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Recent content by AJohnson

  1. AJohnson

    Cut threads vs rolled threads

    R.E. Peterson has a book entitled "Stress Concentration Factors" that has a detailed discussion of the parameters that derive Kf, as well as values that you can use. Joseph Shigley's text "Mechanical Engineering Design" also has values you can use. Andy
  2. AJohnson

    bolt stress concentration factors

    LeeEccles, One additional comment about stress concentration. You mentioned a value of 3 for the threads. In my recent experience, I have found that to be a good value when using rolled threads. I have found many references that use values from 4 to as high as 12 for cut or ground...
  3. AJohnson

    CVN Impact Test

    ASM handbook Volume 8, Mechanical Testing, has a good history section on how CVN testing came into being, its limitations, and most importantly, its overall purpose, which is to define the temperature range of transition from ductile-to-brittle fracture. These two sentences seem particularly...
  4. AJohnson

    Makes you feel good to be an Engineer . . .

    Nice quote; however, I haven't seen too many buildings covered with vines or trees. I think he was a little off the mark their. Maybe in Hoover's day hiding poor architecture with vines was common. Andy
  5. AJohnson

    Bolt Fatigue Life

    Juvinall and Marshek (1991 text) and Shigley and Mischke (1989 text) use a similar approach for estimating S-N curves of notched metals, based on tests conducted in smooth rotating members. The test result numbers are then adjusted for certain various factors such as: load type, member size...
  6. AJohnson

    Mil-Spec for Grade-8?

    Helpme01, MIL-DTL-1222 has grade 8 equivalent hex head bolts and nuts in it. If you want something stronger, look at FF-S-86, which has socket head cap screws. Both can be found at this link: http://assist.daps.dla.mil/quicksearch/ just type in 1222 or 86 in the number block and search the...
  7. AJohnson

    Calculation of Tensile Stress Area for Fasteners?

    Cory, et. al., Both the 12th and 20th editions of Machinery's Handbook have both equations...interesting that the one for steels >100 ksi ult. appears to have been removed from the 25th edition and then replaced in the 26th edition. A simple error perhaps? Also interesting is that...
  8. AJohnson

    Determination of Fracture Toughness

    Greg, Yes there are correlations, but there is not one simple one. There are different correlations for the upper shelf, the transition region, and the lower bound. I could list a few equations, but I feel they would be of no help without you reading all the background text that goes with...
  9. AJohnson

    rolled threads

    Here's some stuff I dug up...the short and sweet is rolled threads were patented in 1896, and so became prevalent sometime after that. Lathe cut threads have been around in various forms since around 1700. Here's the long version... Screw-Turning Lathes The screw, because of its many...
  10. AJohnson

    Shaft Coating in Marine Enviroment (inside&out)

    Hey Boo1, Take a look at electroslag surfacing. It's expensive, but works quite well. Andy
  11. AJohnson

    where to buy part for AMW mig welders (rectifier)

    These guys post capabilities for Miller and Lincoln machines. They might be able to do others or know of someone who can. http://www.industrialelectronics.com/ Andy
  12. AJohnson

    SA-515 vs. SA-516

    In a nutshell, yes. Both of these steels are pressure vessel carbon steels with similar chemical compositions. The 516 grades have carbon content maximums that are .02 to .04 % lower than the 515 grades. Carbon also happens to be one of the most potent alloying elements in its effect on...
  13. AJohnson

    friction factor

    Boo, I understand dynamic (kinetic) and breakaway (static). You still haven't addressed steel on steel with no lubricant friction factor being lower than steel on steel WITH lubricant. That can't be right...or else what is the purpose of lubricant?...to INCREASE friction?...I don't...
  14. AJohnson

    ALternative material

    Pablo, Do you really need the same range of hardness values?...or will equivalent yield and tensile strength suffice? Do you still want a precipitation hardened stainless steel that has been overaged? Are you looking to get a new material that has equivalent mechanical properties but has...
  15. AJohnson

    What material is "10B21" ?

    See SNo 19 at this link: http://www.steelexchangeindia.com/insidesteel/utilities/specforironst.htm Andy
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