Torsion test simulation

svishal03

Hi all,

I am simulating torsion tests (after being successful with tension and compression tests). For tension and compression, I got a good comparsion with experimental and behaviour in tension is same as in compression (of course leaving the necking part).

For torsion tests, I have taken equivalent tensile stress = shear stress*sqrt(3) and equivalent tensile strain as = shear strain / sqrt (3).

This is based on Von Mises criteria.

But I have a problem, doing this I find that there is a variation of about 6-8 % from the uniaxial tension test and compression test . IS there some approxiamtion in Von Mises criteria of equivalent tensile stress and strain?

I tried to google and more and this what I found:


http://books.google.co.in/books?id=F...strain&f=false



From this ; am I correct below (you can read the abstractabove as well):

“Torsion equivalent stresses obtained using Von Misesrelationship (as I have done) are 6.5% lower than those obtained using BishopHill formulation which is more accurate”

So, can we say that torsion equivalent stresses will bearound 6.5% less than that obtained using uniaxial tension ?

Warm regards,

Vishal

svishal03

Please can anyone help?