Notes on Fitted Curves and Calculators in fatigue database

PowderSteel Example Raw File __ | __ Fitted __ | __ Calculator

Typically in such a line there are 3 links. The html code behind the
lines can be seen by doing a "View Source" option in your browser.
(In Firefox click the Right Mouse button in the viewing area)
The contents of such links are, for example:

• "PowderSteel Example Raw File"
  links to a file q1001PM-0.45C-Chernenkoff.html
  This file is usually a "raw" fatigue test data file set into the
  SAE Standard fatigue data file format and then surrounded with
  a "wrapper" of HTML code that presents it as a viewable html file.
  If you Click on this Example Raw File
  and use the "View Source" technique in the browser, you will
  see how the file is constructed.
  

  When you select one of the radio buttons at the top of the browser page:

  
  
  and click on the Send for Processing button, the text
  contained in the box below the buttons will be transmitted to
  the U.of Waterloo website for processing. You can make changes to
  the text box contents. One can delete a fatigue data point by
  placing a "#" in the first position of a data line; or one can
  add a bunch of new data lines, and then re-transmit the file.
  Go ahead and try it.
  
  After the transmitted file is processed at the remote site,
  a graph and some text are returned to your browser.

  
  
  Towards the bottom of the returned page you will see a section of
  text that constitutes the "traditional" Coffin-Manson-Basquin fitted
  file. These fitted points are from the black and green lines that
  go through the data points in the above graph.

        
          # NOTE!! The Following Points are FITTED DATA:#NOTE!! Fitted Stress computed using Experm. K' and n'
          #Stress_Units= KSI
          # Total Strain   2Nf  Stress  Mean   Plastic Strain   Initial
          #    Amp               Amp   Stress      Amp        Elastic Mod.
             0.48820          1   181.8      0.   0.48204     29500. #Fitted_point
             0.31548          2   170.1      0.   0.30971     29500. #Fitted_point
             0.17795          5   155.8      0.   0.17267     29500. #Fitted_point
             0.11599         10   145.9      0.   0.11105     29500. #Fitted_point
             0.07609         20   136.5      0.   0.07146     29500. #Fitted_point
             0.04419         50   125.1      0.   0.03994     29500. #Fitted_point
             ....etc
  
  
  
          

• When one Clicks on the

                   __ | __ Fitted __ | __
  
           

  link of the database files, one will view a file similar to the raw
  data file, but with only the fitted data points taken from
  the text output from the processed raw file described above.
  

  Often the "traditional" fit method will not actually fit all
  parts of the raw data plot. Thus manual adjustments are made
  to the automatic fit output, to better model the characteristics
  of the raw data file. The Fitted data file can be processed
  using the same Send for Processing button, but the results do not
  really have any useful meaning. The file is just provided to
  users who may wish to adjust the fitted file for their own needs.
  
  
  

• A Click on the

                __ | __ Calculator
  
           

  will return a web page that contains the Fitted data file
  in the text box of the page. In order to use the calculator one
  can replace the sample values of the user elastic stress history
  at the bottom of the page and submit the page for processing by
  clicking on the Calculate button at the bottom of the page.
  

  One can also scale the cycle history entered by altering the
  magnification value (item #2 on the page), and re-submitting the page.