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

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[ciamaechamae]

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

[orhanp]

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..

[ShAlAmAnAyA]

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!

[markcorpuz]

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

[nikitaperumal]

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

[andyge]

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.

[kramhoogness]

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!

[haroonwazir]

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[sagefairyy]

your youtube channel is a life saver !!!

[katenyasudais]

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

[MuhammadAhmad-xztu]

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 😊

[basedvillager]

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

[The_Red_Sky]

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

[susielopez]

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

[marwanrababah]

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

[christopherraris]

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

[ethang]

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

[amyzhao]

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?

[mahmoudelbayoumi]

Does the ultimate stress equal the allowable ??

[GolemGamingWWR]

There is something I am confused about. The allowed shear stress should be smaller than the actual, so shouldn't the actual be allowed times factor of safety which is 12*1.5=18 instead of 12/1.5=8? Other wise people follow the allowed 12 exceeding the actual 8 and gets it damaged.