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Two Overhang Beam with UDL - Moment diagram Problem - Messages
#1 Posted: 2/20/2023 11:33:13 AM
I have attached a mathcad file.. and the moment diagram at the end doesn't match
with expcted output.. it should have gone smoothly to end with x coordinate 5m.
but at certain point it has jumped to postive rigion.
Please help fix it.
Thanks
File not found.File not found.
with expcted output.. it should have gone smoothly to end with x coordinate 5m.
but at certain point it has jumped to postive rigion.
Please help fix it.
Thanks
File not found.File not found.
#2 Posted: 2/20/2023 5:05:51 PM
I have no idea why mathcad plots that segment faulty.
But it is possible to plot correct graphic in SMath.
However SMath integration is not very good and fast.
It will take much more time than mathcad, and zig-zagy.
You can improve plot by increasing Integrate: Accuracy.
It is in Tools>Options>Calculation.
Regards
PS: I increased accuracy to 500 to get a decent plot.
It took 50 seconds to plot in the picture!!
Integration should really be improved.
UDL.sm (18 KiB) downloaded 36 time(s).

But it is possible to plot correct graphic in SMath.
However SMath integration is not very good and fast.
It will take much more time than mathcad, and zig-zagy.
You can improve plot by increasing Integrate: Accuracy.
It is in Tools>Options>Calculation.
Regards
PS: I increased accuracy to 500 to get a decent plot.
It took 50 seconds to plot in the picture!!
Integration should really be improved.
UDL.sm (18 KiB) downloaded 36 time(s).
#3 Posted: 2/20/2023 6:14:20 PM
In the interactive handbook you can find examples for beam analysis.
They use symbolic integration and equation solving with Maxima. This is very fast, except for the Maxima restart at the beginning of the sheet (can be removed if all works well).
example maxima beam.sm (41 KiB) downloaded 31 time(s).
They use symbolic integration and equation solving with Maxima. This is very fast, except for the Maxima restart at the beginning of the sheet (can be removed if all works well).
example maxima beam.sm (41 KiB) downloaded 31 time(s).
Martin Kraska
Pre-configured portable distribution of SMath Studio: https://en.smath.info/wiki/SMath%20with%20Plugins.ashx
#4 Posted: 2/21/2023 2:35:40 AM
Sorry but I have problem again
with M(5m)=-0.2083 kN m
it should have been
M(5m)=0
with M(5m)=-0.2083 kN m
it should have been
M(5m)=0
#5 Posted: 2/21/2023 2:42:21 AM
WroteSorry but I have problem again
with M(5m)=-0.2083 kN m
it should have been
M(5m)=0
My sorry it is correct.. since it is overhang it should have moment at the end;;
#6 Posted: 2/21/2023 2:49:22 AM
#7 Posted: 2/21/2023 4:46:08 AM
Hi. Remembering that solving an ODE is also told to integrate it:
UDL.sm (22 KiB) downloaded 31 time(s).

The domain can also be restricted to M(x) by multiplying it by the corresponding inequalities.
Best regards.
Alvaro.
UDL.sm (22 KiB) downloaded 31 time(s).
The domain can also be restricted to M(x) by multiplying it by the corresponding inequalities.
Best regards.
Alvaro.
2 users liked this post
#8 Posted: 2/21/2023 10:02:18 AM
WroteMy sorry it is correct.. since it is overhang it should have moment at the end;;
Finite Differences [FD] is a very good yardstick insensitive to noise.
It that what you mean moment at the end ?
Cheers ... Jean.
Page2 FD.sm (57 KiB) downloaded 18 time(s).
#9 Posted: 2/21/2023 11:29:30 AM
WroteHi. Remembering that solving an ODE is also told to integrate it:
The domain can also be restricted to M(x) by multiplying it by the corresponding inequalities.
Best regards.
Alvaro.
This is a marvelous solution.
I learned a new thing today.
Thanks Razonar.
Maybe I am wrong but I think formula should be like this.
Huge kN*m values appear if calculated as in the picture above.
Regards
1 users liked this post
Alvaro Diaz Falconi 2/21/2023 2:49:00 PM
#10 Posted: 2/21/2023 12:55:20 PM
ODE integrator(s) range from exact [rarely]
approx. 4 decimals ... to glorious freak !
64 bits Smath does not have 32 bits Matlab ODE.
Recently checked on my PC2 this damned bug.
Cheers ... Jean.
ODE 0 TEST [17].sm (45 KiB) downloaded 20 time(s).
Revisit from few months ago.
approx. 4 decimals ... to glorious freak !
64 bits Smath does not have 32 bits Matlab ODE.
Recently checked on my PC2 this damned bug.
Cheers ... Jean.
ODE 0 TEST [17].sm (45 KiB) downloaded 20 time(s).
Revisit from few months ago.
#11 Posted: 2/21/2023 2:51:56 PM
WroteMaybe I am wrong but I think formula should be like this.
Huge kN*m values appear if calculated as in the picture above ...
Hi overlord. You're absolutely right. Thanks for catching that error. Only 3 orders of magnitude. Who could worry about that? The Mathcad block can also be used, although I don't know if this is the best way to deal with the units, using an intermediate function Mo.
UDL.sm (26 KiB) downloaded 34 time(s).
Best regards.
Alvaro.
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