1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Deflection of cantilever

  1. Aug 13, 2016 #1
    1. The problem statement, all variables and given/known data
    in the notes , i dont understand the circled part . I dont understand why the circled part moment M is in anticlockwise direction ... Shouldnt it be in clockwise direction ?

    2. Relevant equations


    3. The attempt at a solution
    As we can see , the P at the one end will cause the cantilever to bend in clockwise direction . So , i think that the direction of moment M is wrong ...
    It should point in clockwise dircetion , which means M = -P(∂ -y) , am i right ?
     

    Attached Files:

    • 356.jpg
      356.jpg
      File size:
      36.9 KB
      Views:
      36
  2. jcsd
  3. Aug 13, 2016 #2

    PhanthomJay

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    The sketch shows the internal force and moment at the cut section, required for equilibrium. Applied moment is clockwise, so internal moment is ccw. Applied force P is downward, so internal force P is upward.
     
  4. Aug 14, 2016 #3
    ok, can you look at the example below, why the circled moment M is same direction with the moment due to applied force P?
    since they are in the same direction,how can they are in equilibrium?
     

    Attached Files:

    • 359.jpg
      359.jpg
      File size:
      31.5 KB
      Views:
      29
    • 360.jpg
      360.jpg
      File size:
      16.6 KB
      Views:
      28
  5. Aug 14, 2016 #4
    so, in the deflection equation, we are focusing on the internal moment? why?
     
  6. Aug 14, 2016 #5

    PhanthomJay

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    The author assumed a clockwise internal moment but the calcs show in the 2nd images that it is actually negative or ccw. You again are looking at complex examples in trying to understand basic equilibrium concepts.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Deflection of cantilever
Loading...