Fatigue - varying principal stress directions
Fatigue - varying principal stress directions
(OP)
Hi,
I'm looking for ways to calculate the fatigue life of a cast iron component which is subjected to several non-synchronized loads. The thing I find tricky is the fact that the directions of the principal axis varies significantly depending on the combination of active loads (I'm not even sure along which direction the cracks will form). How do I estimate the fatigue life in this and similar cases? Could you name any relevant methods or other references?
Thanks
/hpon
I'm looking for ways to calculate the fatigue life of a cast iron component which is subjected to several non-synchronized loads. The thing I find tricky is the fact that the directions of the principal axis varies significantly depending on the combination of active loads (I'm not even sure along which direction the cracks will form). How do I estimate the fatigue life in this and similar cases? Could you name any relevant methods or other references?
Thanks
/hpon
Regards,
hpon





RE: Fatigue - varying principal stress directions
Tata
RE: Fatigue - varying principal stress directions
I don't understand what you mean. Could you expand your explanation a bit?
The problem is not calculating the principal stresses. Instead, the problem is to estimate the cumulative fatigue damage caused by stress states which differ both in amplitude and orientation.
hpon
Regards,
hpon
RE: Fatigue - varying principal stress directions
Tata
RE: Fatigue - varying principal stress directions
www.Roshaz.com
RE: Fatigue - varying principal stress directions
Tata
RE: Fatigue - varying principal stress directions
(excerpt from mechanical design handbook)
h
RE: Fatigue - varying principal stress directions
How do you know that your method is accurate/conservative?
Do any of you have experience using Dang-Van's approach? Can you refer to any good texts about it?
/hpon
Regards,
hpon
RE: Fatigue - varying principal stress directions
Tata
RE: Fatigue - varying principal stress directions
In chapter 8 of Multiaxial Fatigue by Socie there is a review of some methods for nonproportional loading.
RE: Fatigue - varying principal stress directions
I am trying to understand you method. Do you proceed by calculating some equivalent stress measure based on DeltaSxx, DeltaSyy etc.?
What if you have three or more load cases?
(I cannot access crisb's link.)
/hpon (I hope that the "double-signature" is gone now)
RE: Fatigue - varying principal stress directions
Tata
RE: Fatigue - varying principal stress directions
How do you represent the mean stress?
/hpon
RE: Fatigue - varying principal stress directions
h
Tata
RE: Fatigue - varying principal stress directions