
For mechanical design, these values do not need to be very precise
 
Perhaps it is possible to evaluate the geometrical parameter just before singularity 🤔
I don't know how to do that
 
in any case thank you very much for your very precious help🙂
and I understand better your first approach
 
 
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