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  1. orangepeel

    'Flexible' Hardcoat?

    For future reference, there are a number of rigid polyurethanes / polyureas that provide good wear resistance. I have used Huntsman's RP 6444 for a number of applications. They claim that it is used as a coating on ore carriers or something similar.
  2. orangepeel

    Composite FEA

    Spirit, Ansys, MSC.Nastran, NENastran, MARC, and IDEAS also have composite plate elements that one can use. Most FEA packages will model laminated materials..... although if you use MATLAB, I don't think that FEMLab does. A number of the FEA companies have 300 node demo packages that you can...
  3. orangepeel

    Poisson's ratio greater than 1

    Dear all, Back to high Poisson's ratios.......RPstress mentioned "fishnet" stockings, or perhaps something like an onion sack. That may be similar to what I am trying right now. Anyone else tried a scissoring net like that for structural purposes? What kind of structural response...
  4. orangepeel

    need info on flexible material max 2mm thick

    Dear Oakies, I may be able to send you a sample, or you might be able to make it yourself, or if you are part of a university or aerospace firm, have them make it. My email address is kfldp00@tamuk.edu. I teach at a university... and am not in the commercial business. The scraps I have are...
  5. orangepeel

    hardness vs compound vs Elastic modulus

    For rubbers, what we call hardness is a measure of how deep an indenter is pressed into the rubber, given a certain force or energy... but when the indenter is removed, there is typically no permanent mark, as there would be for a metal. Hence, the hardness is a measure of elastic deformation vs...
  6. orangepeel

    polyurethane crack injection

    What type of polyurethane? Your best bet might be to find a large polyurethane manufacturer, and call their tech rep. Explain your problem, ask for their best product and tech sheets. The navy uses a lot of Adiprene L100 and other types for naval applications, under water....... for what...
  7. orangepeel

    Poisson's ratio greater than 1

    Simisastry, I am not aware of any such web sites for textiles, on the honeycomb question, you might have better luck posting it as a separate topic. I can't claim any significant expertise on deformed honeycomb structures.... Perhaps RPstress might be able to help. Good luck!
  8. orangepeel

    hardness vs compound vs Elastic modulus

    I believe that there are other postings here that discuss this, or the related question of correlating Shore A and Shore D hardness. In my opinion, there is a rough correlation between hardness, and elastic (initial Young's Modulus), but I would rather conduct some mechanical tests to be sure...
  9. orangepeel

    need info on flexible material max 2mm thick

    Oakies, Are you saying that you want the material to be stiff and rigid along one axis, and transverse or perpendicular to that axis, you want it to be very flexible? If you want something like that, I have something like it sitting on my desk. It is a laminate of graphite fibers and a...
  10. orangepeel

    Kevlar fibers in Rubber matrix?

    Onemorechance, No problem on the rules, ... just thought it would be a little faster to email directly back and forth, rather than come here and submit.... but this is more educational for everyone else. It appears to me that sharing email addresses is okay.... but ??... okay. Note: I...
  11. orangepeel

    Poisson's ratio greater than 1

    RPstress, Thanks for your help. I had looked at that (yours?) web site earlier and found it very interesting. I am looking to advance some theories for "solid" materials. My interest in high Poisson's ratios comes from my work with fiber-reinforced elastomers. The only solid...
  12. orangepeel

    Kevlar fibers in Rubber matrix?

    Onemorechance, Your design will not be as simple as it seems. If you just put axial or longitudinal fibers in your inflatable tube, the tube will contract axially under pressure, creating a "muscle". If you apply only circumferential windings, the tube will expand axially. The...
  13. orangepeel

    Composite material properties needed.

    Unless some supplier can help you, you will most likely have to conduct tests your self for those properties.... and there is not any FEA package that I know of, that will model laminated fiber-reinforced elastomeric materials, unless there are some very specific tire (cord-rubber) codes. I...
  14. orangepeel

    Composite material properties needed.

    Virtually none of those materials are isotropic, and most may have nonlinear material properties. I would be very surprised if your FEA package would even model a fiber-reinforced elastomer material. -ldp
  15. orangepeel

    Poisson's ratio greater than 1

    please pardon me, the above statement should read "I know that we can easily prove that for isotropic incompressible materials such as rubber, that the poisson's ratio can't be greater than 0.5". -ldp
  16. orangepeel

    Poisson's ratio greater than 1

    Dear all, I am looking for references, most likely relating to laminated materials, that discuss Poisson's ratios greater than 1. I'm especially interested in proofs on any type. I know that we can easily prove that for isotropic incompressible materials, that the poisson's ratio can't be...
  17. orangepeel

    Kevlar fibers in Rubber matrix?

    Onemorechance, I have done quite a bit of work with non-tire flexible composites or fiber-reinforced elastomers. a) It is possible to reinforce a rubber with Kevlar if you can get a compatible sizing on the fiber, and use the proper fabrication/processing method.... but I might suggest other...

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