Difference between Euler's critical load and Buckling Analysis "F" parameter

LFSS
LFSS Altair Community Member
edited October 2020 in Community Q&A

Hello, all

I've got a trussed structure I'm woring on, but when I call a buckling analysis, it gives me this result:
image 
But, when I extract the element forces via ELFORCE, it gives that, in that particular member, Ive got a 167N force, which I used to calculate manually Euler's critical load. Pcrit equals 42N, but the F paramenter in OptiStruct (which should give the ratio of Euler's load with the acting load) gives me a far lower ratio. Any clue why that is?

 

thanks in advance! 

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Answers

  • Adriano Koga_20259
    Adriano Koga_20259 New Altair Community Member
    edited October 2020

    Hi,

     

    are you sure the boundaries of your bar are exactly as the euler's assumption?

    the stiffness of the connections might be influencing your response.

  • LFSS
    LFSS Altair Community Member
    edited October 2020
    Adriano Koga_20259 said:

    Hi,

     

    are you sure the boundaries of your bar are exactly as the euler's assumption?

    the stiffness of the connections might be influencing your response.

    well, I'm modeling the bar as a pinned-pinned bar, and applying the corresponding Euler equation. Could the connections not act as a pinned condition?

    If we're assuming a pinned-pinned bar, we have that (for the first mode and with my conditions):

    image where EI = E*I = GPa * m^4 and L is in meters
    But in the model I extract a 167,1N using ELFORCE.

    Could I be wrong in my assumptions and HyperWorks uses another method to calculate it?

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