Stress Analysis II: L-03 Fatigue - Overview of Approach

[@sotirpopov3533]

Very Good, thank you Todd for the presentation. I still think Fatigue and DTA are not well understood and more training and discussion about this phenomenon is a key!

[@ToddCoburn]

Thanks Sotir! I will be adding more videos on these topics in the future. Feel free to reach out if you have questions, comments or suggestions.

[@sotirpopov3533]

...for sure, thank you Todd, getting deeper into DTA and AFGROW and trying to maintain my currency and increase my knowledge in these topics.

[@prithvinayak8443]

Hey Todd, At 33:42 , you’ve shown the answer for the Se of aluminium to be 32ksi but in the alternate lecture (L-03b) you’ve shown the table of Max Se’ and it says the value of that for Al in 19 and therefore in that lecture you’ve shown the answer to that problem to be 19ksi.

[@ToddCoburn]

There are two principles at play here. First, we set Se’ as 0.4 Ftu for Al, which indicates 32 Ksi for some aluminums. Next, you cut off the value to a maximum of 19 ksi. This is Se’, and overrides the first value. Following that, you apply Marin Factors to convert this pristine, perfect value to a more realistic one for your application.

[@hamidrezajavidrad4234]

Well-explained

[@ToddCoburn]

Thanks! Enjoy.

[@CDaeda]

In the stress World when they say matrix elaborate meaning? Application?

[@ToddCoburn]

Not sure if i understand your question. You can see examples of matrices and their usage and application in my Composite and FEA playlists. See if that answers your question.

[@critta603]

at 28:12 to find a and b do we use S'e or just Se?

[@critta603]

also the graph in the book on page 3-7 only shows low cycle fatigue calculation how would we find the failure strength fraction of a high cycle?

[@ToddCoburn]

James, always use Se. Se’ is an unadjusted preliminary “perfect” value. Of course, when you have limited information about the part or loading, as in some classroom problems, Se’ may be your best estimate for Se.

[@ToddCoburn]

The strength fraction f is based on Ftu and material only. Same value is used for low & high cycle fatigue calcs.