Mechanics of Materials - Angle of Torsion

AI Thread Summary
The discussion focuses on solving a torsion problem related to the angle of twist in a mechanics of materials context. The user initially struggles with calculating the twist angle at point B, despite correctly identifying maximum stress in section CD. Clarifications reveal that the user mistakenly used the wrong moment of inertia value (Io) and needed to sum the twist angles of each section correctly. The importance of using radians and proper sign conventions in calculations is emphasized. Ultimately, the user successfully arrives at the correct result after revisiting the problem with the provided guidance.
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Max stress occurs in section CD where the moment is 400 N-m, not in AC where the moment is 200 N-m.

You also have the wrong value for Io.

Twist angle at B is the sum of the twist angles of each section.
 
Max stress occurs in section CD where the moment is 400 N-m, not in AC where the moment is 200 N-m.

Fair enough, I miswrote-- but I got the right answer yes?

You also have the wrong value for Io.

Where? I used the right formula according to wiki, to my understanding my answer is wrong because of this ->
Twist angle at B is the sum of the twist angles of each section.
EDIT: Retried it with what I think is your idea...
http://img204.imageshack.us/img204/7044/applying.jpg

Adding the results together does not equate to 1.18 deg
 
Last edited by a moderator:
Femme_physics said:
Fair enough, I miswrote-- but I got the right answer yes?
Indeed . Sorry.
Where? I used the right formula according to wiki, to my understanding my answer is wrong because of this ->
My apologies again, you are correct...I was thinking Ix instead of Io.
EDIT: Retried it with what I think is your idea...
http://img204.imageshack.us/img204/7044/applying.jpg

Adding the results together does not equate to 1.18 deg
No, but your method is correct. Remember that the result will be in radians. And don't forget the proper use of your plus and minus signs when doing the addition.
 
Last edited by a moderator:
Moderator's note: thread moved to "Engineering, Comp Sci, & Technology"
 
Indeed . Sorry.
My apologies again, you are correct...I was thinking Ix instead of Io.

:)

No, but your method is correct. Remember that the result will be in radians. And don't forget the proper use of your plus and minus signs when doing the addition.

Ah...now I see.

Alright, then. I'll give it a crack when I get home today. Thanks!
 
Last edited by a moderator:

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