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  1. timtimtim44

    Composite Structure Optimisation Methedology

    Hello. I don't have a lot of experience working with numerical optimization point of view. But, I have participated in establishing many other lay-ups using a more basic approach. And based on that, I would say that the optimum lay-up would probably require fewer different fiber directions than...
  2. timtimtim44

    Laminate Stiffness, Test vs Predicted

    We are testing according to ASTM D3039M, mostly high modulus fibers cured at 180°C with 55% Vf for fabric and 58% for woven. But similar results is also observed when testing T700 UD laminate with higher resin contents (roughly 48%). We normally measure strain with extensometers, but we have...
  3. timtimtim44

    Laminate Stiffness, Test vs Predicted

    Hello all. When comparing the stiffness results from a tensile test of a lay-up (0/90/+/-45 in differenct combinations) with the stiffness predicted using classic laminate theory (CLT), I have noticed that it's not uncommon for CLT to overpredict the stiffness. The measured stiffness is usually...
  4. timtimtim44

    Dry prepreg after VBO cure

    Thank you Compositepro for your input. If I may, I'd like to ask some further questions on this topic. We cut our product into pieces the other day the to see what it was like on the inside, and the results were both positive and negative. On the positive side, our final CPT came very close to...
  5. timtimtim44

    Dry prepreg after VBO cure

    Hello. We recently manufactured a larger CFRP sandwich article using OOA VBO technique and we were a bit surprised that the resulting prepreg appeared to contain much less resin than usual, and by this I mean that the fibers are visible in many places. This was especially appearant in the...
  6. timtimtim44

    Using expired prepreg

    Hello. I'm wondering if anyone has experience with using expired prepreg (i.e. expired freezer-life and not out-life). The material in question is an epoxy/glassfiber woven prepreg which will be used locally as a corrosion barrier on a larger epoxy/carbon fiber structure. I'm thinking that we...
  7. timtimtim44

    Using solid laminate elements

    I managed to get a hold of an NX solver, so hopefully as soon I get the installation sorted I should be able to run my simulation. I noticed that when I export my model as an NX .dat-file it uses PCOMPS elements. Does anybody now if there is a way to get the ply's to orient themselves according...
  8. timtimtim44

    Using solid laminate elements

    Righto, that was a good explanation on the elements. Is there a problem that currently I only have access to two types of solvers? I can solve it using either MSC Nastran and/or Abaqus... will any of them work?
  9. timtimtim44

    Using solid laminate elements

    Well I haven't been able to get as far as an error message from Nastran yet, but I will post it if I get one. I'll keep working on the mesh. I'm not sure that I follow you on the element dimensions, are you saying that nastran writes one entire lay-up to each element, i.e. should I mesh it so...
  10. timtimtim44

    Using solid laminate elements

    Ok, I worked my way around the CPENTA elements but the result is still the same. I have uploaded my model as a femap neutral file, if you have time to look at it I would greatly appreciate it. I hope it's rather self-explanatory... I've only modeled a segment, I intend to put circular symmetry...
  11. timtimtim44

    Using solid laminate elements

    Thank you, I'll post it when I return to work tomorrow morning. Been thinking about my model as I walked home, there's no unused lay-ups or properties as far as I know but I'll double-check that. However there is two holes in it. One of which I use for constraining it (pinned constraint...
  12. timtimtim44

    Using solid laminate elements

    Cheers for that, but I have encountered additional trouble now. When I ignore it things seem to be working until I try to export the analysis file. Then I get the error message that "Laminate Solid Property 4 is not supported". In the .dat file created there is no property card created which...
  13. timtimtim44

    Using solid laminate elements

    I've tried both 3D orthotropic and anisotropic material. FEMAP says that both are invalid material types when I try to incorporate them in the lay-up editor...
  14. timtimtim44

    Using solid laminate elements

    Hello! I'm trying to model a composite using the built-in solid laminate element type which requires me to specify a lay-up. However, it seems that none of my materials seems to be appropriate. I constantly get the message "invalid material type" when I try to select them in my lay-up editor...

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