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Recent content by craigj

  1. craigj

    abaqus rubber compression and surface strains help!

    step 1 first. - What is the material you are modeling, and what model are you using? You should be using a hyperelastic one...right? Do you have material data? What modes of strech do you have? Marlow is a stable model, but only uniaxial data and calculates the other modes. - What element...
  2. craigj

    Nonlinear Column Buckling

    If youre really brave you can try a nonlinear static simulation using the arc-length method as the iteration scheme. This will allow you to accurately identify the stiffness = 0 point of the curve (i.e. buckling point). This method is not for the faint of heart and is normally reserved for...
  3. craigj

    SIlicone overmolding

    Interesting stuff. Thanks for the tip.
  4. craigj

    SIlicone overmolding

    Does anyone have a handle on an injectable grade silicone rubber that will stick to a polycarbonate alloy substrate (insert molded)? Wanted in black... Thanks craig
  5. craigj

    spring rate for NBR and CR rubbers

    testing is essential depending on your application. Sometimes testing cost does not pay off! I have done simulations with both fully tested materials and also with a linear approximation and guess what...it didnt matter. What Im trying to say is that some thought must be given to what you want...
  6. craigj

    Gasket calculation procedures

    basically your clamping pressure has to be greater than the pressure you are trying to withstand. For this you will need general material proprties and understand your geometry. Normally I use 25-35% comprerssion for most rubber type seals as a nominal value. 1. Pick a material 2. Assume a...
  7. craigj

    intersting materials site

    this is a cool site for polymer material model comparisons http://www.polymerfem.com/index.php thats it, Craig
  8. craigj

    ABS characteristics in low temp service

    Actually my understanding is that polycarbonate is the most impact resistant material by itself (most energy absorbtion, even at low temp). The reason that ABS is added to PC is for molding purposes (it flows nice). Different companies use different amounts of each for their alloys. Fun stuff...
  9. craigj

    Prototype Encapsulation and Sectioning

    Thanks very much for the input!
  10. craigj

    ABS characteristics in low temp service

    Nigel, The reason their curves start at 53C is probably because that is the transition temperature. I did find a reference for Cycolac T (ABS) As you would expect your yield actually goes up by 50% Flextural yeild @73F = 10,500psi Flextural yeild @-40F = 15,600psi Probably a bigger concern...
  11. craigj

    Looking for FEA Text references

    I like "Finite element modeling for stress analysis" by Robert Cook. Easy to read... If you are very technically minded you could go for the bible: "finite element proceedures in engineering analysis" by Bathe
  12. craigj

    Prototype Encapsulation and Sectioning

    Cory and Mike, Yes RTV would be a bad choice...I wasnt thinking. Thanks for the hints and the name of the process, you both have been very helpful. Cheers CJ
  13. craigj

    double sided adhesive

    Try the 3M website (eg. 3m9731) . People do it all the time...depends on the gasket/seal material (ie. silicone, epdm, etc). CJ
  14. craigj

    on rubber dynamic stiffness

    http://www.mscsoftware.com/support/library/conf/auto00/p04500.pdf Ansys also has a good nonlinear code :P There is a test lab called datapointLabs that might be worth checking into. http://www.datapointlabs.com/ Axel products is also, as you know from a previous reply, a good testing lab...
  15. craigj

    Prototype Encapsulation and Sectioning

    Dear Group, I would like evaluate a new plastic prototype assymbly by cutting sections in the product so that I can see how internal parts are mated. Someone told me of a method where you cast (encapsulate) your prototype in an clear RTV resin. Once it has dried you take a diamond saw and cut...
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