---------- Forwarded message ----------
From: Durve Sanjiv (External) <[email protected]>
Date: Thu, Jan 12, 2017 at 6:40 PM
Subject: RE: SingularityFunction in sympy.physics.continuum_mechanics.beam
To: SAMPAD SAHA <[email protected]>
Sampad,
Thanks for your reply and interest. You can add Sympy group in this thread
– I have no problem just send me a link.
I think my question was not very clear. I am sorry about that.
My problem is a beam fixed at both ends with a concentrated load of 6 units
in the center. Theoretical answer for M1 and M2 is 6*4/8 = 3.
When I run the following script,
from sympy.physics.continuum_mechanics.beam import Beam
from sympy.functions import SingularityFunction
from sympy import symbols, Piecewise, plot
E, I, x = symbols('E, I, x')
R1, R2 = symbols('R1, R2')
M1, M2 = symbols('M1, M2')
b = Beam(4, E, I)
b.apply_load(R1, 0, -1)
b.apply_load(6, 2, -1)
b.apply_load(R2, 4, -1)
b.apply_load(M1, 0, -1)
b.apply_load(M2, 4, -1)
b.bc_deflection = [(0, 0), (4, 0)]
b.bc_slope = [(0, 0), (4, 0)]
print b.boundary_conditions
#b.solve_for_reaction_loads(R1, R2)
b.solve_for_reaction_loads(R1, R2,M1,M2)
print b.load
print b.shear_force()
print b.bending_moment()
print b.slope().subs({E:1,I:1})
print b.deflection().subs({E:1,I:1})
I get following output
In [*2*]: runfile('C:/UserApps/Python27/Lib/site-packages/xy/problem01.py',
wdir='C:/UserApps/Python27/Lib/site-packages/xy')
{'slope': [(0, 0), (4, 0)], 'deflection': [(0, 0), (4, 0)]}
M1*SingularityFunction(x, 0, -1) + M2*SingularityFunction(x, 4, -1) + (-M1
- 3)*SingularityFunction(x, 0, -1) + (-M2 - 3)*SingularityFunction(x, 4,
-1) + 6*SingularityFunction(x, 2, -1)
M1*SingularityFunction(x, 0, 0) + M2*SingularityFunction(x, 4, 0) + (-M1 -
3)*SingularityFunction(x, 0, 0) + (-M2 - 3)*SingularityFunction(x, 4, 0) +
6*SingularityFunction(x, 2, 0)
M1*SingularityFunction(x, 0, 1) + M2*SingularityFunction(x, 4, 1) + (-M1 -
3)*SingularityFunction(x, 0, 1) + (-M2 - 3)*SingularityFunction(x, 4, 1) +
6*SingularityFunction(x, 2, 1)
Traceback (most recent call last):
File "<ipython-input-2-febc462b31fc>", line 1, in <module>
runfile('C:/UserApps/Python27/Lib/site-packages/xy/problem01.py',
wdir='C:/UserApps/Python27/Lib/site-packages/xy')
File "C:\UserApps\Python27\lib\site-packages\spyderlib\
widgets\externalshell\sitecustomize.py", line 685, in runfile
execfile(filename, namespace)
File "C:\UserApps\Python27\lib\site-packages\spyderlib\
widgets\externalshell\sitecustomize.py", line 71, in execfile
exec(compile(scripttext, filename, 'exec'), glob, loc)
File "C:/UserApps/Python27/Lib/site-packages/xy/problem01.py", line 28, in
<module>
print b.slope().subs({E:1,I:1})
File "C:\UserApps\Python27\lib\site-packages\sympy-1.0.1.
dev0-py2.7.egg\sympy\physics\continuum_mechanics\beam.py", line 455, in
slope
slope_curve = slope_curve.subs({C3: constants[0][0]})
IndexError: list index out of range
In [*3*]: b.reaction_loads
Out[*3*]: {M2: M2, M1: M1, R2: -M2 - 3, R1: -M1 - 3}
I expect to get something like {R2:-3,R1:-3,M1:3, M1:3}
I can understand that the problem I am trying to solve has indeterminacy of
2 and that is why my script is missing some additional statements.
Once this appears in the thread, I will pursue this because it is an
intersting problem for a hobbyist like me.
Thanks for the help.
Regards,
Sanjiv Durve
Ex- I I T Kanpur (1976)
*From:* SAMPAD SAHA [mailto:[email protected]]
*Sent:* 12 January 2017 12:34
*To:* Durve Sanjiv (External)
*Subject:* Re: SingularityFunction in sympy.physics.continuum_mechanics.beam
Sorry for the late reply.
I tried it in my system. I am getting {R2: -3, R1: -3} as output for the
reaction forces.
Can you please share us your outputs and also the problem statement which
you are trying to solve?
And one more thing, it is absolutely fine contacting me directly at my
gmail but still it is more preferrable that you post these queries into the
Sympy group and CC other developers. This way you don't have to wait for
long and can get very quick response as there are many active developers
working on Sympy currently.
If you don't mind Can I add Sympy Group in this thread?
Regards
Sampad Kumar Saha
Mathematics and Computing
I.I.T. Kharagpur
On Tue, Jan 10, 2017 at 10:29 PM, Durve Sanjiv (External) <
[email protected]> wrote:
Hello Sampad,
I have been trying to solve a fixed beam problem with concentrated load at
the center of the beam using sympy. You seem to have done a wonderful job
of implementing SingularityFunction. I hope you don’t mind me contacting
you directly at your gmail.
I have the following code which does not give the correct bending moment at
the fixed ends. The line * b.bc_slope = [(0, 0), (4, 0)] *seems to
have no effect
Is there a quick fix or let me know if I am missing something. I also tried
introducing M1, M2 and then commented out (shown in bold lines)
Your help would be appreciated.
from sympy.physics.continuum_mechanics.beam import Beam
from sympy.functions import SingularityFunction
from sympy import symbols, Piecewise, plot
E, I, x = symbols('E, I, x')
R1, R2 = symbols('R1, R2')
M1, M2 = symbols('M1, M2')
b = Beam(4, E, I)
b.apply_load(R1, 0, -1)
b.apply_load(6, 2, -1)
b.apply_load(R2, 4, -1)
*#b.apply_load(M1, 0, -1)*
*#b.apply_load(M2, 4, -1)*
b.bc_deflection = [(0, 0), (4, 0)]
b.bc_slope = [(0, 0), (4, 0)]
print b.boundary_conditions
b.solve_for_reaction_loads(R1, R2)
*#b.solve_for_reaction_loads(R1, R2,M1,M2)*
print b.load
print b.shear_force()
print b.bending_moment()
print b.slope().subs({E:1,I:1})
print b.deflection().subs({E:1,I:1})
p2 = plot(b.shear_force(),(x,0,4))
p3 = plot(b.bending_moment(),(x,0,4))
p1 = plot(b.slope().subs({E:1,I:1}),(x,0,4))
p4 = plot(b.deflection().subs({E:1,I:1}),(x,0,4))
Regards,
Sanjiv Durve
____________________________________________________________
__________________________________________
Confidentiality: This e-mail and its attachments are intended for the above
named only and may be confidential. If they have come to you in error you
must take no action based on them, nor must you copy or show them to
anyone; please reply to this e-mail and highlight the error.
____________________________________________________________
__________________________________________
************************************************************
******************************
CONFIDENTIALITY NOTICE
This e-mail and any attachment are confidential and may be privileged or
otherwise protected from disclosure. It is solely intended for the
person(s) named above. If you are not the intended recipient, any reading,
use, disclosure, copying or distribution of all or parts of this e-mail or
associated attachments is strictly prohibited. If you are not an intended
recipient, please notify the sender immediately by replying to this message
or by telephone and delete this e-mail and any attachments permanently from
your system.
--
You received this message because you are subscribed to the Google Groups
"sympy" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at https://groups.google.com/group/sympy.
To view this discussion on the web visit
https://groups.google.com/d/msgid/sympy/CANzav4FHQWk-CG1uMou0p6W7ttrcmjShDmfFJfT4wGMhV8xRrw%40mail.gmail.com.
For more options, visit https://groups.google.com/d/optout.
