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Recent content by Trajano

  1. Trajano

    effect of local stress concentrations on the strength

    RPstress, thank you for the document you left. It answers my question. Thank you to everybody else for your contributions.
  2. Trajano

    effect of local stress concentrations on the strength

    Thank you for all your answers. I am prone to think that things would happen as rb1957 describes. "A (notched) will fail at a slightly smaller load than B". Dougt115 and tbuelna: I do not think it is as simple as you describe it. If we just applied the Kt factor from Peterson to the nominal...
  3. Trajano

    effect of local stress concentrations on the strength

    Good morning/evening, Sirs I am thinking of the effect of local stress concentrations on the strength of the metal parts. In order to clarify my ideas, I have thought of a simple test: Let's imagine we have a test specimen A (made of aluminium, or steel) with a rectangular section of width "a"...
  4. Trajano

    Cadmium plating on a flap track... what purpose will it serve?

    @ RPstress: you say you are curious to know from anyone working on flap tracks in the last few years whether low alloy steel is still being used. In one of the last Airbus aircrafts, the flap tracks are machined from titanium.
  5. Trajano

    Tension fitting analysis with filler

    Firts of all, I thank you all for answering. Please, let me sumarise what I have understood about the methods exposed here (see attached file). Please, correct me if I am wrong. - edbgtr suggests a cantilever model with concentrated loads (model A in the attached sketch) - rb1957 proposes a...
  6. Trajano

    Tension fitting analysis with filler

    Hi rb1957, thanky ou for your answer. Actually what you say was my first impression too. But then I found in Flabel (Chapter 5, page 321 and 322): "For higher loads applications, a tension clip can be safely beefed up by using a radius block..." (it doesn't say how the filler is helping though)...
  7. Trajano

    Tension fitting analysis with filler

    Hello, I am updating an old calculation with new loads. It is a channel type tension fitting analysis based on Lockheed 88a. In the old calculation, in order to improve the RF, a filler was added. The way the RF was calculated was using an *equivalent end pad thickness*: t_eq = SQRT (t_pad^2 +...
  8. Trajano

    Shell elements- Normal Rotation

    Hello, I have never used shell elements in Marc before. I would appreciete it very much if you could answer these two questions: 1. Have the shell elements stiffness in the rotation normal to the shell plane? 2. If not, how can this problem be fixed? Thanks in advance.
  9. Trajano

    Nonlinear analysis. Reserve Factor definition

    Hello, Lets say that I have a F.E. model of my structure. the structure is made of a material whose ultimate tension allowable stress is Ftu. I perform an analysis for an ultimate load case and I read the maximum stress Smax. - If the analysis is LINEAR I would define the reserve factor like...
  10. Trajano

    Post-bearing and Ultimate Bearing Bllowable concept

    Hello, * Problem: lets say that we have 2 Al plates (0.2 inches thick) joined by means of several Ti fasteners. At Ultimate Load, the load of one of the fasteners is higher than the Fbru (ultimate bearing allowable). * Questions: 1. Is it possible to consider that this fastener can take load...
  11. Trajano

    Nastran sol 106 & BUCKLING

    Thomas, your explanation is very clear and useful, thank you. Kellnerp, thanks again for your posts. I misundestood your question about "how close the solutions are". In fact the first eigenvalues are quite close (0.987; 1.033; 1.042; 1.083). My model is a section of a Aluminium longeron. It...
  12. Trajano

    Nastran sol 106 & BUCKLING

    kellnerp, the shape of the buckled structure resulting from the linear buckling eigenvalue solution is the same as the one from the nonlinear static solution (of course in the nonlinear one appart from the bucking there are other deformations in other zones that have nothing to do with he...
  13. Trajano

    Nastran sol 106 & BUCKLING

    Thank you both for the replies. drk186, sol 106 is the nonlinear or linear static. And, please correct me if I´m worng, but I think that if I don´t use the PARAM,BUCKLING, the SOL 106 doesn´t calculate any eigenvalue. Hence, my problem is how can I tell if certain part of the structure has...
  14. Trajano

    Nastran sol 106 & BUCKLING

    Hello I have a FE model with non linear material properties. If I run a SOL 106, will I be able to see the buckling modes? Tips: 1. There is also a method (that implies the use of PARAM,BUCKLING among other things) to calculate the buckling modes. But I´m not talking about that, just about a...
  15. Trajano

    Web Bend Buckling

    Hi edbgtr, if I didn't misunderstood you, you want to study stability of the web of a bending beam. If so, I would suggest to consider the next: - if the Web is not high and thin: beam bending theory: no buckling. - if the Web is high and thin: diagonal tension When a beam is submmited to...

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