Understanding Failure Theories (Tresca, von Mises etc...)

Failure theories are used to predict when a material will fail due to static loading. They do this by comparing the stress state at a point with material properties that can be easily determined from testing, like the yield or ultimate strengths of the material determined from a uniaxial test.
In this video I cover some of the main theories for ductile and for brittle materials - Rankine (maximum principal stress theory), Tresca (maximum shear stress theory), von Mises (maximum distortion energy theory) as well as the Coulomb-Mohr and Modified Mohr theories.
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The Efficient Engineer is a channel aimed at mechanical and civil engineers. The mission is to simplify engineering concepts, one video at a time!
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[@leoads]

I'm strucutral engineer with 20+ years of experience, and I wish I had an explanation like that when I was learning.... Took me a lot of time to fully understand, and I'm still learning. Congrats, very good.

[@TheEfficientEngineer]

Appreciate it, thank you!

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I came here to write the exact same thing. The explanations around the failure criteria are excellent.

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Have you ever use this once since school?

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@@mrmadame28 yes, a little

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Actually they provided you to understand content of this video. But when we look at it from another angle, you are right. You shouldn't have learned new things about a topic that was finished studying decades ago.

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Paid to university doesn't mean the university has to read the book for you.

[@danguee1]

I'm a structural engineer in my early 60s. I have never seen or heard this subject explained better than this. Too often in text books, the text is written by experts who don't understand the need to explain this progressively from simple to complex - they just go for the final, complex solution straight off. And so, the subject matter starts somewhat impenetrable for many beginners....

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im a structural engineer too, same thoughts, spectacular video, great editing, sound, graphics, music, holy crap the whole presentation I couldn't believe my eyes

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They write the books intentionally incomprehensible!

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@@amersabitovic203 certainly seems like it. why do you say so?

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As you said you are a teacher . Can you answer my one question ? If the pressure of the fluid varies with depth assuming the density to be constant, should the temperature also increase with depth in a fluid? I think yes. See the atmosphere above us a good example of it.

[@robertbrown5129]

@@physicslover1950 there is no relation of variation of temperature with depth . Think about ocean water as its top layer has high temperature than the water in depth bcoz of solar radiation . As we goes in depth water has less exposer of solar radiation bcoz radiation can penetrate in water upto a depth . When it comes to earth Atmosphere the atmospheric layer near earth has high temperature bcoz of reflection of radiation from earth and then greenhouse gases like water vapour , CO2 do not allow them to escape which causes increase in temperature of earth near layer atmosphere

[@ShauriePvs]

@@physicslover1950 by the way atmosphere doesn't have uniform density... So you can't compare the almost uniform density scenario of water and highly varying density case of air

[@user-vi3pi9rf7w]

@@physicslover1950 that's a very vague question there are many factors to consider here, By basic definition temp is measure of thermal energy which in turn is in case of solids and liquids is oscillations and in gas degree of random motion. Even more important is the fact that these changes in density of liquids are negligible with depth almost 2-3% you are comparing two different fluids with each other. Air is way different than water. And in the first place how did you manage to think that way? That temp would increase if pressure or density increases?? State eqn, I assume like ideal gas eqn, then its not applicable for subcooled liquids and I could even argue that Bcz we move air so much near the surface of earth the temp of air is higher, you get the point. I'm not even talking about radiations Whatever keep thinking, it's a good thing.

[@physicslover1950]

@@user-vi3pi9rf7w Thanks for the motivation actully I got the answer 2 months ago that the temperature doesn't increase down with the increase of pressure because if the temperature increased then according to boyles law volume must increase and if the volume increased the density of the liquid becomes less than that on the surface which is a vogue and non sense statement 😅. Actually the density decreases as we go down . Pressure =(constant)(density)( temperature ) So in this case the increase in pressure is only due to the increase in density and an increase in density is due to the dcrease in volume . Recall again the equation PV = nRT Or PV= T When pressure increased with depth the volume decreased and temperature remained constant and wise versa. In case of earth the temperature increases down due to non uniform gravitational field. But in case of a swimming pool the gravitational field is nearly uniform.

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I remember when I do FEM analysis using a software, these failure theories are present at the handbook/users’ manual of the FEM software. It is very nice to see the interpretation of these theories here. You did a great job. Thank you.

[@BoZhaoengineering]

I would prefer you denote the stress component in matrix than presented in plane shape/circles. According to matrix theory, any stress exerting to micro cube must be linearly transformed to the new basis, presented by the matrix. It is just my opinion at this moment.

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Bo Zhao shut up dude

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can u send me the user manual

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@@jerin3710 what software are you using? During my school years I used Ansys, it's a decent FEA software. Find it in torrentz or google it. Usually, schools provide one, but it skips many steps.

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@@andresgaviria9559 Ansys is what we use professionally. Atleast in the aerospace industry

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In my 20 years experience I never heard a much clear explanation/presentation of these concepts. Great effort and very good job.

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I study structural engineering at the highest ranked (by MIT) engineering university in Europe, and you just explained this particular subject much more clearly and in 1/6 of the time that the lectures took.

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The graphics are amazing and really helped me understand why the yield surfaces look the way they do!!

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Wow, this is the first time that I can say without doubt you explained these failure theories, where they came from, and the differences between them far better than I was taught in college. Thank you very much for making these videos and I really give you props for your deep understanding of so many topics

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Thanks for this visual aid, I'm gonna be taking the FE (other disciplines) this August and I know learning this theory will help me a bunch.

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Yo soy mexicano y para mí es complicado leer los subtítulos y observar al mismo tiempo las imágenes y gráficos. :C Espero algún día tengas tus video con audio en versión español, créeme que mucha más gente te vería, y hasta tendrías el doble de suscriptores, espero lo tomes en cuenta. Tus videos son grandiosos!!, pero a nosotros nos cuesta el triple de tiempo entenderlos a la perfección. Saludos.

[@Guywiththetypewriter]

Can I make a suggestion? As a student, information like this is invaluable. But , for those wanting to look further into the topic, having references to where you got this knowledge from would be most helpful. :)

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[@patrykserkowski7564]

The true is that the first to develop the theory of stresses and strength was Maksymilian Tytus Hubert (1904), the second Richard Edler von Mises (1913), the third was Heindrich Hencky (1924). James Clark Maxwell (1865) - main assumptions in letter. Eugenio Baltrami (1885) - concept. So, in the foto should be Huber or each one of them 😌

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I really loved your work. What book would you recommend for learning the significance and particular case for the appliance of the theories for a beginner in the field of structural engineering

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Mechanics of Materials - Ansel C. Ugural is an excellent book and has practical case studies on several applications

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I am starting my Masters in Solid Mechanics / Materials for stress state dependent failure of ductile metals, and I could not be more grateful for your solid mechanics videos. Thank you!

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Only channel till date that has wonderful visuals of complex mechanics concepts. Thank you for such amazing content.

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I've just invated all my students to come see your videos.

[@TheEfficientEngineer]

Thanks! :)

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Awesome videos sir thank you so much for this Can you please suggest reference book for learning mechanics of materials for mechanical engineering , i want to develop concepts like you . Thank you in advance sir 😊

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This is such beautifully done video on failure theories,It almost made teared up. Thank you so much. Same as others here in the comments section,we cannot thank you enough.

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As a Structural Engineer, your channel is fast becoming the main source of my CPD. I learn way more important stuff from it than formal sources that I can report PDH for.

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Me clicking on this video: "I have a degree in physics, whatever it is, I'll understand it." Me after watching the video: "There is nothing about this I understand."

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You're just being screwed by jargon. Abstract reasoning-wise, there's nothing that's demanding in structural engineering comparable to physics.

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@@passerby4507 I definitely would be aided by understanding the terminology. The math didn't seem overly complex, but the stress/strain "phase space" things seemed really cool.

[@willj78]

Where was this a month ago, my professor didn't teach it anywhere near this well!

[@msdesf]

The most comprehensive and understandable explanation of all time. Thanks a lot!

[@sanchitagarwal3471]

By far the best explanation of the failure theories that I have seen. Made my life a lot simpler.

[@vishnuraj6227]

Sir, can you do a video on Margin of Safety and its significance

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Simply beautiful. Great work summarizing an entire Machine Element Design course in Mechanical Engineering into a few minutes!

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Thank you for such an intuitive explanation. I can have the first impression of what these definition is. Good luck and stay safe!

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Engineering society needs more people like you. Keep the good works going on. Thank you. ❤

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Best out of best material is provided. Thanks for giving such an immense knowledge and fascinating video.

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One of the best educational videos I've came across in a long time. You got yourself a new subscriber.

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This is the best explanation of failure theories I have come across till now!! Thank you very much!

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I am an instructor on Solid Mechanics and definitely will recommend it to my students. Superb graphical details, congratulations on the job done

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Great work. Binch watching your channel now. Came for a reminder of the stuff I learned many years ago. Stayed for high quality content. I subscribed and I am looking forward to more content.

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You are really great sir... I couldn't able to imagine how the failure theory's are working. But you video made it easy for everyone... keep doing such works..

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You've just summed up 6 University courses and over half a year of my life in just over 15 min, I'm not sure if I'm happy or frustrated about this but A+ on your efforts 👍

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The concepts which take hours to digest has been precipitated nicely and explained in a matter of minutes without compromising the continuity / depth of the topic. The animations are intuitive. Have started making notes using your video. You channel will be a benchmark for all mechanical engineers. Suggest you to make and upload videos on Machine Design, Material Science, Thermodynamics and Fluid Mechanics. Hats Off to you!

[@paulbester1571]

Bloody hell bruh i sat through 2 lectures of this stuff and you explained it perfectly in 15 minutes. You are doing amazing work, please do keep it up.

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The way you guys have explained this is just phenomenal kudos

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Where have you been all my life. I'm watching all of your videos now, as this is the best explanation that made the codes and standards I'm using for work easy to assimilate. Thanks for this beautifully explained tutorial. I'll give anything to be a lifelong learner from you.

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