Hi guys,

 

I'm writing a lab report on fatigue testing and have been asked to discuss methods of predicting fatigue failure. After researching this I came across a method called E-N curves, which we haven't covered in our class (we're using S-N curves) so I was wondering if anyone can explain E-N curves to me simply? Thanks!

Hi guys,

 

I'm writing a lab report on fatigue testing and have been asked to discuss methods of predicting fatigue failure. After researching this I came across a method called E-N curves, which we haven't covered in our class (we're using S-N curves) so I was wondering if anyone can explain E-N curves to me simply? Thanks!

 

 

Hi,

E-N curves refer to strain life (from strain = epsilon = "e"), and is mostly used for low-cycle fatigue, i.e. for high loads that lead to more rapid failure. S-N curves are applicable for high cycle fatigue, when nr of cycles exceeds 100,000 or so. Check out this website.

Hey, thanks for the reply. I actually have seen that website already, I understand that they're strain-life curves, what I wanted to know was if there's a simple explaination of how they're created? The theory seems fairly complicated if you've never covered it. We have to draw an S-N curve so I understand the theory for that (basically what is the lab procedure to draw an E-N curve?), are the two similar?

 

Thanks!

Edited February 24, 201213 yr by VelocityGirl

I have no idea where you are in your education but I find papers like the following helpful in gaining the knowledge I require:

 

Mean Stress Effects in Strain–Life Fatigue by N. E. DOWLING

 

This one builds up through application and specialization.

I'm in my final year of an ordinary degree in mechanical engineering. Thanks for the help guys, ended up just writing what I could for it in terms of how much I understood. I didn't need to go really in depth but it'd have been nice if the lecturer would've covered it with us to save any confusion!