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  1. jcmbl

    Random time-varying concentrated loads?

    mihailmi, actually I was asking for the bits of your subroutine just to have a model for my problem. I've never used subroutines, so it's a bit confusing at the beginning. From what I understood, the DLOAD subroutine, as well as UTRACLOAD, is called for each integration point. That means I have...
  2. jcmbl

    Random time-varying concentrated loads?

    mihailmi, can you please share your UTRACLOAD subroutine? How do you pass the pressure magnitudes on? I guess you are doing some flutter analysis, but for static aeroelasticity, a DLOAD wouldnt be more appropriate? Cheers
  3. jcmbl

    map pressure onto another surface

    and for cambered airfoil?
  4. jcmbl

    map pressure onto another surface

    Guys, I want to map the pressure distribution from the outer skin onto the camber line. I assume the structural integrity of the airofoil is provided by the camber and no other stiff internal structures. The pressures on both surfaces after mapping are equal if the airfoil is thin (max 6%...
  5. jcmbl

    aeroelasticity study

    pja, I'm still not clear. You are talking about timestep, so I guess your analysis is an explicit and time-dependent. That leads me to the complex part of aeroelasticity, i.e., dynamics (flutter, buffeting etc). I'll better start with static aeroelasticity, where your time step has no...
  6. jcmbl

    aeroelasticity study

    ...sure exactly how to approach my problem: an airfoil with a simple actuated flap. I deflect the flap with a force F, run CFD, extract pressure p=1/2*rho*V^2*Cp, apply this p onto the structure and run FEM model with F+p fron unstrained state or just p from equilibrium state with F? And so on...
  7. jcmbl

    fitting an elastomeric material

    Hi guys, I'm using a hyperelastic foam core in my FE model. I am using Abaqus to fit the material so that I can optimize the parameteres defining the foam core during bending. The parameters are: mu (i.e., shear modulus), alpha (i.e., shape of the stress-strain curve) and beta (i.e., shape of...
  8. jcmbl

    output file with displaced coordinates?

    if you don't want to be bothered with .inp file from a text editor, you can also add the card whithin CAE through Keyword Editor (see meniu) *Node Print [freq=99999 - optional] U If you adjust your deck from a text editor, and then run it with CAE, you won't get the anything in .dat file (at...
  9. jcmbl

    aeroelasticity study

    Hi guys, Does anyone have any experience in doing some aeroelasticity studies? I mean coupling CFD (e.g., Fluent) and FEA and issues such as pressure distribution from CFD into FEA mesh or type of appropriate FEA job. I've read a paper wherein a FEA bump is subject to aeroelastic forces...
  10. jcmbl

    Random time-varying concentrated loads?

    mihailmi, if you got a solution to your problem, please share it, as I've experienced nearly the same difficulties. Thanks, J
  11. jcmbl

    mass and stiffness matrix extraction

    ...matrix of a system (not only for an element)? I need this kind of output to handle further with some other software for some research purposes... I tried using *Substructure matrix Output card, but it seemed not be working...does anyone have experience in using this card or smth similar? J
  12. jcmbl

    official data on performance

    Hi guys, Does anyone know any paper or book with official data about the performance of a wing of any commercial airliner, providing ailerons deflection and roll moments, pitch due to roll, etc. Cheers
  13. jcmbl

    Compute an integral from data points

    sorry guys for the stupid question. I did some drawings to help me understand the area I needed, but it was proved I was doing something silly (I was getting some open segments of the curves which I couldnt compute). Of course the area is the difference between the 2 curves, although I'm not...
  14. jcmbl

    Compute an integral from data points

    Hi guys, I have 2 weird sets of points to define 2 curves. I need to compute the area between these two. Is there any straightforward way to do it? The position of the curves is changing with respect to X axis, so I'd need a general methodology to do my task, not just for a specific set of...
  15. jcmbl

    buckling

    try pasting the code in here to peruse it. Maybe you just use some other axes for load function, if you haven't used CAE. I know there is in the manual an example like yours..try fiddle it, although there's nothing clever in it.
  16. jcmbl

    Wing performance issue

    Hi guys, I need to assess the performance of a wing when increasing the camber of the grid sections, getting at the end a more cambered tip. I do not take into account any high-lift devices (e.g., aileon) but probably the performance I seek is with respect to a conventional wing. Does anyone...
  17. jcmbl

    VGK for wings

    Does anyone have any experience using VGK for wings on Linux machines? At least some other softwares able to run in batch mode on Unix machines, for relatively simple wing geometries. Fluent is too slow. I'd appreciate any help. Suhoi
  18. jcmbl

    NURBS surface

    Hi guys, Is it possible with Matlab to build a surface based on 2 NURBS? I've used a CAD package for that, but the script runs for a while. I need to extract the points on the surface (conducted by 2, 3 or even 4 NURBS as bounds, to form a closed profile) equally spaced on the both main axes...
  19. jcmbl

    Nonlinear analysis in Abaqus

    it is clearly written in the doc that (at least) the small-strain shell elements use Total lagrangian strain in stresses. Finite membrane-strain elements are in corotational formulation.
  20. jcmbl

    Sketched Splines

    dbeat: u r probably talking about the passing points and not the control points. They are different. One way to create parametric NUPBS: construct through constraints the control points in a sketch. This is easy for a simple model. The manipulation is up to you: design table, or by simply doing...

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