Mohr Circle's program.

Programming Questions

matheus.p..

in Programming Questions • 21 days ago

Hello,

I'm trying to make a program that makes the Mohr Circle. Basically it is a way to calculate all the forces on a sample from a buiding, and makes a graph on how it should look like.

I'm having some trouble to create a text field where the user inputs the values from the forces acting on the sample, and to show them after the Circle is done.

hmmm, I think is hard to understand like that... hmm A simpler way to look at my problem is:

I need to make a field where the user enter some values and after some calculations it shows the results to the person, with the accurate circle representation.

Does anyone knows how it can be done using the Processing??

It should look just like this:

http://www.isr.umd.edu/~austin/book.d/playground.d/mohr.html

Thank you for your time =D

Replies(9)

cageehv

Hey Matheus,

Just use the formulas:

Assuming we know the stress components $\sigma_x$ , $\sigma_y$ , and $\tau_{xy}$ at a point $P$ in the object under study, as shown in Figure 4, the following are the steps to construct the Mohr circle for the state of stresses at $P$ :

Draw the Cartesian coordinate system $(\sigma_\mathrm{n},\tau_\mathrm{n})$ with a horizontal $\sigma_\mathrm{n}$ -axis and a vertical $\tau_\mathrm{n}$ -axis.
Plot two points $A(\sigma_y, \tau_{xy})$ and $B(\sigma_x, -\tau_{xy})$ in the $(\sigma_\mathrm{n},\tau_\mathrm{n})$ space corresponding to the known stress components on both perpendicular planes $A$ and $B$ , respectively (Figure 4 and 6), following the chosen sign convention.
Draw the diameter of the circle by joining points $A$ and $B$ with a straight line $\overline{AB}$ .
Draw the Mohr Circle. The centre $O$ of the circle is the midpoint of the diameter line $\overline{AB}$ , which corresponds to the intersection of this line with the $\sigma_\mathrm{n}$ axis.

source:
http://en.wikipedia.org/wiki/Mohr%27s_circle

Rolf
( http://cagewebdev.com/index.php/tag/processing/)

matheus.p..

Re: Mohr Circle's program.

21 days ago

Ooh the formulas i`ve got it, my problem is how to make the user enter the values from the stress components, show the processed components and move the graph with them.

The simple code i can make preatty fast, the problem is using the processing UI, like the Textfield, etc. etc

cageehv

Re: Re: Mohr Circle's program.

21 days ago

Hey Matheus,

Check out the ControlP5 library:

http://www.sojamo.de/libraries/controlP5/

(and there are other good GUI libs too)

Good luck!

Rolf
( http://cagewebdev.com/index.php/tag/processing/)

cageehv

Re: Mohr Circle's program.

21 days ago

oops, saw I messed up my link in these posts... silly me!

right link is:
http://cagewebdev.com/index.php/tag/processing/

matheus.p..

Re: Mohr Circle's program.

21 days ago

I was using the ControlP5 xD

What about that other link from cageweb. I don`t see how that should help me,sorry.

The only think i'm lacking to do my project is a way for the user input the values, and the program to grab them and do the math.

and i can't find it anywhere >.< It is such a simple thing that is making me frustrated... >....>

quarks

Re: Mohr Circle's program.

20 days ago

The only think i'm lacking to do my project is a way for the user input the values

Perhaps I am missing something but the ControlP5 library has a textfield control, but you seem to have dismissed this library. Is there a reason why?

matheus.p..

Re: Mohr Circle's program.

20 days ago

Actually i was trying to make the textfield control to work.. and was getting my ass handed to me....

Well i did it.. I found an old post here in the foruns that have a similar problem to mine.

Here is the Solution that i found.

import controlP5.*;
ControlP5 controlP5;

Textfield myTextfieldA;
Textfield myTextfieldB;

void setup () {
size (400,400);
frameRate (25);
controlP5 = new ControlP5( this );

myTextfieldA = controlP5.addTextfield( "textA" ,100,160,200,20);
myTextfieldA.setAutoClear( false );

myTextfieldB = controlP5.addTextfield( "textB" ,100,200,200,20);
myTextfieldB.setAutoClear( false );
}

void draw () {
background (0);
}

public void textA( String theText) {
changeNumber(myTextfieldB, theText);
}

public void textB( String theText) {
changeNumber(myTextfieldA, theText);
}

void changeNumber(Textfield theField, String theText) {
float n = float (theText);
if (! Float .isNaN(n)) {
n = 1-n;
theField.setText( "" +n);
}
else {
println ( "not a number " );
}
}

quarks

Re: Mohr Circle's program.

20 days ago

The clue is in the name textfield - it holds text and when you retrieve it you are getting a String. So the problem was not getting a 'textfield' to work it was converting a String to a float.

Glad you found a solution.

matheus.p..

Re: Mohr Circle's program.

20 days ago

exactly, i could not do anything with a string since i'm only working with numbers, but with that code, i managed to make an error script, if the person does not use a valid number, AND get the text on the ' box ' to become a float.