Mechanics of Materials: Lesson 6 - Factor of Safety Explained, Example Problem

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Пікірлер: 60

  • @ciamaechamae7678
    @ciamaechamae7678 Жыл бұрын

    corrections: pin C components: Cx & Cy resultant at C = 7.45 kips diameter for pin C: 8=7.45/2[pi(d^2)/4] = 0.77 inches = approx 1 inch

  • @orhanp1071
    @orhanp10714 жыл бұрын

    Hi sir! I am 52 years old mech eng following up your lessons with great pleasure. I would like to kindly remind you that the diameter of pin C should be 0.77 in while pin B has 0.78 in (almost the same) diameter. I presume you underline the importance of double shear pin design in this problem. Thanks and best regards..

  • @emilalopez5353

    @emilalopez5353

    4 жыл бұрын

    I am glad that you caught that the diameter of pin C should be 0.77 because I am a student following his examples and was going crazy thinking I’d done my math wrong.

  • @orhanp1071

    @orhanp1071

    4 жыл бұрын

    Prof. Hanson is the king of the instructors. You might keep on following his lessons..

  • @stevemaldonadomelendez1790

    @stevemaldonadomelendez1790

    3 жыл бұрын

    Thanks for the catch! I was running my numbers over and over again until I saw this comment. Regardless this guy is a lifesaver though.

  • @A.Hisham86

    @A.Hisham86

    Жыл бұрын

    Exactly my point! I checked out 3 times the calculation, and I found each time, .77 in at B, and .78in at C.

  • @mikes_channel

    @mikes_channel

    8 ай бұрын

    @@emilalopez5353 3 years later and this comment is still blessing me lmao. Just saved me as well

  • @fernandozanella1395
    @fernandozanella13953 жыл бұрын

    You're such an amazing teacher!

  • @shermaineshootsyou
    @shermaineshootsyou3 жыл бұрын

    can i have you as a prof in my uni ;;; i could just watch his videos and ditch my hour long lectures, thank you!

  • @kramhoogness
    @kramhoogness3 жыл бұрын

    Should your math on pin C be 7.45 divided by (8*2*0.785) before you take the square root? Did you do the division backwards? I got the diameter at pin C to be .77 inches. Rounded up to 1 inch. Both pins are the same are they not? Thanks!

  • @johnk7178

    @johnk7178

    3 жыл бұрын

    You are correct. If you listen to him as he is doing the calculations he multiplies the denominator together, than divides it by the numerator (7.45kips). I believe he meant to key his calculator as 7.45kips divided by ANS on his calculator.

  • @mohammadhamza3937

    @mohammadhamza3937

    3 жыл бұрын

    @@Jordan-vf4up That should be the correct answer

  • @Ssm19494

    @Ssm19494

    2 жыл бұрын

    @@mohammadhamza3937 i got 0.77, he got .78, doesnt really matter when you have to round up to 1 inch for the parameters of the question

  • @christopherraris8667
    @christopherraris86673 жыл бұрын

    Fantastic! I'm enjoying it. Thank you much explaining!

  • @ShAlAmAnAyA3
    @ShAlAmAnAyA33 жыл бұрын

    Now I look at things differently. I am that idiot who always overloads things and thinks it's ok. Now I understand why. So informative!

  • @andyge868
    @andyge8683 жыл бұрын

    Pin C should be .77 too otherwise it doesn't make sense, a double shear pin with the same SF should be smaller compare to a single shear.

  • @Ssm19494

    @Ssm19494

    2 жыл бұрын

    you have to choose between different diameter pins, .25 inch, .5 inch, .75 inch, 1 inch. as an engineer which one do you choose? OBVIOUSLY the 1 inch

  • @haydennagy1601

    @haydennagy1601

    Жыл бұрын

    @@Ssm19494 you would choose 1", not 1.5" as he instructed, he divided 12.56/7.45 instead of the other way around.

  • @estrogenfest
    @estrogenfest3 жыл бұрын

    Love your simplification of why a factor of safety is needed - for idiots that overload stuff

  • @sagefairyy
    @sagefairyy3 жыл бұрын

    your youtube channel is a life saver !!!

  • @haroonwazir6490
    @haroonwazir64903 жыл бұрын

    I really love your videos. But there's a slight problem. I would prefer you put your ads either at the start or at the end of the video. Since they really ruin the much needed concentration and focus. I would voluntarily watch the ads to give your videos the support they need. Regards

  • @manuboker1
    @manuboker12 жыл бұрын

    Wonderful Lectures ! Thanks.

  • @markcorpuz1017
    @markcorpuz10173 жыл бұрын

    Thank you Prof. Hanson. Your KZread channel help me a lot. Pray for me for my upcoming Fe exam! Civil Engineer.

  • @kushalankola1978

    @kushalankola1978

    Жыл бұрын

    Here reviewing for my FE as well! How did you do?

  • @keshaunsumler9376
    @keshaunsumler93763 жыл бұрын

    Why do we not use the y component to solve for shear in the pin?

  • @nikitaperumal5883
    @nikitaperumal5883 Жыл бұрын

    i should just skip my lectures and watch yours. These videos are so good

  • @ethang6569
    @ethang65692 жыл бұрын

    Why arent the x and y reaction forces at c oriented parallel and perpendicular to the pin connection respectively?

  • @mahmoudelbayoumi8800
    @mahmoudelbayoumi88003 жыл бұрын

    Does the ultimate stress equal the allowable ??

  • @marwanrababah4704
    @marwanrababah47043 жыл бұрын

    how comes the actual stress is less than the allowable one?

  • @brentsrx7
    @brentsrx72 жыл бұрын

    Jeff, you are amazing.

  • @susielopez393
    @susielopez3933 жыл бұрын

    Shouldn’t the factor is safety be FS= sigma(actual)/ sigma(allow) ?

  • @brandonpiereder287

    @brandonpiereder287

    2 жыл бұрын

    Yeah I'm wondering this also. If tau_allowable = 12 kips, with a S.F. of 1.5, tau_actual (as in the actual stress the pin can handle before yielding) should be 18 kips and that's what we design the diameter of the of the pin for... Yes? No?

  • @MuhammadAhmad-xz7tu
    @MuhammadAhmad-xz7tu3 жыл бұрын

    Hello Professor, thank you for making it easy on us. Last step when finding diameter of pin C is 0.77” as I double checked. I think your calculator calculated wrong!!!! Please clarify. Thanks 😊

  • @Ssm19494

    @Ssm19494

    2 жыл бұрын

    you have to choose between different diameter pins, .25 inch, .5 inch, .75 inch, 1 inch. as an engineer which one do you choose? OBVIOUSLY the 1 inch

  • @basedvillager
    @basedvillager2 жыл бұрын

    The reason the pin diameter error occurred is because he accidentally thought the d^2 term was in the numerator instead of the denominator.

  • @katenyasudais9944
    @katenyasudais99446 ай бұрын

    There are so many ways professors are defining the factor of stress Am soon concluding that the stress given, ( the ultimate or design or alllowable ) watever u call it is always the numerator

  • @The_Red_Sky
    @The_Red_Sky3 жыл бұрын

    Sir!last diameter of pin C would be .770 instead of 1.298. you placed 7.45 in denumerator instead of placing it in numerator

  • @sphanie

    @sphanie

    3 жыл бұрын

    yea that's what i got too

  • @aliciapark523

    @aliciapark523

    Ай бұрын

    Same

  • @hegelquiroz5839
    @hegelquiroz583910 ай бұрын

    Pin C is 0.77" to nearest 0.25" then, is 1" his answer is correct if you inverse it so it would be (1.298^(-1)) where is = to 0.77"

  • @naffalsultan5088
    @naffalsultan50884 жыл бұрын

    I love you thank you

  • @samernoierat5312
    @samernoierat53123 жыл бұрын

    you are great

  • @wt_4
    @wt_46 ай бұрын

    Thank you 🌹🌺

  • @prathameshjoshi3486
    @prathameshjoshi34863 жыл бұрын

    If we are designing for complete system why don't we consider area of pin at point A

  • @panashemahadzva4278

    @panashemahadzva4278

    3 жыл бұрын

    Its not asked in the qsn being worked

  • @amyzhao6427
    @amyzhao6427 Жыл бұрын

    Hi Professor, I have a question. Since we are calculating the minimum diameter, aka minimum area A, as to the equation T=F/A, shouldn't we use the Maximum T(T allowable) which is 12ksi, instead of T actual?

  • @jaywhaley4688

    @jaywhaley4688

    Жыл бұрын

    This question is asking for the minimum diameter of the pins ~to allow for~ a factor of safety of 1.5. Another way of approaching this problem is to think about T(allowable)/12 kN as the defined value in which the system will fail, and T(actual) as the value we are changing in order to receive a F.O.S of 1.5. Diameter is simply the variable within T(actual) that determines the value of T(actual) itself. When we increase the diameter, the shear stress decreases (diameter is in the denominator) resulting in a lower T(actual) value and a higher F.O.S. Therefore, when we increase the diameter, F.O.S increases as well. This is why the question asks for the ~minimum~ diameter

  • @amyzhao6427

    @amyzhao6427

    Жыл бұрын

    @@jaywhaley4688 Ahhh! We're using T(actual)8 instead of 12 just to be conservative aka satisfy the safety factor:D Thank you for the help

  • @UzsDc1UZ
    @UzsDc1UZ Жыл бұрын

    The dodge example was soo funny 😂😂

  • @kevinrath4223
    @kevinrath42234 жыл бұрын

    If Fab is positive should the force be going to the right?

  • @adriftfoolish1

    @adriftfoolish1

    4 жыл бұрын

    When looking at the sum of Moments about A, Fab is causing a counter-clockwise rotation. It is positive in that regard. If you are taking the sum of all X forces, then Fab is negative.

  • @jobewankenobi5430

    @jobewankenobi5430

    3 жыл бұрын

    Think of positive and negative numbers as verification for your “guess direction.” If the number is positive then you guessed correctly!

  • @khalidalabood7092
    @khalidalabood70924 жыл бұрын

    👍👍👍

  • @kyeler
    @kyeler Жыл бұрын

    1newton/1millimeter is equivalent to 1n/1m^3 in other words, 10^3 so, a newton divided by a millimeter is not a megapascal, but a kilopascal. Do the math for 13kn/7853.98m^-3 and you will see that it equals 1655 pascal or 1.65 kPa

  • @Universityoftech
    @Universityoftech3 жыл бұрын

    the angle that i got is 63.43 from arctan 4/3 is that wrong? how did you get 60?

  • @estrogenfest

    @estrogenfest

    3 жыл бұрын

    it looked like he made it up. how did you get arctan 4/3?

  • @shayanahmad9945
    @shayanahmad99453 жыл бұрын

    It would be grateful if you shorten the ads...Thank you

  • @juniorjay001
    @juniorjay0013 жыл бұрын

    All the letters being confused is confusing to follow