Hi.

Just explored this feature that arrived with SW2014.

In many ways it's great, but there are some questions.

First of all, my "old" reference for using bolt connectors is https://forum.solidworks.com/community/solidworks_simulation/simulation/blog/2009/10/15/calculating-preload-for-bolt-connectors

If I try with a standard M10 bolt I would, following the tip above, put in: 57,99 mm² as Ats (tensile stress area).

Preload for a reusable connection would be specified to: 0,75*Ats*Sp 

So for a 8.8 grade bolt it would be: 0,75*57,99*600 = 26095 N

With automatic conversion i get Ats = 69,02 mm² and a preload of 6424 N

According to help file: http://help.solidworks.com/2014/English/WhatsNew/c_wn2014_automatic_conversion_fasteners.htm

Tensile area is At = 0.7854 * [d - (0.9382 / n)]2

Preload is calculated: FI = 0.75 x At x 0.20 Yield Strength

With the "old" reference you calculate Dts = Dn - 0,938194*p

So for M10: 10-0,938194*1,5 = 8,59 mm² => Ats 8,59*8,59*pi/4 = 57,99 mm²

If I look up tables for M10, 57,99 is the normal value.

So why not use it in the automatic conversion?

And why only use 20% of yield as a pre tension force?