Fracture Toughness Example: Allowable Pressure in Cracked Titanium Tube; Optimizing Yield Strength

LECTURE 15b
Playlist for MEEN361 (Advanced Mechanics of Materials):
• MEEN 361: Advanced Mec...
Playlist for MEEN462 (Machine Element Design):
• MEEN 462: Machine Elem...
This lecture was recorded on January 22, 2020. All retainable rights are claimed by Michael Swanbom.
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[@aleksandrshevchenko8867]

Thanks for the lecture! Very much appreciate you are sharing them. I would like to add that when at around min 27 you were discussing the chart of Fracture Toughness of Titanium Alloys, those 2 curves come from 2 orthogonal orientations typical in extruded materials: O, T, L, and RD stand for Orientation, Transverse, Longitudinal, Rolling Direction respectively. In sheet metal, how it's being rolled plays a role and make slightly different grain package and material get different strengths in a different orientation, and hence orientation / rolling direction matter from a strength perspective, but in the actual parts, you don't always know rolling direction so it is probably possible to interpolate if you have extra data and as you said how the material being processed, although in the case of tubes the direction is more or less straightforward.

[@anuragchakraborty8766]

This is brilliant. Thank you so much for sharing this.

[@TheBomPE]

Thank you for your kindness! I'm glad you liked it!

[@kev7355]

Based on the equation for stress of the tube, you will see higher hoop stress at the internal radius. ie: r = 10mm. And the way you treat it like uniaxial stress yields almost the same result as with Tresca Criterion if the pressure is very small compared to the stresses involved.

[@karthikesan8756]

great explanation. thank you

[@TheBomPE]

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

[@Potentflowconsult]

Thanks always!!!

[@TheBomPE]

I'm glad you liked it! I hope you are doing well!

[@markbaidoo8270]

Good lecture. Do you have any videos that highlight more on how to solve analytical solutions and produce analytical graphs in hydraulic fracturing or fracture mechanics in general.

[@theAV8R]

At 14:40, you say we should use ro as our point in the wall to calc allowable tangential (hoop) stress. Why not ri, which would (conservatively?) lower our permissible internal pressure to ~33 MPa in lieu of the calculated ~37 MPa? (This has me wanting to figure out why the crack wouldn;t start on the inside instead of the outside, I'll go ahead and figure out what I'm missing) I can't thank you enough for putting these up online!!

[@ahmeduosri1623]

Thank you for your great work, could you suggest a good book in fracture mechanics, specially concrete fracture mechanics

[@TheBomPE]

The book I have referred to in a few of my professional dealings is by Hertzberg. I haven't done any work specifically with concrete fracture. I also haven't done a heavy review of other available books. I'm sorry I'm not more help, but thanks for watching!

[@KIMIRAIKKONE198N4]

can we proof or is there a way to demonstrate that the stress at the bottom tip of the crack will be bigger than the stress at the inner radius Ri ???

[@michaeltamajong4659]

Prof. please can you reference the textbooks used for this course and the ENGR 220 course.

[@TheBomPE]

In this course I use Shigley's Mechanical Engineering Design, and in 220 I use Riley Sturges and Morris, Statics and Mechanics of Materials. Thanks for watching!

[@milindmathapati]

hello, thanks for uploading such great lessons. if maximum tangential stress is at inside of the tube how r is taken as 11.24mm isn't it should be 10mm

[@KIMIRAIKKONE198N4]

r is where you want to measure the stress... so its a variable..... Now, but r(o) is the outer radius of thr cylinder by removing from it the crack length (12 - 0.76 = 11.24)

[@jimflatt8512]

When calculating part a), why was r=ro=11.24mm? Isn't r the average radius of 10.62mm?

[@vidameidanshahi5857]

Thanks for the great work! What's the text book?

[@TheBomPE]

I'm glad you liked it! I was teaching from Shigley's Mechanical Engineering Design, 10th ed. 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!