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Mathcad help :(

Forum|Forum|13 years ago
April 12, 2013
9 replies
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Hello, my name is Alex and i am a student at the Polytechnic University of Bucharest.

I have never used this software before and it is getting very dificult finding what i need.

My industrial design teacher has given me some equation stuff to work, but i never used mathcad.

I have to create in mathcad 2 cylinders that would intersect and after that make some calculations.

The first is vertical and the second should passthrough the first but horizontaly, i've attached a photo, hope this will be usefull.

He explained me that there ar 3 scenarios i need to test, all based on assigning a diferent value to "d".

Please help if can

Other

Best answer by Werner_E

I don't know what the real needs are, either.

It looks to me as if the graph which is described is the flatprojection/unrolling of the intersection of two orthogonal cylinders of same size. d being some kind of offset. d=r meaning that the axis of the cyliniders intersect and the cylinder intersection collapsed into two ellipses which unroll to two sines. But then, i may be wrong - the formulas I came up with are slightly different from those posted.

W

Werner_E

25-Diamond I

Please attach a Mathcad worksheet with what you had tried so far.

What are you after? equations? 2D-plots? 3D-plots?

A

AlanStevens

19-Tanzanite

See attached. It should at least show you how to start.

Alan

1_ydRxfunction-xmcd.zip

P

ptc-5043076

Author

1-Visitor

Hello, thank you for replying so short.

The plot is 2D, i will reply as soon as i can.

I am getting a wrong format error, i am using Mathcad Prime 2.0

I must appologize, i dont know about anything about inserting radical equations.

Regards,

Alex.

A

AlanStevens

19-Tanzanite

Here is a Prime 2 version.

Alan

1_yRdx-mcdx.zip

P

ptc-5043076

Author

1-Visitor

Thank you Alan, thats just wow what you did there, i wish i could find a starter tutorial on mathcad

A

AlanStevens

19-Tanzanite

Alexandru Hera wrote:
... i wish i could find a starter tutorial on mathcad

Click on help (the question mark at the top-right of Prime 2). There is a tutorial there:

Alan

P

ptc-5043076

Author

1-Visitor

For better explaining Alan, hope you can understand exacly whan i need

the first scenario allows me to alocate multiple values to d and represent them.

A

AlanStevens

19-Tanzanite

Alexandru Hera wrote:
For better explaining Alan, hope you can understand exacly whan i need
...

Err...no!

1. What is the orientation of your 2nd cylinder? 2. What, exactly is it you are trying to calculate? Your first post suggested a number of discrete values of d. Are you now looking for a plot of y as a function of d?

I'm afraid I'll need a more detailed explanation/better drawings (make them 3D?).

Alan

P

ptc-5043076

Author

1-Visitor

Well, i am trying to calculate y based on the d value, 2d not 3d

The orientation is straight throught the first, like a nail.

P

ptc-5043076

Author

1-Visitor

Making this subject up

Alan what you did was what i needed, now that i got more details i would like to know if you can help me take this a bit further.

But for the record, my teacher was impressed

@Werner: the graph you made was really usefull as i got max points for this preview.

A

AlanStevens

19-Tanzanite

Glad to have helped. To get further help with Mathcad related problems you only need to post your questions here and I and/or others will probably help.

Alan

P

ptc-5043076

Author

1-Visitor

Okay, to get started, the title of the paper.

Graphic-analytical study of the curve of intersection of two cylinders of rotation

R - circles radius (same size)

d - distance between the cylinders axes

M (m,m') - intersection point

x = Rα (from the horizontal projection)

α = x/R

W

Werner_E

25-Diamond I

So at least a sketch worth the paper drawn on.

As far as I see its exactly the same thing we had before with one exception. The distance d is now more meaningful. In the equation of your first posting the variable d was the difference from R and the new variable d now, This would affect the equation, of course as d=0 now means we have two ellipses as intersection and therefore two sines as flat projection, and d=R would mean a curve without inflection points - exactly the opposite from the prior post.

The equation would be

and if the goal is graphing, then Alan had already provided the way to do.

Think its time for you to fire up Mathcad and create your own worksheet. Come back if there is anything not working.

BTW, in your sketch (is it yours?) you have different x-axis with different meaning - can be confusing.

P

ptc-5043076

Author

1-Visitor

Well, from the paper i have y^2= R^2 - (d-x1)^2, but thats so close.

I'll get to work.

P

ptc-5043076

Author

1-Visitor

I've tried to reproduce the results, failed at plot

1_Lucrare-mcdx.zip

W

Werner_E

25-Diamond I

Alexandru Hera wrote:
I've tried to reproduce the results, failed at plot

Whats wrong? Plots look OK here?

You don't see the lower half of y8 because above you have written y15:=stack(... instead of y8:=stack(...

You did this with other vectors, too, so I guess you are not sure what that command y8:=stack(y8,-y8) is for.

It simply stacks the points of the upper half (y8) on top of the points of the lower half of the curve and it would make more sense to assign it a variable with the same number (y8). As you have written it you would have to draw y2 to see the plot for d=14 which doesn't seem to be that comfortable.

1_Lucrare_2-mcdx.zip

P

ptc-5043076

Author

1-Visitor

Yes, but how is it made with mathcad? cuz i want to modifiy the graph for any scenario in the theory, and for every y value.

Hmm, here are the other 2 scenarios.

#1 - Case when d = R

#2 - Case when d = 0

#3 - Case when 0 < d < R

W

Werner_E

25-Diamond I

Alexandru Hera wrote:
Yes, but how is it made with mathcad? cuz i want to modifiy the graph for any scenario in the theory, and for every y value.

I sent you all I have - unfortunately in MC15 format. If you can't model it in another software (preferably a 3D CAD for better results) you may consider using the free 30day eval version of Mathcad15.

Find attached a pdf from that file. At least plotting the two cylinders should work the same in Prime - plotting the intersection in 3D will need some different rework but probably is not necessary at all.

If you are just after a pic for every case you could use one of the animations I posted, pause the film, pull the slider to the position you want and take a screen shot.

Good luck!

1_Zylinder.pdf

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