Fatigue crack growth and steady-state creep

0:00 variability in S-N curves and influence of frequency
3:16 benchmarks, striations, clamshell patterns from crack growth
5:07 Crack growth rates and cycles until failure derivation
15:02 example of cycles until failure
22:44 factors affecting fatigue life
24:00 thermal stresses
24:55 creep
29:31 accelerated testing, larson miller parameter

[@todoshka]

Great lecture!

[@TaylorSparks]

Glad to help!!

[@cookiemaria780]

I have read that for some alloys fatigue cracks can initiate even if there are no defects in the material, and regardless of how high the stress applied is. I read that they initiate at the surface due to dislocation motions which roughen up the surface forming micronotches, even when the stress is way below the yield strength.
How is this possible ? If i were to cyclically stress a defect free aluminium alloy with a smooth surface at like 10 MPa, how can cracks nucleate at the surface when the stress is so low? Why does the cyclical nature cause this odd phenomenon? This has been confusing me for quite some time.

[@PradhanaKurniawan]

where did the 1,159 come from?
thank you for the video and very helpful

[@fidansmaili6306]

Great Job!
did you explain behavior of the fatigue short crack propagation somewhere in your youtube videos because I cant find it?!

[@TaylorSparks]

Unfortunately I have not yet prepared a video on short crack growth.

[@hazemab-mx6bv]

great lecture thanks a lot
in 10:30 neutral logarithm (ln) should be log (base 10) to be Compatible with the adjacent figure??

[@TaylorSparks]

Nope. Ln works.

[@majedloubani3320]

how did you get da at minute 20? great lecture