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  1. Mario_Aero92

    Natural frequency of a damped system, oscillated with a sinusoidal displacement

    Exactly! Thank you! Now I have my concepts more clear. I was mistaken with the "1/2" factor, I wanted to say "2". As you say, that frequency (what I called displacement resonant frequency) is the one for the forced vibration, induced by the oscillatory movement of X. Thank you!
  2. Mario_Aero92

    Natural frequency of a damped system, oscillated with a sinusoidal displacement

    Hi! Thank you for your answer! Yes, actually I forgot to say that I assume underdamped system of negligible damping factor for my intuition :). So, it is as you say. The thing is that I know that this value comes from solving the characteristic equation of the homogeneous part of the...
  3. Mario_Aero92

    Symetry 3pt bending

    Hi! If you are fully sure that material and cross section properties of the beam are symmetric with respect to the mid plane of the beam, then you can do the following: Apart from material and structure symmetry, there must be symmetry in the geometry and loading condition. Hope it helps!
  4. Mario_Aero92

    Natural frequency of a damped system, oscillated with a sinusoidal displacement

    Hi! I have the following system: x is am imposed motion and y is the output that I obtain. I would like to calculate the natural frequency of the system. My intuition says that it is equal to sqrt((K+k)/m), but I am not sure how to derive this value from the equation of motion of the...
  5. Mario_Aero92

    Parameters for linear Drucker Prager

    According to Abaqus User's manual, beta would be friction angle and Psi would be the dilation angle. That expression is correct, but as I said I Have the value of beta.
  6. Mario_Aero92

    Parameters for linear Drucker Prager

    Hi, Yes, the dilation angle is basically related to the direction of the plastic flow. It is the direction of the differential plastic strain with respect to the yield surface in the meridional plane. When associated plastic flow is assumed, then the dilation angle is equal to the friction...
  7. Mario_Aero92

    Parameters for linear Drucker Prager

    Hi! Thank you for the answer. I actually found this document in the internet too, but I still cannot understand how to obtain the dilation angle. Anyways, in principle I do not have that value of plastic Poisson ratio so I cannot use it.
  8. Mario_Aero92

    Parameters for linear Drucker Prager

    Hi, I want to model the compression of a polymer cylinder. For that purpose, I want to use a linear Drucker Prager yield criterion with no hardening and a non-associative flow rule.  I have seen that in Abaqus the linear Drucker Prager requires the introduction of three parameters: friction...

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