That is not very easy to answer.
The maximum torque you can use depends on the size, the surface of the
material you are bolting together, thread type etc.
The easiset way to find it is to look in the manufactores catalogue, here is
an example, in Swedish though, but it should be understandable
http://www.bulten-stainless.se/teknisk_3.htm

If you look at the top "=C5tdragningsmoment Mv I Nm" recommended torque for
well oiled straight  surfaces.
Bumax109 is 10.9 =


"Brottkraft" is the force to break the bolt in kN
"G=E4ngstigning" is the thread pitch
"Str=E4ckkraft" is the force to stretch the bolt (making it longer) before =
it
breaks.

The sheer force depends on the bolt itself and the material you are bolting
together, although the bolt might take the sheer, it is not necessary that
the material will do.

You could probably use the formula for a rivet Ts=3DF/(n x (pi x d*d)/4)

Where Ts (tau-s) is the force in N/mm2, n number of surfaces, d is hole
diameter.

One more thing that complicates is the friction between the various
surfaces.


With best regards

Tomas Larsson
Sweden

Verus Amicus Est Tamquam Alter Idem

> -----Original Message-----
> From: piclist-bounces@mit.edu =

> [mailto:piclist-bounces@mit.edu] On Behalf Of Buehler, Martin
> Sent: Monday, January 30, 2006 12:33 PM
> To: Microcontroller discussion list - Public.
> Subject: [OT]: Mechanical Strength of a Bolt
> =

> =

> I need to know the strength of a bolt.
> =

> It is rated 10.9, so i think it's strength is 1000N/mm2 when =

> pulling it.
> =

> If i use this bolt to join 2 elements, which try to shift =

> against each other, how do i calculate the maximum force it can stand?
> =

>       ^
>       |  F
>       |
>      111
>      111
>      111222
>      111222
>      111222
>  BBBBBBBBBBBBBBB
>  BBBBBBBBBBBBBBB
>      111222
>      111222
>      111222
>         222
>         222
>         222
>          |
>          |  F
>          V
> =

> B =3D bolt
> 1 =3D element 1 pulling up
> 2 =3D element 2 pulling down
> F =3D maximum shearing foce it can stand
> =

> thanx!
> tino
> =

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