Thread Subject: Yield strength

Hello everyone,
I have many results of a tensile test, the data are x & y columns; x is strain and y is stress.
To calculate the Yield strength, I need to plot the data and at x=0.2% draw a line parallel to the initial line.
Since, I have too many files, I was wondering if someone know a way to automate this process.
Thanks,
Hesham

"Hesham" <heltaher.nospam@mathworks.com> wrote in message <glac7l$nh8$1@fred.mathworks.com>...
> Hello everyone,
> I have many results of a tensile test, the data are x & y columns; x is strain and y is stress.
> To calculate the Yield strength, I need to plot the data and at x=0.2% draw a line parallel to the initial line.
> Since, I have too many files, I was wondering if someone know a way to automate this process.
> Thanks,
> Hesham

well, plotting should be easy. then i suppose you would need to find the points where x<.2% and do a linear regression to get the slope of the line, then plotting that shouldn't be too hard.

looping through the data for different tests depends on the files, but with the 'dir' command you can get a listing of files in a directory and then loop through the list, read a file, create the plot, save it, and go on to the next one.

"Hesham" <heltaher.nospam@mathworks.com> wrote in message <glac7l$nh8$1@fred.mathworks.com>...
> Hello everyone,
> I have many results of a tensile test, the data are x & y columns; x is strain and y is stress.
> To calculate the Yield strength, I need to plot the data and at x=0.2% draw a line parallel to the initial line.
> Since, I have too many files, I was wondering if someone know a way to automate this process.
> Thanks,
> Hesham

Hello,
I think that it is rather simple task. Could you send me a testing file? i'll tryto manage it.
Mira

On Thu, 22 Jan 2009 14:41:02 -0500, David <dave@bigcompany.com> wrote:

> "Hesham" <heltaher.nospam@mathworks.com> wrote in message
> <glac7l$nh8$1@fred.mathworks.com>...
>> Hello everyone,
>> I have many results of a tensile test, the data are x & y columns; x is
>> strain and y is stress.
>> To calculate the Yield strength, I need to plot the data and at x=0.2%
>> draw a line parallel to the initial line.
>> Since, I have too many files, I was wondering if someone know a way to
>> automate this process.
>> Thanks,
>> Hesham
>
> well, plotting should be easy. then i suppose you would need to find
> the points where x<.2% and do a linear regression to get the slope of
> the line, then plotting that shouldn't be too hard.
>
> looping through the data for different tests depends on the files, but
> with the 'dir' command you can get a listing of files in a directory and
> then loop through the list, read a file, create the plot, save it, and
> go on to the next one.


For the looping part:

I faced something similar where I had to do a set of computations for a
large number of data files.
I customized a MATLAB central submission (RDIR), my version is here:
http://www.mathworks.com/matlabcentral/fileexchange/22544

"Miroslav Balda" <miroslav.nospam@balda.cz> wrote in message <glai85$2it$1@fred.mathworks.com>...
> "Hesham" <heltaher.nospam@mathworks.com> wrote in message <glac7l$nh8$1@fred.mathworks.com>...
> > Hello everyone,
> > I have many results of a tensile test, the data are x & y columns; x is strain and y is stress.
> > To calculate the Yield strength, I need to plot the data and at x=0.2% draw a line parallel to the initial line.
> > Since, I have too many files, I was wondering if someone know a way to automate this process.
> > Thanks,
> > Hesham
>
> Hello,
> I think that it is rather simple task. Could you send me a testing file? i'll tryto manage it.
> Mira
Thank you Mira,
Here is a link to a sample file:
http://tinyurl.com/cr8csy
H

"Hesham" <heltaher.nospam@mathworks.com> wrote in message <glave2$qob$1@fred.mathworks.com>...
> "Miroslav Balda" <miroslav.nospam@balda.cz> wrote in message <glai85$2it$1@fred.mathworks.com>...
> > "Hesham" <heltaher.nospam@mathworks.com> wrote in message <glac7l$nh8$1@fred.mathworks.com>...
> > > Hello everyone,
> > > I have many results of a tensile test, the data are x & y columns; x is strain and y is stress.
> > > To calculate the Yield strength, I need to plot the data and at x=0.2% draw a line parallel to the initial line.
> > > Since, I have too many files, I was wondering if someone know a way to automate this process.
> > > Thanks,
> > > Hesham
> >
> > Hello,
> > I think that it is rather simple task. Could you send me a testing file? i'll tryto manage it.
> > Mira
> Thank you Mira,
> Here is a link to a sample file:
> http://tinyurl.com/cr8csy
> H

Hello Hesham,
As soon as I saw a plot of your data, I've got to know that my first statement above was wrong. I have thought that you are measuring some "normal" material, but seeing the terrible behaviour of the measured object, I've to withdraw my declaration.
By the way, is it reasonable to speak about a yielding point, when there are so many "yielding" points within a test? (More over, you need to know also a length of a specimen, if deformation is known in mm, not in percents.) There are so many dislocations on the line. Maybe that instead of trying to find a parallel to the initial line, which is a curve instead of straight line, it would be better to calculate Young's modulus from a set of dislocation lines (?).
Sorry, Hesham, I am not able to give you better answer.
Mira

"Miroslav Balda" <miroslav.nospam@balda.cz> wrote in message <glbvbu$ltj$1@fred.mathworks.com>...
> "Hesham" <heltaher.nospam@mathworks.com> wrote in message <glave2$qob$1@fred.mathworks.com>...
> > "Miroslav Balda" <miroslav.nospam@balda.cz> wrote in message <glai85$2it$1@fred.mathworks.com>...
> > > "Hesham" <heltaher.nospam@mathworks.com> wrote in message <glac7l$nh8$1@fred.mathworks.com>...
> > > > Hello everyone,
> > > > I have many results of a tensile test, the data are x & y columns; x is strain and y is stress.
> > > > To calculate the Yield strength, I need to plot the data and at x=0.2% draw a line parallel to the initial line.
> > > > Since, I have too many files, I was wondering if someone know a way to automate this process.
> > > > Thanks,
> > > > Hesham
> > >
> > > Hello,
> > > I think that it is rather simple task. Could you send me a testing file? i'll tryto manage it.
> > > Mira
> > Thank you Mira,
> > Here is a link to a sample file:
> > http://tinyurl.com/cr8csy
> > H
>
> Hello Hesham,
> As soon as I saw a plot of your data, I've got to know that my first statement above was wrong. I have thought that you are measuring some "normal" material, but seeing the terrible behaviour of the measured object, I've to withdraw my declaration.
> By the way, is it reasonable to speak about a yielding point, when there are so many "yielding" points within a test? (More over, you need to know also a length of a specimen, if deformation is known in mm, not in percents.) There are so many dislocations on the line. Maybe that instead of trying to find a parallel to the initial line, which is a curve instead of straight line, it would be better to calculate Young's modulus from a set of dislocation lines (?).
> Sorry, Hesham, I am not able to give you better answer.
> Mira
Thank you Mira for taking the time.
Best,
Hesham

Hi Hesham,

I have same doubt like you ..I want to find the yield strength in Matlab. by plotting a line parallel to stress strain curve at x= 0.2%.
if your doubt is cleared, tell me how you did
Looking forward for positive reply
Thanking you.

Regards,
Vidya Joshi
"Hesham" <heltaher.nospam@mathworks.com> wrote in message <glac7l$nh8$1@fred.mathworks.com>...
> Hello everyone,
> I have many results of a tensile test, the data are x & y columns; x is strain and y is stress.
> To calculate the Yield strength, I need to plot the data and at x=0.2% draw a line parallel to the initial line.
> Since, I have too many files, I was wondering if someone know a way to automate this process.
> Thanks,
> Hesham

hello,
I plotted the data but how to plot parallel line at x=0.2% to initial line

Regards,
"Vidya Joshi" <vidyadjoshi@gmail.com> wrote in message <i2p2jo$d5c$1@fred.mathworks.com>...
> Hi Hesham,
>
> I have same doubt like you ..I want to find the yield strength in Matlab. by plotting a line parallel to stress strain curve at x= 0.2%.
> if your doubt is cleared, tell me how you did
> Looking forward for positive reply
> Thanking you.
>
> Regards,
> Vidya Joshi
> "Hesham" <heltaher.nospam@mathworks.com> wrote in message <glac7l$nh8$1@fred.mathworks.com>...
> > Hello everyone,
> > I have many results of a tensile test, the data are x & y columns; x is strain and y is stress.
> > To calculate the Yield strength, I need to plot the data and at x=0.2% draw a line parallel to the initial line.
> > Since, I have too many files, I was wondering if someone know a way to automate this process.
> > Thanks,
> > Hesham