Dear Sir, Last day I had an interview at IIT Jammu, Professor asked me why non-ferrous materials don't show a real endurance limit(Horizontal S-N Curve). I'd no answer, later I searched in Dieter but they had no reason for it. May I get some help?
True endure limit can be observed for high strength materials not only for steels. Crystal structures plays an important role in determinning this. For the case of non ferrous metals like Aluminium or copper (which are soft ) true fatigue life is not observed. Presence of more than 5 independent slip systems allows easy gliding. That's why continuous decrease in life with stable crack propogation can be observed.
the larger the better, for example single crystals are used in a jet engine where both the temperature is very high and they undergo high cycle fatigue as they are often going from turned off to rotating at a high speed. fatigue mainly happens by defects moving to grain boundaries, so if there are less grain boundaries fatigue is reduced
@@patrickcurran5536 thanks for your answer. I just want to ask one more thing . Are these defects that you are referring to, induce crack initation at grain boundaries ?? And is thermal fatigue always cause intergranular failure ?
@@ayay9835 defects are things such as dislocations, stacking faults, twin grain boundaries, but the defects such as dislocations coming together is what induces crack initiations at grain boundaries. Dislocations are small holes in the crystal if you put many small holes together you get a big hole or a crack. thermal fatigue i'm not sure, could possibly be related to dislocations moving and somewhat related to creep, but i'm not too sure what thermal fatigue is
Fatigue inherently involves the cycling of stress, therefore the stress amplitude is important. what S-N curve shows is that the higher the stress amplitude (S) lower is the fatigue life (N). But the variation of stress amplitude is done at constant mean stress, usually zero. But, the mean stress does affect fatigue life. Increasing the mean stress decreases the fatigue life. But this aspect is not captured in the S-N curve which is drawn at constant mean stress.
Couldn't ask for more ... No unnecessary talks .. .only to the point pure explanation ❤️
Thank you from Italy for posting this interesting video
Great explanation, thank you sir. I got to understand fatigue better
Helped me to score really good marks in my semester examination on Material Science and Engineering.
Very good source for students of other colleges
Thanks, Really good explanation and great examples.
Nicely explaination how about for rubber material is it the same
Many thanks sir for concept clear , east and best
but why does fatigue occurs? on microscopic levdl?
Ak number...
Thank you sir... you have been very helpful for my revision of concepts..
Tq sir
@@boinivenkatamma3427 à
Thank you sir from Bangladesh
neat explanation of all required concepts...
Sir, can you please arrange a class on radiation effect on TDBT..
thank you sir
Thanks sir
Dear Sir,
Last day I had an interview at IIT Jammu, Professor asked me why non-ferrous materials don't show a real endurance limit(Horizontal S-N Curve). I'd no answer, later I searched in Dieter but they had no reason for it. May I get some help?
True endure limit can be observed for high strength materials not only for steels.
Crystal structures plays an important role in determinning this. For the case of non ferrous metals like Aluminium or copper (which are soft ) true fatigue life is not observed. Presence of more than 5 independent slip systems allows easy gliding. That's why continuous decrease in life with stable crack propogation can be observed.
@@varaprasad6608 Please fix your spelling mistakes
Good Presentation!..But Take Care of the Signs in the equations(max and Min) which is negative?..
He did it right .it supposed to be that way.
Clarity from the root
sicklic loading?
🙏🙏
Sir does it come total under fatique failure sir just confirm it
I wish my collage professor are also same as you. Atleast handwriting should be
👍👍👍👍👍
Very
sir thank you sir, good video sir
me likey how indians pronounce "fatigueee"
Sir what should be the grain size to avoid high temperature fatigue ??
the larger the better, for example single crystals are used in a jet engine where both the temperature is very high and they undergo high cycle fatigue as they are often going from turned off to rotating at a high speed.
fatigue mainly happens by defects moving to grain boundaries, so if there are less grain boundaries fatigue is reduced
^^ for the turbine blades
@@patrickcurran5536 thanks for your answer. I just want to ask one more thing . Are these defects that you are referring to, induce crack initation at grain boundaries ?? And is thermal fatigue always cause intergranular failure ?
@@ayay9835 defects are things such as dislocations, stacking faults, twin grain boundaries, but the defects such as dislocations coming together is what induces crack initiations at grain boundaries. Dislocations are small holes in the crystal if you put many small holes together you get a big hole or a crack.
thermal fatigue i'm not sure, could possibly be related to dislocations moving and somewhat related to creep, but i'm not too sure what thermal fatigue is
Thanks u very much sir.
Sir why stress amplitude is taken in S-N curve why not mean stress??
Fatigue inherently involves the cycling of stress, therefore the stress amplitude is important. what S-N curve shows is that the higher the stress amplitude (S) lower is the fatigue life (N). But the variation of stress amplitude is done at constant mean stress, usually zero. But, the mean stress does affect fatigue life. Increasing the mean stress decreases the fatigue life. But this aspect is not captured in the S-N curve which is drawn at constant mean stress.
What is no of cycle to failure
10^6 cycles
0:19
?
He probably refers to the fact how you pronounced shy-click loading as sick-lick loading !
ghanta bhi nhi smjhaya...isse 10x better book me diya h
Han bhai mujhe bhi hindi me bataye to kuch samjh me aaye angrez ki aulaad
There are a lots of video on RUclips far better than this 😬
Slow teaching
Learning needs time
It's not a pill
2X PE DEKH LE BHAI
Generic cookie cutter explanation of fatigue basically offering no extra insight than what's available in your typical textbook