[GSOC] Draw method for Cable class

[shishir-11]

References to other Issues or PRs

Brief description of what is fixed or changed

This PR aims to track the progress of Phase 1 of GSOC project aimed to Extend the continuum_mechanics module.
Draw method is implemented for Cable and changes to the solver for consistency of equation with the lowest point.
Plot for tension also added .

Other comments

Release Notes

• physics.continuum_mechanics
  • A draw method to plot the Cable diagram as specified by the user
  • Changes to solver for consistency with lowest point
  • Plot for tension added

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• physics.continuum_mechanics

  • A draw method to plot the Cable diagram as specified by the user (#26640 by @shishir-11)

  • Changes to solver for consistency with lowest point (#26640 by @shishir-11)

  • Plot for tension added (#26640 by @shishir-11)

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#### Brief description of what is fixed or changed
This PR aims to track the progress of Phase 1 of GSOC project aimed to Extend the continuum_mechanics module.
Draw method is implemented for Cable and changes to the solver for consistency of equation with the lowest point.
Plot for tension also added .

#### Other comments


#### Release Notes

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* physics.continuum_mechanics
  * A draw method to plot the Cable diagram as specified by the user 
  * Changes to solver for consistency with lowest point
  * Plot for tension added
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Update

The release notes on the wiki have been updated.

[shishir-11]

@Ishanned @AdvaitPote this draft PR will track my Draw method progress. I will make a final PR when eveything is ready.
Please take a look at the discussion on Gitter as whenever I include rectangles, I am getting an error. I also get an error in my interactive shell when I use other draw methods. Any idea why that might be ?

[github-actions]

Benchmark results from GitHub Actions

Lower numbers are good, higher numbers are bad. A ratio less than 1
means a speed up and greater than 1 means a slowdown. Green lines
beginning with + are slowdowns (the PR is slower then master or
master is slower than the previous release). Red lines beginning
with - are speedups.

Significantly changed benchmark results (PR vs master)

Significantly changed benchmark results (master vs previous release)

Full benchmark results can be found as artifacts in GitHub Actions
(click on checks at the top of the PR).

[shishir-11]

Can you please check its working out once, I will move forward to adding the docstring for the new method and its usage if the diagrams are satisfactory.

[AdvaitPote]

The Supports seem to be changing as per the scale of the diagram/plot. Try and avoid this. Also, the distributed loads seem to look uneven too in different plots. In my opinion, the two plots should be a few millimeters apart at best. The second case is missing the force magnitude labelling too.

[shishir-11]

Shape of cable under UDL
It takes a parabolic shape under uniformly distributed loads if weight of cable is not considered. However in the current solver it allows taking a random lowest point, in the solver coefficients of a parabolic equations are calculated

however the method does not ensure the provided lowest point will be the lowest point of the formed equation. For example, in the case of same height of supports the solver would accept lowest_x as values other than the midpoint of left and right support and still produce a result which probably shouldn't happen.

In [1]: from sympy.physics.continuum_mechanics.cable import Cable
   ...: c=Cable(("A", 0, 10),("B", 20,10))
   ...: c.apply_load(0, ("X", 850))
   ...: c.solve(5,0)

In [2]: c.tension
Out[2]: {'distributed': 19125*sqrt((4*X/15 - 4/3)**2 + 1)/2}

In [3]: c.draw().show()

I have fixed the issue with the magnitude symbols disappearing and bad support shapes. For running draw use the order given above as without using solve , draw does not work.

[Ishanned]

Hi @shishir-11, can you share what happens if you call the draw method without calling solve first?

[shishir-11]

Hi @shishir-11, can you share what happens if you call the draw method without calling solve first?

The solve method takes arguements for the lowest point of the cable which is used to form the equation later. So calling draw without solve works fine for point loads , for distributed loads we would get an error trying to access the lowest point coordinates.

[AdvaitPote]

>>> from sympy.physics.continuum_mechanics.cable import Cable
>>> c = Cable(("A", 0, 10), ("B", 10, 10))
>>> c.apply_load(-1, ('Z', 2, 7.26, 3, 270))
>>> c.apply_load(-1, ('X', 4, 6, 8, 270))
>>> c.solve()
>>> c.draw().show()

I just ran this example locally. I am getting a good and correct diagram as expected. However, it's giving me a Runtime Warning: RuntimeWarning: invalid value encountered in wrapper_func (vectorized) outputs = ufunc(*inputs)
It's just a warning but still, it'll be better to maybe inspect a little. Kindly check if the function is encountering any None or infinite values in its computations.

[shishir-11]

Can

>>> from sympy.physics.continuum_mechanics.cable import Cable
>>> c = Cable(("A", 0, 10), ("B", 10, 10))
>>> c.apply_load(-1, ('Z', 2, 7.26, 3, 270))
>>> c.apply_load(-1, ('X', 4, 6, 8, 270))
>>> c.solve()
>>> c.draw().show()

I just ran this example locally. I am getting a good and correct diagram as expected. However, it's giving me a Runtime Warning: RuntimeWarning: invalid value encountered in wrapper_func (vectorized) outputs = ufunc(*inputs) It's just a warning but still, it'll be better to maybe inspect a little. Kindly check if the function is encountering any None or infinite values in its computations.

I'm unable to reproduce this warning on my system , can you provide any specifications or method to reproduce this.

[AdvaitPote]

I'm unable to reproduce this warning on my system , can you provide any specifications or method to reproduce this.

That's odd. If it's something with my device then no problem. Just focus on the 'adding distributed loads' feature. I am looking for possible changes and might post another review.

[shishir-11]

I have implemented the 'adding distributed load' feature in an earlier PR, please check.

mag = 0
for key in self._loads['distributed']:
    mag += self._loads['distributed'][key]

force_arrows.append(
    {
        'text':f'{mag} N/m',
        'xy':((self._left_support[0]+self._right_support[0])/2,self._lowest_y_global - max_diff*0.15)
    }
)

[AdvaitPote]

I don't see any more changes function wise. @Ishanned ?

[Ishanned]

I don't see any more changes function wise. @Ishanned ?

I'll have a final look and let you know

[Ishanned]

LGTM. After yesterday's discussion, I think we should merge this PR.