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J
JXBWk14-Alexandrite
14-Alexandrite
February 5, 2021
Question

roarks ebook 6th edition: constant for case 17b correct?

  • February 5, 2021
  • 3 replies
  • 14007 views

To all

In mcad Roark's e-book 6th edition there is a worksheet to calculate the stress concentration (case 17b).

I just noted that the constants to calculate the values for C1, etc are different to the ones in the latest book (Petersons 3rd edition)

1. Am I correct?

2. I cannot find a 1974 copy 1st edition (I guess!)  which appear to be the reference used. Has anyone got access and could confirm?

3. Is it the same in the latest ebook which I think is based on Roark's 7th edition but as far as I can tell in the printed Roark's 7th edition the numbers are from the 1974 edition too

 

Thanks

Regards

    3 replies

    F
    Fred_Kohlhepp23-Emerald I
    23-Emerald I
    February 5, 2021

    My printed 4th edition doesn't have a case 17 . . . (jumps from 16 to 18,  ???)

     

    My previous experience with the Roark ebook (under the original Mathcad owners) was that it had been farmed out to an intern as a project so they could improve their Mathcad skills; the information was (mostly) correct but the programming was stilted, plots were usually vectors not functions even though functions were used to calculate the vector values.

    Given your choices I would choose (in preference order):

    1. Peterson
    2. Printed Roark
    3. your best guess
    4. Roark ebook.

    If you post your problem geometry (not just a table reference) I'll try to help further.

     

    Good Luck!

    J
    JXBWk14-AlexandriteAuthor
    14-Alexandrite
    February 5, 2021

    Thanks. I set-up the Kt calc as per Petersons 3rd edition and for my geometry I got 2.65. the formula in Roark's ebook gave me 2.64. So not going to lose sleep

    The geo is irrelevant (but thanks for the offer) I am more concerned about the factors and the discrepancy

     

    W
    Werner_E25-Diamond I
    25-Diamond I
    February 5, 2021

    Not my area of expertise at all, but the table in the seventh edition I found here

    http://materiales.azc.uam.mx/gjl/Clases/MA10_I/Roark%27s%20formulas%20for%20stress%20and%20strain.pdf

    seems to correspond with the formula in the Mathcad sheet:

    Werner_E_0-1612534928294.png

     

      J
      JXBWk14-AlexandriteAuthor
      14-Alexandrite
      February 5, 2021

      but as fas as I can see the constants in the calculation of the C values are not the one in Peterson 3rd edition

      V
      VladimirN24-Ruby III
      24-Ruby III
      February 5, 2021

      7th Edition:

       

      7th Edition.png

       

      8th Edition:

       

      8th Edition.png

       

      P.S. Years of edition (from 9-th to 1-st): 2020, 2012, 2002, 1989, 1975, 1965, 1954, 1943, 1938.

      J
      JBlackhole16-Pearl
      16-Pearl
      February 6, 2021

      as per the original poster question I had a look at my copy of Petersons and indeed it seems that the constants defined in the C values are different - see attached Chart 3.10 from Peterson

      The Roark's data seems to be pointing to the 1st edition of Peterson

       

      @JXBWk The difference appears to be academic in this case - see graph attached (an "issue" at t/r = 2.0 possibly but I may have a made a mistake in typing the numbers!) but I get your point. One difference also is that the 1st set of C values are for 0.1 <= t/r <= 2.0 where in Roark's it is for 0.25 <=t/r<= 2.0

        J
        JXBWk14-AlexandriteAuthor
        14-Alexandrite
        February 8, 2021

        Peterson's also gives an equation for Kt bending, eq 3.7 - taken from Tipton et All (see attached), but if I "code" it get an imaginary number out of it !!

        Tried with D = 200, d=100, r15 and I get 0.65+0.479i

        Obviously does make sense - What I am doing wrong?

         

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