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Threshold1-Visitor
1-Visitor
May 25, 2014
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Trying to build Mohr's Circle in mathcad

  • May 25, 2014
  • 19 replies
  • 11970 views

I beleive im very close to figuring this out. I was able to find a previous example yet I cant seem to get things just quite right. My biggest problem is units and scaleing the axes. Im I asking too much if somebody was willing to look it over and tell me where im screwing things up?


And my second question is with the axis lables. Is there a way to have them automatically update with the correct units? Say I want to use this template but instead of being in ksi I now want to me in Pa (pascals). Or do I just have to go in and manually change it every time.

Best answer by Werner_E

There are two sources which where important for my learning of Mathcad - the built-in help with its quicksheets, etc. and the Mathsoft Collab Forum, the predecessor of this community, which was so poorly and faulty integrated here by PTC staff (most of the old threads are broken, links to other post don't work and attachments are missing). Sometimes you still may be able to find some gems, though.

There are a lot of interesting things you can do with scripted components (look at Richards fine collection to get an idea: http://communities.ptc.com/docs/DOC-1071), but I have chosen a more simple web control because it does the job well enough, is easy to setup, in my opinion web controls have the better look and you are not going to be asked if you want to disable scripting whenever you open that sheet.

19 replies

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Werner_E25-Diamond I
25-Diamond I
May 25, 2014

Whats the reason for the multiplication with 10^-6 in the plot? Shouldn't it be 1.45*10^-7 to turn Pa into ksi?

You reversed the ordinate - negative values at the top, positive values below. Was this done on purpose?

When you plot with units its best to make the expression unitless by dividing by the unit, So plot x(theta)/unit und unit may be ksi.

BTW, I see that you still have two unanswered questions pending - lost interest?

R
RichardJ19-Tanzanite
19-Tanzanite
May 25, 2014

Divide each quantity by the desired unit.

You can make it easier to change units by assigning your desired unit to a variable, and then dividing each quantity by that. You should also assign theta explicitly using a range variable. Mathcad's quickplot feature does not always choose the best range (as you will see if you disable the assignment!).

Unfortunately, there is no way to automatically change the axis labels.

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Werner_E25-Diamond I
25-Diamond I
May 25, 2014

OK, so here is my attempt.

Unfortunately, there is no way to automatically change the axis labels.

I remember that a long time ago Stuart had posted a component where all(?) those parameters of a 3D plot where accessible by variables. He used it for some kind of "inplace animation". I don't know how he component was created and if it would be possible to do the same with a 2D plot.

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RichardJ19-Tanzanite
19-Tanzanite
May 25, 2014

Here's that worksheet. The 3D plot component in Mathcad is an OLE object. Stuart figured out which file it was and enough of the properties to create a scripted component in Mathcad. I think there was another worksheet based on this, but I can't find it. You could create a 2D plot using this by fixing the orientation of the 3D plot. Doing something with the built-in 2D plots is not possible, because they can't be accessed as a public object.

I think a better approach would be to use the routines from the Amazing Images book to create axes and labels as parts of the plot, and disable the graph axes. That would be quite a lot of work though!

V
VladimirN24-Ruby IV
24-Ruby IV
May 27, 2014

Hi,

The following document can be useful:

http://communities.ptc.com/docs/DOC-1291

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Werner_E25-Diamond I
25-Diamond I
May 27, 2014

I am not sure but compared to Greg's sheet I guess this is exactly the example which Greg wrote about in his first post that he found and worked on to derive his own version.

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fahmed-31-Visitor
1-Visitor
February 8, 2016

Guys I think I found a way to plot units in Mathcad for Mohr Circle

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