Dear Sir, thanks for the video. From min 10:45 to 10:50, it is explained that in "Completely Clamped Portion" there is "no internal or external force". I understand that at the extremities of the completely clamped portion the force P due to temperature variation is completely balanced by forces from sleepers in the breathing portion. So in a way the clamped portion may be thought upon a rod undergoing temperature change but restrained at both ends (an example given in this video earlier), therefore the deformation in the clamped portion is nil, but taking the same example, the stresses within the clamped portion are ought to develop, hence will it be correct to say that there is "no internal or external force" in clamped portion ?
Very good question. Look at it like this. The rail gets expanded (in its full length) whenever there is a rise in the rail temperature above the laying temperature. This expansion is in full length but you can see it only at ends of the rail. This movement (at ends) is permitted through switch expansion joints provided between two welded rails. And the total rail remains stress free. This is not like a rod which is constrained at both ends. Here rail movement is constrained by the friction between the rail and the sleeper. I hope it is clear now.
Respected sir please check at time 16:55 you take n=152 , and multiply by spacing but i think we have to take (n-1) here and multiple spacing please check once sir
No, it is taken n only, because rail hangs half of the spacing on both sides. Otherwise also, it will not make much difference whether you take n or n-1. Practically, it is same
Maybe It's not related with the video but it's about rails. Professor Chandra, About surface quality in a rail, What does mean a "hot mark" and a "cold mark" in a rail? thanks for answer
Hot mark is the depth of rolling guide marks anywhere on the rail. It should not exceed 0.5 mm and a max of 2 are allowed per rail. Cold mark is the longitudinal or transverse cold formed scratches formed anywhere on the rail surface. Limiting value here also is 0.5 mm
Secondly, sir please shed some light on the following: In the literature and IRC/IRS/IS codes, two types of temperature variation is defined - temperature gradient (across depth) and overall temperature change (along length). I understand that the video has well explained the overall temperature rise/fall (along length) issue. But how is the temperature gradient effect taken care of in rail design ? because I understand that between two sleepers, the rail must be hogging (bending upwards) due to temperature gradient effect !
This is not a serious issue (in my opinion). The reason - rail is a very good conductor of heat and there will hardly be any temperature gradient in vertical direction.
Sir apna number de dijiye ya phir ek question ka answer bata dijiye ncr pryj division engg (pway) exam me question aaya h. Question is In breathing length which of the following is true(1) free to move so no thermal force throughout B.L.(2) uniform force equal to half the force in Central portion (3) thermal force gradually increasing from SEJ to central portion (4) none of these. Sir vvip question please give answer which option is true
Breathing length by definition is the length at each end of an LWR that is subjected to expansion or contraction due to change in temperature. It means temperature stresses are set up in this portion of LWR which are slowly balanced by the resisting force between rail and sleeper. Therefore statement 3 is correct.
Very helpful video sir
Thanks, Keep watching
Other wise you have explained the LWR theory in very simple manner
Thanks
Glad to hear that
very good knowledge i got. thank you sir.
So nice of you, keep watching
Dear Sir, thanks for the video. From min 10:45 to 10:50, it is explained that in "Completely Clamped Portion" there is "no internal or external force". I understand that at the extremities of the completely clamped portion the force P due to temperature variation is completely balanced by forces from sleepers in the breathing portion. So in a way the clamped portion may be thought upon a rod undergoing temperature change but restrained at both ends (an example given in this video earlier), therefore the deformation in the clamped portion is nil, but taking the same example, the stresses within the clamped portion are ought to develop, hence will it be correct to say that there is "no internal or external force" in clamped portion ?
Very good question. Look at it like this. The rail gets expanded (in its full length) whenever there is a rise in the rail temperature above the laying temperature. This expansion is in full length but you can see it only at ends of the rail. This movement (at ends) is permitted through switch expansion joints provided between two welded rails. And the total rail remains stress free. This is not like a rod which is constrained at both ends. Here rail movement is constrained by the friction between the rail and the sleeper. I hope it is clear now.
Yes sir, it is clear. Thank you. If I may suggest, please cover the topic of "Rail Structure Interaction" in your videos.
Ok, will try, but that is not my area@@toffblade1
Nice explanation ,thank you sir
Keep watching, thanks for liking
Thanks a lot sir, very easy explanation 🎉
Thank you so much. Keep watching
Respected sir please check at time 16:55 you take n=152 , and multiply by spacing but i think we have to take (n-1) here and multiple spacing please check once sir
No, it is taken n only, because rail hangs half of the spacing on both sides. Otherwise also, it will not make much difference whether you take n or n-1. Practically, it is same
Precious knowledge.
I am track maintainer, many concepts are not clear.
Thank you❤
Can you suggest a topic for further discussion?
@@SatishIITR Please cover the topic of "Rail Structure Interaction" in your videos.
Thank you sir
You are welcome. I have covered almost all topics in Railway Engineering. See the playlist once
Min length of LWR is 250m as per IRPWM, overall video is nicely explained Sir...
Thank you so much.
Sir kindly make video on destressing of LWR by using rail tensor
Thanks for the suggestion
हिंदी में वीडीओ नहीं मिल सकता है क्या थ्योरी का
Maybe It's not related with the video but it's about rails. Professor Chandra, About surface quality in a rail, What does mean a "hot mark" and a "cold mark" in a rail? thanks for answer
Hot mark is the depth of rolling guide marks anywhere on the rail. It should not exceed 0.5 mm and a max of 2 are allowed per rail.
Cold mark is the longitudinal or transverse cold formed scratches formed anywhere on the rail surface. Limiting value here also is 0.5 mm
Thank you very much
Sir why LWR isolated from points & crossing but CWR continued?
I don't think there is any such limitation in the case of LWR.
Sir what is the primary objective of providing LWR ?
to reduce the number of fish plated joints and to reduce to maintenance cost
Sir calculation of P = 66.16x2x1000000x(1.152/100000)=1.636 ?
in my calculation it comes 1524.326
?
Do not worry about the values. learn the concept. Your calculation is correct.
Secondly, sir please shed some light on the following: In the literature and IRC/IRS/IS codes, two types of temperature variation is defined - temperature gradient (across depth) and overall temperature change (along length). I understand that the video has well explained the overall temperature rise/fall (along length) issue. But how is the temperature gradient effect taken care of in rail design ? because I understand that between two sleepers, the rail must be hogging (bending upwards) due to temperature gradient effect !
This is not a serious issue (in my opinion). The reason - rail is a very good conductor of heat and there will hardly be any temperature gradient in vertical direction.
ok, I follow now sir. Thank you.
Thanks @@toffblade1
What is the distance between 2 LWR ?
they can be laid on after another with swicth Expansion Joint.
Sir apna number de dijiye ya phir ek question ka answer bata dijiye ncr pryj division engg (pway) exam me question aaya h. Question is In breathing length which of the following is true(1) free to move so no thermal force throughout B.L.(2) uniform force equal to half the force in Central portion (3) thermal force gradually increasing from SEJ to central portion (4) none of these. Sir vvip question please give answer which option is true
Breathing length by definition is the length at each end of an LWR that is subjected to expansion or contraction due to change in temperature. It means temperature stresses are set up in this portion of LWR which are slowly balanced by the resisting force between rail and sleeper.
Therefore statement 3 is correct.