dear sir, you are making those topics interesting as well as knowledgeable. this really makes me buy ur exergic videos. thank you for this question , it was really helpful. i
Sir , in nptel machine design pdf while explaining stress concentration they have done bit different. According to them , the ratio of max stress and nominal stress is termed as theoretical stress concentration factor but while using relation ,sigma max = sigma (1 +(2b/a)) , the mentioned sigma is stress that the body is subjected to without considering the hole condition ( no net cross section area condition ).Same way things have been explained in Shigley's mechanical engineering design book. Please guide as this way hole size wouldn't matter for calculating maximum stress generated due to hole .
Actually I have a doubt regarding nominal stress. Nominal Stress is the stress calculated on the basis of the net cross section of a specimen without taking into account the effect of geometric discontinuities such as holes, grooves, fillets, etc.But here we have taken into account the hole diameter.So can you please explain it.
I think that if the answer, 285 is exactly correct then the logic provided here is incorrect. Because in that case, large plate doesn't mean that d/w 0+) so that, nominal stress tenses to 95Mpa from its positive side (nominal stress --> 95Mpa +) and Kt tenses to 3 from its negetive side(Kt --> 0-) so that the maximum stress tenses to 285 Mpa from some side. I'm saying this because as per the graph it seems that the answer is 285MPa whenever d/w=0.1 . So, it is also not exactly 2.85 when d/w
Is it me or did he just multiplied stress with area to get stress again?! 🤔 The answer is 285, nominal stress is 95 and multiplied 3 is max stress. But second look he equated forces, but nominal stress flowing will still be 95 through out, there is no question of adding stress concentration if there is no change in the flow. Still confused 😕 please watch Jeff Hansons video on stress concentration on why I'm confused. Please explain stress concentration with this video, I know there is one done already, but with this to be clear please
Please refer to NPTEL PDFs as well where it is clearly mentioned which section to take. When hole area is less, they may take any section due to small difference. But correct way is explained in the video.
Sigma(not) is different than applied sigma. That is what I have told that all other institutes are doing mistake at. Please refer to any credible source to learn concepts :)
From graph for d/w=.05 K=2.85 so Smax=285 MPa Or Kt=3-(3.13d/w)+3.66(d/w)^2-1.53(d/w)^3 Kt=2.8524 Then Smax=285 MPa Or Kt=1+2(a/b)=>3. Since a=b (circular initially before load) t not given so for unit thickness Kt varies from .95 to 1 i.e Kt= 2.85 to 3 Then Smax=285 MPa Smax/Snom=Kt Snom= P/wt=P/(w-d)t
Thank you. This is very interesting. One can find more on www.fracturemechanics.org/hole.html Using empirical relation, \sigma_{max} happens to be nearly 285.1995 MPa
Thank u so much sir..... Thanks for concluding it, i believe 285 is the right answer.... But in karnataka pgcet mechanical 2017 paper the answer is 100 Mpa.....
sir I am afraid but your solution is wrong To obtain the maximum stress in a circular hole we need to multiply with applied stress only i.e. 95Mpa in this case I am saying so by taking reference from the book of Applied Elasticity by Martin.H.Shaad There in polar form of airy's stress function you can see this example page no 177 of 2nd edition
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In made easy solutions they have given answer as 190 MPa without even discussing anything about Stress Concentration Factor
dear sir,
you are making those topics interesting as well as knowledgeable.
this really makes me buy ur exergic videos.
thank you for this question , it was really helpful.
i
Thanx sir
I just have debate this by others for options b and c
And I m also getting c
But you have fully opened the concept. Thanx again
The problem is interesting because when the plate is large, d/w
Very interesting way to explain plz further bring this type of question
Thank you so much for delivering classes in English .... excellent quality contents.
Sir, we can find the exact answer by theory of elasticity formula for circle discontinuity , we prefer for lecture stress concentration nptl
U cleared it in a lucid way sir..
Simply amazing! Thanks a lot.🙏💕
At the point of 0 shear force ...we get maximum bending moment or bm can be either maximum or minimum
He is so cute 😬
Tharak apni jagah, parai apni
Thank you sir 💙💙💙
Sir , in nptel machine design pdf while explaining stress concentration they have done bit different. According to them , the ratio of max stress and nominal stress is termed as theoretical stress concentration factor but while using relation ,sigma max = sigma (1 +(2b/a)) , the mentioned sigma is stress that the body is subjected to without considering the hole condition ( no net cross section area condition ).Same way things have been explained in Shigley's mechanical engineering design book.
Please guide as this way hole size wouldn't matter for calculating maximum stress generated due to hole .
Please refer more lessons and solved examples in both the sources you mentioned. It will be clear to you.
Perfect explanation,,,
Amazing
mind blown...*ucking genius...thanks for sharing free stuffs ... please share more please 😍😍😍
Wow the explanation is so good and nice
Actually I have a doubt regarding nominal stress. Nominal Stress is the stress calculated on the basis of the net cross section of a specimen without taking into account the effect of geometric discontinuities such as holes, grooves, fillets, etc.But here we have taken into account the hole diameter.So can you please explain it.
This one was very interesting. Thank you for uploading it..:D
I am wondering that how many geniuses has actually solved that question at that time
Back then gate was held with data book
Questions like these are the sole reason why most aspirants lose faith in gate exam.
Thank u sir for this, I have also done mistake of multipling 3.
Please upload some other confusing questions like this.
Thank you very much sir
In brittle materials stress concentration at tip of the crack is??
Thank you sir.
Sir in ductile material stress concentration factor not much affect .can we consider as nominal stress as answer(190)
I think that if the answer, 285 is exactly correct then the logic provided here is incorrect. Because in that case, large plate doesn't mean that d/w 0+) so that, nominal stress tenses to 95Mpa from its positive side (nominal stress --> 95Mpa +) and Kt tenses to 3 from its negetive side(Kt --> 0-) so that the maximum stress tenses to 285 Mpa from some side. I'm saying this because as per the graph it seems that the answer is 285MPa whenever d/w=0.1 . So, it is also not exactly 2.85 when d/w
Hi sir..Kt can be ignored for ductile material under static load..
What happens if we did not consider stress concentration factor?
We will get wrong answer bro
Thank u sir. U r Making mechanical engineering more interesting. Respect sir
In the book of made easy , they give the answer 190mpa...
Helpful
Is it me or did he just multiplied stress with area to get stress again?! 🤔 The answer is 285, nominal stress is 95 and multiplied 3 is max stress. But second look he equated forces, but nominal stress flowing will still be 95 through out, there is no question of adding stress concentration if there is no change in the flow. Still confused 😕 please watch Jeff Hansons video on stress concentration on why I'm confused. Please explain stress concentration with this video, I know there is one done already, but with this to be clear please
IN NPTEL LECTURE BY PROFESSOR RAJESH PRASAD THEY CONSIDERED SIGMANOT AS EXTERNAL APPLIED STRESS
Please refer to NPTEL PDFs as well where it is clearly mentioned which section to take.
When hole area is less, they may take any section due to small difference. But correct way is explained in the video.
Chapter wise videos kaha milenge,, full lecture
You can visit EXERGIC website for all course details. For any further queries, you can call on 9536651816 or mail at support@exergic.in
Thank you.
Wow
Gr8
In case of 5 cm , what will be the answer??
Sir sigmanot ki vale aapne 95 Kyu nahi li aap sigmanot ki value nikal rhe hai
Sigma(not) is different than applied sigma. That is what I have told that all other institutes are doing mistake at.
Please refer to any credible source to learn concepts :)
Bhaiya nominal stress is known as maximum stress
From graph for d/w=.05 K=2.85 so Smax=285 MPa
Or
Kt=3-(3.13d/w)+3.66(d/w)^2-1.53(d/w)^3
Kt=2.8524
Then Smax=285 MPa
Or
Kt=1+2(a/b)=>3. Since a=b (circular initially before load)
t not given
so for unit thickness
Kt varies from .95 to 1
i.e Kt= 2.85 to 3
Then Smax=285 MPa
Smax/Snom=Kt
Snom= P/wt=P/(w-d)t
@EXERGIC SIR WHAT IS Kt?? Can you help me with that
Thank you. This is very interesting. One can find more on
www.fracturemechanics.org/hole.html
Using empirical relation, \sigma_{max} happens to be nearly 285.1995 MPa
This question I believe was put there to make mistakes.
i am the first viewer😀
kt=2.85
Thank u so much sir.....
Thanks for concluding it, i believe 285 is the right answer....
But in karnataka pgcet mechanical 2017 paper the answer is 100 Mpa.....
,,👍👍
Sir then In this case ,The correct ans is indeterminate as the answer is not matching
Last viewer🤸🤸
sir I am afraid but your solution is wrong
To obtain the maximum stress in a circular hole we need to multiply with applied stress only i.e. 95Mpa in this case
I am saying so by taking reference from the book of Applied Elasticity by Martin.H.Shaad
There in polar form of airy's stress function you can see this example page no 177 of 2nd edition
As far as GATE is concerned, in case of any contradiction or confusion always go with NPTEL. The solution done by us can be verified from NPTEL.
I don't know I should be happy or sad after seeing this question.
🤣🤣🤣