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  1. 40818

    springs near plasticity

    Mike great, (hopefully!) I'm looking at a design which is keeping a torsional spring under load near yield (95%) for a sustained period of time. the spring is of a very high strength material (2000MPa UTS 0.9Y). i'm slightly concerned regarding creep relaxation and also stress corrosion...
  2. 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?
  3. 40818

    Pocketed Panel Shear Buckling

    edbgtr: The analysis your looking for has been used by Airbus and its previous incarnations in SOR51 in its original form. The pad up at the panel edges effectivley reduce the panel size if i remember it at its most basic. The theory and application goes way back in time long before machined...
  4. 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)?
  5. 40818

    continuous plate analysis - Timoshenko

    Thats the problem really, there isn't a worked example as such, just a load of theory equations, which don't look like a walk in the park, especially when your looking at a continuous structure. Didn't really want to do a FE for the very reason that I have never done one by hand.
  6. 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.
  7. 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.
  8. 40818

    linear and nonlinear gaps

    Have you carried out a hand analysis of the structure?
  9. 40818

    Really high stresses in thermal analysis

    If your running nastran, there is a lagrangian option for rigid elements, which i believe you will need to switch on.
  10. 40818

    Modeling Simply Supported Members

    Not sure of the system your using, but have you any pin-flag options?
  11. 40818

    Modeling Simply Supported Members

    Got a picture to help visualise?
  12. 40818

    Correlation between experimentaion and patran

    More info may help. You have a constant bending moment so whats the handcalc strain?? and how does it compare to the real & FEM? Have you modelled the sandwich correctly and ensured that your comparing apples with apples, i.e. that the strain your looking at the FEM really is the same distance...
  13. 40818

    Plastic redistribution around a hole in a panel

    The original methods used by Hawker Siddley (now in various guises at Airbus) use SOR25 to approximate the stress distribution around the edge of the hole cutout. Notably developed post comet disaster.. SOR51 is used to analyse the flat or curved panels (no hole) for a variety of loadings and...
  14. 40818

    Plastic redistribution around a hole in a panel

    Your problem is a common occurance on Airbus wings. You need to be careful as the extent of plasticity can be quite large and beyond the scope of using Neuber. There are a variety of methods and tools (not FE) which have been developed to accuractly estimate the local effect (at the hole) and...
  15. 40818

    radial displacment in Patran with tet elements

    Use a cylindrical coordinate system aligned along the tube, and use that system to enforce displacement
  16. 40818

    Protected Mathcad sheets

    If you dont know the password, try opening the file in a text editor and look for the password, its normally pretty easy to find.
  17. 40818

    CBUSH or RBE2 for BOLT ?

    Depends what you want out of the model really, RBE2 will suffice for some instances other ones would require bushes. if you use bushes then you can control teh stiffness of each bolt to represent the correct stiffness based on bolt type, plate material etc, the rigid element wont allow this...
  18. 40818

    Equipment rack stress analysis

    I have experience in tubular equipment racking on C-130s. First ensure it works statically @16g and the other critical cases, by hand preferably and dont immediatley worry about the dynamic effects. The second part your looking at seems to be impact analysis really. Ballpark figures would be to...
  19. 40818

    Fastener failure mode

    If your working outside the bounds of the SRM, then you will need to get a "no technical objection" or such like from the OEM. Just because the fastener type is "shear or tenison type" may not have any bearing (exscuse the pun) on the loads applied to it or its failure mode. Would you please...
  20. 40818

    Explanation for Shape Function (linear)

    Very good......but why?

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