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  1. 40818

    springs near plasticity

    Hi, Does anybody have any experience of springs (torsional) under constant loading which is very close to the material yield stress?
  2. 40818

    Specific Composite Design Factors

    With reference to the use of composites within the aerospace industry, has anybody any experience of the use (and rationale for) additional design safety factors above and beyond proof (1.25) and ultimate (1.5)?
  3. 40818

    continuous plate analysis - Timoshenko

    Hi, has anyone ever carried out a continuous plate analysis (as described in timoshenko plate and shells)? If so, any tips on it.
  4. 40818

    Tangent Modulus and secant formula?

    Is it feasable to use the tangent modulus of elasticity rather than simple E in the secant formula for eccentric loaded struts? I believe that the secant formula is only valid up to the prop limit hence it should only be used by limiting the edge fibre stresses at most to Fty. Cheers.
  5. 40818

    Plastic bending -using FTU

    Hi all, Does anyone have any knowledge of using plastic bending factors on FTU rather than FT2 (FTY) to calculate an allowable stress? Rectangular section with K=1.5 (or esdu 01.06.01 which comes to 1.4). I always thought it was the yield moment multiplied by the shapefactor (i.e 1.5).
  6. 40818

    panel post buckled capacity

    Hi all, I'm looking for some sort of confirmation regarding whether a panel web can support shear loads after it has buckled under a uniaxial compressive load.. Cheers in advance.
  7. 40818

    ESDU 80035

    Hi, I'm looking for help using ESDU 80035 (Buckling of outstanding flanges , direct stresses varying linearly or parabolically). This EDSU allows you to determine a new buckling coefficient depending upon the stress state of the flange (i.e under varying degrees of bending stress). My problem...
  8. 40818

    torsional natural frequency - beams

    Hi, with simple structures such as beams (fixed,simply supported, cantilevers etc) its pretty well documented how to calculate the natural frequencies of the beams for different end restraints. Now, from FE analysis on many real structures, i am also getting an abundance of torsional modes, and...
  9. 40818

    adhesive shear allowable under torque

    I'm having trouble thinking about how to come up with a ballpark allowable value for a bonded attachment under a torque load. The attachment pad is circular and is bonded to a baseplate. The pad has a direct shear allowable of say 100lb. However, it is subjected to a force which will induce a...
  10. 40818

    Results comparison

    Thought i'd throw a question out there: If you have a coarse grid model of say 9 Quad4 elements in a 3 rows of 3 columns (Nastran) and apply a load to the model to generate shears and endloads within the quads. And then use hand calcs to size the panels, all well and good. If a finer grid model...
  11. 40818

    simple question

    Hi, i have a simple question that i'm mulling over. If you imagine a simple flat rectangular beam built from quad elements, with 2 supports and an overhang. A "downwards" load is applied at the overhang edge, kinda like the badly drawn drawing below. The supports are just single nodes in line...
  12. 40818

    quad - size and thickness

    I was always taught that its good modelling practice when using shell type elements to have a reasonable relation between the element side lengths to the proposed material property thickness. For example if the material being modelled was 1mm thick then a typical minimum element size would be...
  13. 40818

    Fastener Flexibility In Composite Joints

    I have stumbled across a part of Cranfields Research library, where you can download Phd, Masters thesis etc. One that caught my eye was by Blong Siong, which is "Fastener flexibility in composite joints for aerospace structures". It follows on from Lee Franks thesis that has links abounding on...
  14. 40818

    BS s527 steel

    Does anybody have Sn data for BS s527 stainless steel 18Cr/10Ni (Nb Stabilised) softened sheet? Also, is there an equivalent sheet spec around (i.e AISI, ASTM, EN etc). Thanks.
  15. 40818

    Modal Effective Mass Fraction

    Thought i'd post in this forum rather than in the FE one. Does anyone have any decent references which help with the determination of a local or global normal mode. Apart from looking visually at the deformed shape, strain energy and the percentage modal effective mass fraction. Oh, and...
  16. 40818

    Nastran/Patran Contact Analysis

    Hi, I have a honeycomb sandwich barrier (aluminum skins and core) which is held in say 4 positions. I wish to apply a pressure load to the structure and get some decent results out. Now on the opposite face to the loaded side their is a flat structure which my barrier is allowed to contact, and...
  17. 40818

    Average age?????

    Rather a strange one, but a few weeks ago i started a thread about basic engineering loss. But it has just came to me the thought that any trend might be governed by how old we are. Maybe we are more likely to want newbies to learn the "proper" techniques that we were taught rather than just FEM...
  18. 40818

    EBT Allowable deflection in beam

    Right, once and for all i seek consenus on a grey area which will no doubt provide debate. For a simple engineering theory of bending, what would you take as an allowable deflection for a give thickness, radius of curvature, etc. I have read of values from 0.5t through to 2t in various books...
  19. 40818

    Crash loads

    Hi, I'm working on a concept scheme in which a structure in a cargo bay has to react a big 9g fwd crash load, all well and good, but in a particular area it will impart a reaction load onto the aft vertical pax door surround. I have tried my best to show it below. !....!...........!....! ...
  20. 40818

    Engineering knowledge loss??

    Hi all, just a quick ponder... What is the general consensus regarding the loss of classical engineering knowledge due to the ever increasing reliance on "black box technology". I believe that these very useful tools are exactly that, tools, which should be used by a stressman or designer to aid...

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