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ptc-50653371-Visitor
1-Visitor
April 17, 2013
Question

Need help on ploting a 3-D graph

  • April 17, 2013
  • 1 reply
  • 2419 views

Hello

I am new to PTC community and MathCAD, really need some help from expert. I am trying to plot a 3D graph with derived formulae in MathCAD, and then

compare this graph with the graph I generated with Excel. But I am having troubles in getting it work..... A number of errors or warnings appeared in my

programme. Whoever will help me, please also point out where I did wrong so I know what to do next time.

Thanks in advance!

1 reply

A
AndyWesterman12-Amethyst
12-Amethyst
April 17, 2013

Hello & welcome to the forum.

First problem is the usual confusion between the text subscript "." which just gives a readable name and the array/vector/matrix subscript operator "[" which allows you to reference elements within the matrix.

so when you type F[a Mathcad expects that a will have an integer value to specify the a'th element of the vector F

Attached I have modified the first few equations to show.

The next problems are that you are using the variable d in your equations but it has not been assigned a value

and the equation for σ.h has an empty place holder ( the equation is incomplete).

Both of these mean that Mathcad will highlight the items to show the error as best it can.

Once you correct these , σ.h, H, & rb should calculate & the next problem area will appear as Mathcad continues through the worksheet.

Hope this helps

Regards

Andy

P
ptc-50653371-VisitorAuthor
1-Visitor
April 17, 2013

Hello Andy

Thanks for your warm welcome. I follow your instruction and luckily get a answer for stress utilisation, Su. But, there are still some issues:

1. I was able to plot a surface graph with defined variables, please look into the programme and offer me some advice.

2. My ultimate aim is to produce a surface plot with x,y,z axis varying within a certain range, how exactly can I achieve this?

Thanks

Lee

A
AndyWesterman12-Amethyst
12-Amethyst
April 17, 2013

Hello Lee,

Now that the basic equations are working, the next step is to change them to functions of T and d since these are your variable inputs.

This does mean that you can no longer evaluate the equations directly but must calculate a specific case - for this work sheet T1 & d1 are the defined case.

Always useful to check that no errors creep in.

Then you need to define the ranges over which you want to calculate / plot.

Range variables as you had are possible but do cause problems in understanding.

d is easy as in the attachment

Capture.PNG

This creates a vector d

Capture.PNG

T is more difficult as it appears to be dependant on the value d, so this has been created as a 2 dimensional matrix - hopefully this is correct.

Capture.PNG

As the test case (above)shows, d[35 & T[15,35 are the same condition as you had originally & give the same value for S.u.

Regards

Andy

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