Well, the answer to the first question was simple.
The difference is that SW divides with pitch (n) instead of multiply in the automatic conversion.
So the formula should have been At = 0,7854 * [d - (0,9382 * p)]² to give M10 = 57,99 mm²
The question is what is right and what is wrong?
I will contact my VAR.
So, the formula in the help file is correct.
At = 0,7854 * [d - (0,9382 / n )]²
n = 1/p according to: http://help.solidworks.com/2013/English/SolidWorks/cworks/r_Tensile_Stress_Area_Bolt.htm
In the actual calculation they use n = p, so SW needs to modify this.
I have sent a mail to my VAR.
what is your reference for the equation?
it could just be 2 references
There was already a SPR on this issue. No 763671.
So just have to wait for an update.
what are the details of the spr?
Well, I can only see the problem description: "Formula used by SolidWorks Simulation to calculate the default bolt tensile stress area for metric threads is incorrect"
The correct formula is At = 0,7854 * [d - (0,9382 / n)]² where n = 1/p
But in the program, it is calculated like n = p. Maybe someone forgot a parenthesis in the formulation.
The result is that the tensile stress area calculated by the function is larger than it's supposed to be.