You're a lifesaver. I'm a mechanical engineering student in Finland and I didn't quite understand the function of this method when our lecturer tried to explain it to us. I understood it right away with this video. Thank you.
I am a Brazilian student doing a Master in engineering in France, this lecture is the best that I found on the internet about this subject! Thank you so much!
Normally the professors I had on fatigue and fatigue analysis were so hard to follow or they would only copy formulas from their notes on the board from minute one till the end of the class! As if that was an improve your hand writing skills class! But this video is totally educational. Thank you prof.
By mirrored signal, do you mean repeating it back to largest peak? If so, no, since for unclosed loops the damage is usually taken to be one-half the closed loop damage. If you mean something else, let me know. But I don't think any method of artificially closing unclosed loops and counting half damage would be like any other technique.
Thank you very much for the lecture. From this video and the following two, I did not see any description regarding the difference between half cycle and full cycle. Could you explain a little bit on this issue? Thank you.
Hi Xiaohu Zhang, a half cycle is called a reversal. Two reversals make one cycle. The only consistent method for variable amplitude loading to determine reversals, is to determine the number of cycles and multiply by two. I hope that helps!
@@arcsaber1127 The only way to identify the cycle is the formation of a complete closed loop so there is no need to do anything with other reversals*. *The exception being for cases in which your time history does not start/end with the highest event in the time history; in this case you can get a residual--the damage in this case is calculated by closing all the remaining open loops and taking half-damage for the residual.
Excelent video. I have a question, at 13:15 why is the strain at point C smaller than at the point B ? If the Tension at C is higher than B's the strain should also be higher, right ?
at min 11:40 whs is is the stress at c on the right negativ and on the left positiv? and why is at min 20:50 the part between G and F not fully marked red?
at 11:40, C should extend into the positive stress side on the hysteresis plot to be consistent with my time history. That said, this example is a sketch to illustrate the process and not a numerical calculation. Regarding 20:50, I don't remember why I used different colors.
Thank you for letting me know of the issue. I have attempted to disable it. I will check on it and may need to do some additional updates. If you need a particular file from there, please let me know.
Thank you very much for your fruitful lectures. Could you please give me your email address? Actually I am working on fatigue analysis of mooring line. I have already got load history. But i can't determine the number of cycles as i have several same stress levels in diagram. I would be grateful if you give me your email address. Thank you
You're a lifesaver. I'm a mechanical engineering student in Finland and I didn't quite understand the function of this method when our lecturer tried to explain it to us. I understood it right away with this video. Thank you.
Thanks--happy studies!
this lecture is gonna get me a degree thesis!! Thanks so much.
I am a Brazilian student doing a Master in engineering in France, this lecture is the best that I found on the internet about this subject! Thank you so much!
Thanks Michael--happy studies!
Normally the professors I had on fatigue and fatigue analysis were so hard to follow or they would only copy formulas from their notes on the board from minute one till the end of the class! As if that was an improve your hand writing skills class! But this video is totally educational. Thank you prof.
Thanks! Happy studies--
Thank you so much, a great lecture ! I finally understood the point of this method !
Does the method for closing the non closed hysteresis loops (from 15:) is equivalent to apply the rainflow counting to the mirrored signal ?
By mirrored signal, do you mean repeating it back to largest peak? If so, no, since for unclosed loops the damage is usually taken to be one-half the closed loop damage. If you mean something else, let me know. But I don't think any method of artificially closing unclosed loops and counting half damage would be like any other technique.
Thank you. Very clear.
Glad it was helpful!
Excellent lecture😉 thank you very much.
Thanks Sabina, happy studies--
Thank you very much for the lecture. From this video and the following two, I did not see any description regarding the difference between half cycle and full cycle. Could you explain a little bit on this issue? Thank you.
Hi Xiaohu Zhang, a half cycle is called a reversal. Two reversals make one cycle. The only consistent method for variable amplitude loading to determine reversals, is to determine the number of cycles and multiply by two. I hope that helps!
@@mbarkey.mechanics Thank you for your response. It really helps.
@@mbarkey.mechanics Do the reversals have to be of the same closed loop, or can be any reversals of the same stress range?
@@arcsaber1127 The only way to identify the cycle is the formation of a complete closed loop so there is no need to do anything with other reversals*. *The exception being for cases in which your time history does not start/end with the highest event in the time history; in this case you can get a residual--the damage in this case is calculated by closing all the remaining open loops and taking half-damage for the residual.
Thanks a lot !!!
Hi, thank you for explaining this. How did you calculate the mean of the hysteresis loops for the mean/range table?
When identifying the cycles, if you have the maximum and minimum value of the loop you can calculate the mean = (max+min)/2
@@mbarkey.mechanics I completely missed the obvious with that one! Thank you :)
Thank you for the video!
Excelent video. I have a question, at 13:15 why is the strain at point C smaller than at the point B ? If the Tension at C is higher than B's the strain should also be higher, right ?
My sketch isn't great. I am indeed trying to indicate point C on the hysteresis plot is a little to the right of point B on the hysteresis plot.
@@mbarkey.mechanics the problem is that point C has >0 stress, isn't it?
@@egrabovic3577 yes, the point C in the sketch should have been a little positive, but that does not matter to identifying the cycle.
in the From To Rainflow matrix i think from 75 to (-20) would be in another cell. if I am wrong would you please tell me
at min 11:40 whs is is the stress at c on the right negativ and on the left positiv?
and why is at min 20:50 the part between G and F not fully marked red?
at 11:40, C should extend into the positive stress side on the hysteresis plot to be consistent with my time history. That said, this example is a sketch to illustrate the process and not a numerical calculation. Regarding 20:50, I don't remember why I used different colors.
Excellent lecture
Thank you Satish.
@24:41, I think the 1st mark drawn in the matrix should be in a cell (100, -200) of FROM-TO RAINFLOW Matrix
Thank you Sachin Kumar.
Could you update a reCAPTCHA on your website? The is no possibility to register to forum
Thank you for letting me know of the issue. I have attempted to disable it. I will check on it and may need to do some additional updates. If you need a particular file from there, please let me know.
I think I have restored my forum now and the downloads. Let me know if there are any issues.
Would be more nice with a better mic. Too much noises in the background.
Thank you very much for your fruitful lectures. Could you please give me your email address? Actually I am working on fatigue analysis of mooring line. I have already got load history. But i can't determine the number of cycles as i have several same stress levels in diagram. I would be grateful if you give me your email address. Thank you