Stress-Strain Relations: Tensile Testing, Yield & Ultimate Strengths, Elastic Modulus, Safety Factor

LECTURE 04
Playlist for ENGR220 (Statics & Mechanics of Materials):
• ENGR 220: Statics and ...
This lecture was recorded on September 13, 2019. All retainable rights are claimed by Michael Swanbom.
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Thank you for your support!

[@prabin1637]

I am planning to attend my lectures, watch your videos then do homework. Watching your videos before approaching Homework should really help me reduce hours of time I get lost while trying to solve it.

[@TheBomPE]

I'm glad it's helping! Best of luck in your studies!

[@raquelmariagarridorodrigue6088]

Hii!! Here a chemEng student from the south of Spain. Thanks to your lecture i really understand material science and love it. Greetings from Spain.

[@jadjawhar8977]

I wish you were our lecturer! So clear, great job. Looking forward for more videos of yours 😃

[@TheBomPE]

Glad you enjoy the videos! It's nice to think I'm helping people! All the best to you!

[@khaidirandromeda]

If all engineering lecturers around the world, especially in the third world country, can explain course material like him, we should be able to colonize Mars by now.

[@baviquevirechecantepuspace2615]

I live in a developed country, and still find very bad lecturers. I have learnt more from youtube than in any lecture. It just proves how bad the education system is.

[@SeattleCoorain]

Very, very clear explanation of otherwise difficult concepts to acquire in just a few sessions. Love the modern whiteboard presentation technique. I am a retired computer engineer trying to design prefab affordable housing (called Backyard Cottages in Seattle), using Sketchup-Pro and SkyCiv online stress analysis tools. I think the SkyCiv Section Builder tool is not generating the correct second moment of Inertia for my composite DougFir wood and steel "T" top/bottom cord - beams. Forcing me to check the results using hand calculations of strength characteristics of my funny but useful composite shapes. Your lectures on statics and composite beams ..etc, have helped me understand what I need to do. Your presentations proceed in very logical steps, helped by real world examples to help students like me form a better mental picture. Thanks again. SkyCiv is a very good program, fantastic when my designs use standard shapes in the model, but I think my wood/steel beam sections aren't easily "transformed" into a single material for the FEA calculation engine.

[@TheBomPE]

Sounds like some fun stuff you're working on! I'm happy I could help! Thanks for watching!

[@mugaberobert2475]

very clear! thanks 🙌

[@robertokra]

Great video! Thank you, very clear

[@TheBomPE]

Thanks for watching!

[@tunglam5113]

Much appreciation to your lectures sir

[@TheBomPE]

I'm glad you are enjoying them! Thanks for watching!

[@rabihelias7848]

Very clear explanation, Keep it up !!!

[@TheBomPE]

I'm glad you liked it! Thanks for watching!

[@rolativistikwilde1711]

That was a great lecture! I really couldn't thank you enough, so glad I found these right before my finals 💚

[@TheBomPE]

I'm glad you found them helpful! Thanks for watching!

[@midnightson787]

thank you for the great video

[@TheBomPE]

Thank you for the affirmation! I'm glad you liked it! Here are some of my other playlists in case you haven't seen them yet and might be interested: ENGR122 (Statics & Engr Econ Intros): kzbin.info/aero/PL1IHA35xY5H52IKu6TVfFW-BDqAt_aZyg ENGR220 (Statics & Mech of Mat): kzbin.info/aero/PL1IHA35xY5H5sjfjibqn_XFFxk3-pFiaX MEMT203 (Dynamics): kzbin.info/aero/PL1IHA35xY5H6G64khh8fcNkjVJDGMqrHo MEEN361 (Adv. Mech of Mat): kzbin.info/aero/PL1IHA35xY5H5AJpRrM2lkF7Qu2WnbQLvS MEEN462 (Machine Design): kzbin.info/aero/PL1IHA35xY5H5KqySx6n09jaJLUukbvJvB (MEEN 361 & 462 are taught from Shigley's Mechanical Engineering Design) Thanks for watching!

[@sobhanfarahani]

excellent

[@yavuzgenel3228]

Good to see you you have maked cool jobs

[@24fashionchick]

Do you guys know any channels that can explain as clearly as he does but with calculations? My teacher doesn't do lectures and leaves us to self-learn with virtual labs, I can't figure out how to do modulus of elasticity and percent elongation with their data

[@lexxcfd]

Like from my side! Awesome lecture.

[@TheBomPE]

Thanks! Glad you liked it!

[@godfreybanda6777]

Great materials

[@TheBomPE]

Thanks, I'm glad you like them! Thanks for watching!

[@ajithkumarps1974]

Sir your content are great. Im a mechanical engineering student, from India, i urge you to please continue to post more mechanical engineering content. Thank you sir

[@TheBomPE]

I tend to produce new content as I develop new material for new classes I teach. I do plan on continuing to do that! Thanks for your encouragement!

[@saravanashanmukham6108]

Your lectures are quiet helpful, in the sense it is easy to apply to real world projects. Grateful to your contribution, thanks and looking forward to more. I have a question here regarding the shape of the curve from Force Vs displacement to Stress vs Strain (@ 44:30). Shouldn't the curve change shape for stress since it is per unit area and in the necking region, this would behave differently than total force?

[@maddizzle1744]

This is a generalized graph for an introductory course. The students haven't even heard of the concept of necking yet, so I would think it is appropriate to reduce complexity this early on.

[@sabreicb9515]

In your Materials Testing & Characterization section, I think there's a clarity issue between F_applied and F_internal. The curve for F_applied does not look like this during tensile testing.

[@TheBomPE]

Would you mind sharing descriptions of what you are calling F_applied and F_internal, and explaining what phenomenon you believe causes them to differ from one another?

[@Pandhelito]

I always said that a teacher needs to have the ability to teach. It is not sufficient to have the knowledge, you need to have the call. Thank you for this great presentation. Do you still teach the online courses and if yes, where we can find them? Off topic: what software is this one used for the presentation?

[@TheBomPE]

I'm glad you enjoyed the video! This summer, I will offer three courses through Louisiana Tech University. These courses use interactive versions of the KZbin videos on my channel. They can be taken entirely remotely if a student needs that. The courses are Dynamics, Advanced Mechanics of Materials (first half of Shigley), and Machine Element Design (second half of Shigley)...

[@TheBomPE]

I just ink using Microsoft Onenote 2007. I keep waiting on Microsoft to make a better version than that, but they haven't yet.

[@Pandhelito]

@@TheBomPE, thank you.

[@mohankumarmj]

Hello Sir, Could you please explain the difference between Yield Stress and Tensile Stress. I have been reading many definitions , But still find to get an idea. Thanks

[@TheBomPE]

I think the video does a pretty good job of explaining yield stress... as for "tensile stress" ... that is a term that in many sources is used roughly synonymously with the value I'm calling ultimate stress in the video.

[@joshuaolatunji9407]

sir, can you recommend the text used for this course. Thank you

[@TheBomPE]

In this course I use Riley Sturges and Morris, Statics and Mechanics of Materials, 2nd ed. There are numerous high quality texts around these topics (e.g. Beer and Johnston; Hibbeler) but I like how integrated the Statics content is with the Mechanics of Materials in the one I use.

[@medtabernoust3869]

hello sir thank u for this lecture i have a Qs at 41:55 when u star to to explain why the curve curve back down i don't get it ; u said the area decreasing that mean the curve should go up and not back down (and we will dealing with a true stress-strain curve).... this is a stress-strain engineering curve that mean we keep divide on the same area that we start with A(o) we do not take the instantaneous area A(t) the curve should always increase since the tension force in a tensile test is always increasing and the cross sectional area of the specimen decreases, which means that the stress is always increasing...that for a true stress strain curve HOPE U CAN ANSWER ME I'M REALLY CONFUSED

[@boldizsarscheer9977]

the y axis is force! So as the material gets thinner, less force will be needed to move it, so the line will move to the right still because it hasn't break yet but the force to make it stretched will be lower and lower!

[@mas13662002]

I wish you were my instructor Would you please tell me where you are teaching that if there is a possibility I can take a class with you

[@TheBomPE]

I'm flattered! I teach at Louisiana Tech University. I teach online classes in the summer. Dynamics, Advanced Mech. of Materials and Machine Element Design. Maybe I'll see you in one of my courses!

[@mas13662002]

@@TheBomPE For Sure I will take your classes. I have a B.S in Aerospace and M.S in Mechanical And another M.S in Engineering I wish one of my teachers would teach their classes more clearly like you

[@tabenawy]

👍