fatigue-sizing a shaft subject to torsion
fatigue-sizing a shaft subject to torsion
(OP)
Hello
Which equivalent stress should I use for fatigue calculations on a shaft subject to pure torsion?
Von Mises and Maximum principal differ significantly in this case and give hugely different fatigue lifes.
Thanks
Gio1






RE: fatigue-sizing a shaft subject to torsion
If you want to be on the safe side go with the shorter life.
Chris
"In this house, we obey the laws of thermodynamics." Homer Simpson
RE: fatigue-sizing a shaft subject to torsion
i'd use principal, but then Petersen bases his Kt on shear stress = T*16/(pi*d^3), refer fig 79, pg 105. but then in this case principal = shear, no?
RE: fatigue-sizing a shaft subject to torsion
rb1957
Yes this topic has moved to the FEA section, sorry.
Your point is interesting, if Petersen used max principal for Kt then it must apply for fatigue
(Kt is the concentration factor for fatigue, right?)
Thanks
Gio1
RE: fatigue-sizing a shaft subject to torsion
Sorry, I think the concentration factor in fatigue is Kf...
RE: fatigue-sizing a shaft subject to torsion