thecadguy
Automotive
- Apr 12, 2012
- 44
New to fatigue analysis and have a few fundamental questions of anyone would care to comment. Based on what I think I know is that a (S-N) stress based approach is best for high cycle fatigue and a (E-N) strain based approach for low cycle fatigue. The cut off generally being around 100K cycles.
Stress Based Approach
For high cycle fatigue I am using a (S-N) approach because the linear stresses are below 70% of yield and in the elastic part of the material curve. I clearly understand this no problem.
Strain Based Approach
When the linear stresses are over yield this is where I am still unclear and have questions.
1. Should I always use a strain based approach when the stress is over yield?
2. Should I use the above linear stresses, over yield, with an elastic plastic correction (Neuber).
3. Should I use non-linear stress results with no elastic plastic correction.
Any comments would be appreciated.
Stress Based Approach
For high cycle fatigue I am using a (S-N) approach because the linear stresses are below 70% of yield and in the elastic part of the material curve. I clearly understand this no problem.
Strain Based Approach
When the linear stresses are over yield this is where I am still unclear and have questions.
1. Should I always use a strain based approach when the stress is over yield?
2. Should I use the above linear stresses, over yield, with an elastic plastic correction (Neuber).
3. Should I use non-linear stress results with no elastic plastic correction.
Any comments would be appreciated.