theorectical tensile area of botls under stress 2

hello, i am doing this project on the tensile area of bolts under stress and I wonder if anyone knows the reason for the often quoted formula ( average of pitch diameters etc) which was found by experiments done by E M slaughter in the 1930s..
it seems everyone quotes this relationship in finding the theorectical tensile area without saying why is it so..

does anyone know about this topic ( or good online refereces on this issue)


thanks

stanton_tan@hotmail.com

 

[CoryPad]

The authoritative work on this subject is contained within the following:

ISO 898-1
ISO 898-2
ISO 965-1
SAE 770420
VDI 2230

These are not available online for free, although you can obtain them from their publishers:

http://www.iso.ch

http://www.sae.org

http://www2.beuth.de/index_en.php3

Another source is FED-STD-H28/2B, available for free at:

http://astimage.daps.dla.mil/docimages/0001/34/77/H28-2B.PD9

(Thanks Kenneth for posting this numerous times in the past)

 

Another possible source for your project will be the Machinery's Handbook. Here, length of engagement is considered as well when determineing strength. I believe that most often, you will find tabulated values for tensile area will correspond very closely to the area calculated from minor diameter.

 

[poetix99]

Actually, what I saw in Machinery Handbook (a 20 year old edition) was a cross-sectional area that included the area of the thread that you would slice through if you started at the minor diameter and made a right angled cross-sectional cut. Seemed to be a nice little bit of attention to detail...

However I have pulled some 3/4-10 (B7 and B16) fastners to failure, in tensile tests and that thread is always "dangling" around like a hangnail. I think that, for a little bit of conservatism, you might consider using the actual minor diameter for tensile stress calculations.