Quick note: at 1:45, the units of modulus of elasticity are not Newtons as the video labels-they are force per area, which can be Newtons/ sq. meter, or pounds/ sq. inch. This is the same units as stress since you're dividing by strain, which strain is unitless.
Firstly, this is a really good physics video on the stress formula. What I like about the Stress Formula is how you can use it to do so many different things. Furthermore, in this video you can identify what number to use as the stress variable in the formula. Because I was using yeld tensile stress and after watching this video I am going to start using ultimate tensile stress. The whole formula is really simple as well (Force ÷ Stress variable = cross sectional Area). Table1 # Example: Ultimate Tensile Stress=250MPa Force = 50,000N = 5,098.6 kg *F/s = A* 50,000N ÷ 250,000,000Pa = 0.0002m² = 2cm² Therefore, if you have a 2cm² rod of 250MPa steel it will rip with 5 tonne of weight hanging off it.
It is great that you are interested in deepening your knowledge about solid mechanics. In what kind of application do you require to calculate the stress of a material? It is important to consider that yield stress is usually prefered do to warranty the reversibility of the strain, as well as the minimum distortion of the loaded component, otherwise, ultimate stress would be the best choice.
Most simple way, easy to understand and with excellent clarity. Appreciated. Pls make video on optimum steam pipe sizing for saturated steam and condensate calculation.
Thanks for the video. One question, In order to get the Poisson Ratio and Youngs Modulus which tests are conducted? Is is Brazilian test, UCS test or Triaxial test?
The video indicates as "Perfectly plastic" the phase from point B to C, but that is not correct, as there should be no increment at all in the stress if the behavior were not just plastic, but perfectly plastic. Furthermore, it is not correct that the yielding "starts" at point B. The yield process starts at the end of the elastic phase, so in point A. For materials as the one shown in the video, which do not show a perfectly plastic behavior after point A (like common instead for hot-rolled steel) point B is often taken to get the characteristic value of the steel strength. In this case, point P is the point corresponding to 0.2% residual deformation and not just a casual point between A and C. It is also not a point that indicate the start or the end of the yielding phase, but just a conventional point to have a common and well defined way of obtaining the steel strength for design.
With increase in the stress beyond proportional limit from B to see there’s considerable increasing in this strain and there is no much increasing in this stress this is because of the plastic defamation in the metal this phenomenon called yield point
If a material is stretched between point A and B, and before plastic deformation begins, will it return to it's original shape? This question is really hard to find an answer to. Thanks.
If we keep up with the theory, any strain until point B is elastic, thus completely reversible, being the particularity of the region between A and B, that it is no longer linear, meaning it is a lot harder to be modeled. On the other hand, if we try to empirically verify all of this concepts, we will fail, because any real-world material has tolerances and manufacturing imperfections. This curves are gotten by exhausting experiments, statistics and modeling techniques. Due to all I have mentioned, the yield stress is usually chosen for a design, warranting not failure and minimum distortion of the components.
@@Larry-cp3uy Thanks to you for reading. Just for clarify a point, when I said that we will fail if we try to verify the curve, I didn't mean that the theory it is not true, but rather that it is very hard to get results as exact or precise as the theory suggests. Regarding the topic of yield strength for example (or any other point that seems to be perfectly defined in the curve), real-world materials tend to present such points as regions, meaning that is nearly imposible to perceive the exact moment when plastic strain begins.
The area is changing at different cross-sections. which stress is it talking about? the specimen breaks from the middle. so the stress is high in that area. you can see the area is changing drastically at that point. exactly which locations of the specimen the stress strain diagram represents and why?
Just as you have said, the diagram represents the central section where the rapid changes are seen. Probes are purposely design for concentrate the stress in the middle, otherwise failure and bigger distortions could present in other sections of the probe, thus rendering the test useless.
What do you mean by true stress and strain curve at the end of the video? I mean once you've reached the Ultimate tensile strength you basically do not need anymore stress/force/lead to deform it until it breaks... Meaning reaching UTS it'll only takes less stress for the necking to appear. Right?
When load is applied on the object it's area reduces continously. However we take initial area to calculate stress. Therefore, true stress is calculated using actual area.
I'm guessing then for true stress you would need to have worked out a model for area as a function of the tensile extension, say A(x) where x is the extension, then find its instantaneous change dA/dx. Then the true stress would just be given by: (Applied Force) ÷ (dA/dx) write? This would then be a stress function with independent variable being the extension of the material.
The strain is a function of the stress level, the time for which the stress is applied, and the temperature.Time-dependent strain under constant stress is known as creep
@@technoworks. I am a student Sir. I am studying Mechanical Engineering at IIT in India. Your videos are great. If you get time, then please make more videos Sir
The metal must be plastically deformed to permanently change shape, and this deformation creates dislocations which increase the strength.The formation of dislocations requires a stress greater than the yield strength to be applied to the metal.
@@technoworks. So the plastic deformation happening here seems to be of a different nature than the plastic deformation happening at later points in the curve. Where can I learn about the different types of plastic deformation happening? For instance, Maybe from A to B a bunch of crystals are being aligned or something, which leads to the hardening. And then the deformation at the last part may be just a matter of the cross-sectional area decreasing. I don't know. I'm just giving examples of what it might be.
![The Stress-Strain Curve EXPLAINED [for Ligaments & Tendons]](http://i.ytimg.com/vi/11qu6BX_jNg/mqdefault.jpg)
This is exactly what I wanted to see, to be able to relate the actual test and curve instantaneously. Thank You!
So. True... So damn true
Quick note: at 1:45, the units of modulus of elasticity are not Newtons as the video labels-they are force per area, which can be Newtons/ sq. meter, or pounds/ sq. inch. This is the same units as stress since you're dividing by strain, which strain is unitless.
You've nicely explained everything in less than 5 minutes!
Thanks😊
Only video that truly explains the stress -strain graph🔥
Nice presentation of the stress and strain curve.
This is the video I was searching!
Thanks for making this very simplified for us.
Firstly, this is a really good physics video on the stress formula. What I like about the Stress Formula is how you can use it to do so many different things. Furthermore, in this video you can identify what number to use as the stress variable in the formula. Because I was using yeld tensile stress and after watching this video I am going to start using ultimate tensile stress. The whole formula is really simple as well (Force ÷ Stress variable = cross sectional Area).
Table1 # Example:
Ultimate Tensile Stress=250MPa
Force = 50,000N = 5,098.6 kg
*F/s = A*
50,000N ÷ 250,000,000Pa = 0.0002m² = 2cm²
Therefore, if you have a 2cm² rod of 250MPa steel it will rip with 5 tonne of weight hanging off it.
It is great that you are interested in deepening your knowledge about solid mechanics.
In what kind of application do you require to calculate the stress of a material?
It is important to consider that yield stress is usually prefered do to warranty the reversibility of the strain, as well as the minimum distortion of the loaded component, otherwise, ultimate stress would be the best choice.
Best video about that I have ever seen
this helped a lot. Please make more videos in the future
sure. thanks
This video is packed with great information! A few funny grammar thangs but you know, doesn't really matter....unless you want it to.
finally understood stress-strain curve thanks
Great Video Applications that is well explained. Thank You!
T J (Tom) Vanderloop, Author, Education-Consultant & Certified Manufacturing Engineer
Most simple way, easy to understand and with excellent clarity. Appreciated. Pls make video on optimum steam pipe sizing for saturated steam and condensate calculation.
thanks, so helpful. Very good explanation
Entire 2 nd year preparation in 1 video thanks..
Fantastic videos
superbly explanation
Best for quick revision with the experiment loved it 👍👍👍
Glad you liked it
Thanks for the video. One question, In order to get the Poisson Ratio and Youngs Modulus which tests are conducted? Is is Brazilian test, UCS test or Triaxial test?
Good video.... you've earned yourself a like
Fully information and helped a lot, thanks
very well explained!! thanks
great explaination
I enjoyed this video, thanks mate ✌
Nice explanation
superb 😍🤩
Clearly Explained
💫✨🌟
by allah, one of the best
very good
Beautiful way of teaching 😘
will look like this *suggested videos block out graph*
other than that, good video :)
Very good 👍
Very helpful.. thank you so much .. i hope you add more like these
well explained. Thank so much
The video indicates as "Perfectly plastic" the phase from point B to C, but that is not correct, as there should be no increment at all in the stress if the behavior were not just plastic, but perfectly plastic. Furthermore, it is not correct that the yielding "starts" at point B. The yield process starts at the end of the elastic phase, so in point A. For materials as the one shown in the video, which do not show a perfectly plastic behavior after point A (like common instead for hot-rolled steel) point B is often taken to get the characteristic value of the steel strength. In this case, point P is the point corresponding to 0.2% residual deformation and not just a casual point between A and C. It is also not a point that indicate the start or the end of the yielding phase, but just a conventional point to have a common and well defined way of obtaining the steel strength for design.
Well explained
What size samples are needed for the tensile test
Solid 🪨 . I like the video
Wonderful explanation than most annoying talk creatures who talk more nonsens and less content
With increase in the stress beyond proportional limit from B to see there’s considerable increasing in this strain and there is no much increasing in this stress this is because of the plastic defamation in the metal this phenomenon called yield point
If a material is stretched between point A and B, and before plastic deformation begins, will it return to it's original shape? This question is really hard to find an answer to. Thanks.
If we keep up with the theory, any strain until point B is elastic, thus completely reversible, being the particularity of the region between A and B, that it is no longer linear, meaning it is a lot harder to be modeled.
On the other hand, if we try to empirically verify all of this concepts, we will fail, because any real-world material has tolerances and manufacturing imperfections. This curves are gotten by exhausting experiments, statistics and modeling techniques.
Due to all I have mentioned, the yield stress is usually chosen for a design, warranting not failure and minimum distortion of the components.
@@wolfvash22 Good explanation, thanks for the reply!
@@Larry-cp3uy Thanks to you for reading. Just for clarify a point, when I said that we will fail if we try to verify the curve, I didn't mean that the theory it is not true, but rather that it is very hard to get results as exact or precise as the theory suggests.
Regarding the topic of yield strength for example (or any other point that seems to be perfectly defined in the curve), real-world materials tend to present such points as regions, meaning that is nearly imposible to perceive the exact moment when plastic strain begins.
why do we have 2 different stress strain curves though? the true curve makes much more sense. why do we use the other one at all
👍👍
Thanks
I swear I'd never understood it before!
My old job at the steel plant. 👌
Naice
The area is changing at different cross-sections. which stress is it talking about? the specimen breaks from the middle. so the stress is high in that area. you can see the area is changing drastically at that point. exactly which locations of the specimen the stress strain diagram represents and why?
Just as you have said, the diagram represents the central section where the rapid changes are seen. Probes are purposely design for concentrate the stress in the middle, otherwise failure and bigger distortions could present in other sections of the probe, thus rendering the test useless.
What do you mean by true stress and strain curve at the end of the video? I mean once you've reached the Ultimate tensile strength you basically do not need anymore stress/force/lead to deform it until it breaks... Meaning reaching UTS it'll only takes less stress for the necking to appear. Right?
When load is applied on the object it's area reduces continously. However we take initial area to calculate stress. Therefore, true stress is calculated using actual area.
@@technoworks. how do you find the ultimate strength?
I'm guessing then for true stress you would need to have worked out a model for area as a function of the tensile extension, say A(x) where x is the extension, then find its instantaneous change dA/dx. Then the true stress would just be given by: (Applied Force) ÷ (dA/dx) write? This would then be a stress function with independent variable being the extension of the material.
SOK RAN SUB HAN....... ALLAAH.....@amin @ amen @ ameen........
Thank u
Love it
Does this depend in time?
The strain is a function of the stress level, the time for which the stress is applied, and the temperature.Time-dependent strain under constant stress is known as creep
What are advantages and disadvantages of tensile test
👍👍👍👍
Why you stopped making videos, please make more, you are great
Sir I started sharing experience during covid time. Now I hardly get any time to prepare video. I will definitely start again.
@@technoworks. I am a student Sir. I am studying Mechanical Engineering at IIT in India. Your videos are great. If you get time, then please make more videos Sir
Why stress in vertical axis ans strain horizontal axis? Have any physics behind this?
Strain is an independent variable that can be clearly observed. Meanwhile you cannot observe the stress directly, but only calculate with hookes law.
thanksss
area under O to B is the elastic region right?
Yes
Yes
@@technoworks. okay thank you! Another thing, does A to B still obey hooke's law?
@@kjca7890 no, there will be about 0.02 to 0.05% permanent deformation.
what happen to the substance when it reach the strain hardening point?
The metal must be plastically deformed to permanently change shape, and this deformation creates dislocations which increase the strength.The formation of dislocations requires a stress greater than the yield strength to be applied to the metal.
Is it possible to the neck form two or more in a piece?????
no
What about upper and lower yield point
What happens between A and B?
between A & B there will be plastic deformation. for more details watch this video ruclips.net/video/ayl_YQh8b_c/видео.html
@@technoworks. So the plastic deformation happening here seems to be of a different nature than the plastic deformation happening at later points in the curve. Where can I learn about the different types of plastic deformation happening? For instance, Maybe from A to B a bunch of crystals are being aligned or something, which leads to the hardening. And then the deformation at the last part may be just a matter of the cross-sectional area decreasing. I don't know. I'm just giving examples of what it might be.
الحمد لله
Where is Upper and lower yielding point??
SHOW ITS ON FUNDAMENTAL LEVEL OF UNIVERSE SO WE BWCOME MORE EASY TO HANDLE THE UNIVERSE
Please change d voice..otherwise d video is good.
👍
The tts engine sounds a lot like the subnautica pda
Where is the ultimate tensile strength at true stress curve?
Subnautica pda???
Alevels anyone?
ㅎㅇ
👍👍