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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:
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!
And now! i am stuck😥
I make a light mc file for add to this post
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
😥
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
great! for different value,
it comes from me because the values of the points have changed slightly
It is possible to keep the formalism of mechanical load, because it's clearer for mechanical readers
I rewrite first matrix, in second equation , with correct values
But i see a problem in first line
if i solve that
the calculation does not converge ...😓
Please attach your worksheet.
Success!
Luc
it's strange
if i rewrite the vector value: i modify the red point value
The matrix is now:
And the calculation is done
I don't see a compelling reason for these programs of yours. You can just write:
and
to get the two matrices.
Success!
Luc
see attached file
it's strange, i copy paste in new sheet.
If i switch this matrix
The calculus run but it's wrong
if i use the matrix as in picture, the calculus is good
if i switch , it's wrong
For the upper left matrix, the determinant is 0, it means the matrix is singular, or in other words, it cannot be inverted.
That means that lsolve cannot find a solution.
For the lower left matrix that's not the sae, and lsolve can find a solution.
Success!
Luc
however there are other things that don't work
If i move the Bpoints the geometrical value was changed.
The calculation run
but key result are curious ?
If i calculate this manually, i find approximately:
FB1 = -202569,41
FB2 = -194324,39
FB3 = -194325,75
XO = 584902,22
YO = 0,16
ZO = 13455,71
and the worksheet give
see attached full worksheet (sorry it is written in french)
I have only a vague idea of what your calculations are about.
My responses have been from a(n almost pure) mathematical viewpoint, and knowledge of Mathcad/Prime,
just trying to streamline your calculations and potentially reducing the amount of typing (which is a general source of error).
Success!
Luc