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  1. groveri

    safety margins for composites

    Do aircraft companies that use damage tolerant strain allowables (eg. open hole) for composites use maximum limit loads to calculate safety margins or do the loads have safety factors included in them. Like MS = Damage tolerant strain allowable for the laminate/max limit load strain -1.
  2. groveri

    film adhesive bond strength

    I'm designing/analyzing a carbon/epoxy filament wound aluminum lined pressure vessel with a film adhesive bond between the line and composite. I have a region of high adhesive shear, remote from the edges so the bond is in transverse compression (no peel stress) due to the internal pressure...
  3. groveri

    water absoprtion

    I have a material datasheet with a property called "Water Absorption" with value of 0.70% at condition of 50% GH/EQ. I'm not familiar with the term GH, I assume EQ is equilibrium. Can anyone explain the meaning of GH and what the 0.70% value means? The datasheet also has "Moisture Absorption"...
  4. groveri

    material coordinate system

    I have an abaqus model translated from another code with axisymmetric solid orthotropic elements. In the original modlel the orthotropic material properties were relative to the edged defined by the forst 2 nodes. In the translation, the reference to the element edge was lost and the...
  5. groveri

    isotropic vs kinematic hardening

    Thin metal liner performance in filament wound pressure vessels is enhanced by autofrettage of the liner. The pressure vessel is loaded beyond the yield strength of the liner so that the liner is compressed when depressurized. The liner will then have a larger elastic range to operate in...
  6. groveri

    COSMOS/M installation - Windows 7

    Since I bought it from SRAC and SW bought SRAC, I guess SW is my reseller. I contacted SW licensing and they are not interested in helping. So I guess if I can't solve the problem on my own, I'll just have to keep an old XP PC if I want to continue to use cosmos. Thanks for the advice though...
  7. groveri

    COSMOS/M installation - Windows 7

    Yes, it is becoming a relic, but I have a lot of time invested in some specialized Macros, and I know how to get around most of the program issues you have with any software. Plus, I own it and it doesn't cost anything, all of the reasonable options are a lot of $. I think it can work on 64 bit...
  8. groveri

    carbon steel strain hardening

    I'm doing an FEA of a carbon steel line composite pressure vessel with fully reversed plastic loading during the autofrettage cycle. I have the elasto-plastic stress-strain data, but I'm looking for guidance for hardening during the compressive part of the cycle following the initial tension...
  9. groveri

    COSMOS/M installation - Windows 7

    I have a permanent cosmos/m license I've use for 5 years w/ Windows XP w/ dongle. Tried to install on new Windows 7, 64 bit machine. New machine recognizes dongle, but not licence file. Any tips?
  10. groveri

    axisymmetric analysis with asymetric loads

    I may be solving my own problem, I found a good description in the COSMOSM BAsic System Documentation that might show me the way. Would still appreciate any samples.
  11. groveri

    axisymmetric analysis with asymetric loads

    I'm trying to do a simple 1 element static linear asymmetric load analysis of an axisymmetric PLANE2D element model (COSMOS/M 2008) which requires us of the A_ASYM command. The COSMOS documentation is pretty weak on the subject. I apparently get a successful run, but the results are null. My...
  12. groveri

    low temperature fatigue of hdpe

    I'm looking for fatigue data for hdpe at about -45C (-50F). Seems to be a lot of data at and above RT, but little at low temperatures. Can anyone help?
  13. groveri

    buckling of cylindrical shell in compression

    Hansmeister - Would it be possible to get some details on the SCI liner buckling - vessel diameter & length, liner material & thickness, composite material and thickness, autofrettage pressure, description of buckle (picture if possible), etc. I also have done work for SCI. Can you give me a...
  14. groveri

    buckling of cylindrical shell in compression

    Haven't had time to think about prex's remarks, I've been on extthended travel. I think I might disagree with remark one. The energy state before and after buckling is for small deflections and the amplitude of the bucklle waves can be arbitrarily small. The axial compression is just the...
  15. groveri

    buckling of cylindrical shell in compression

    Prex, I did think about the radial reactions, but decided they don't affect the energy solution (see Timoshenko in my initial question) I used because they do no work and thus do not enter into the energy balance. As for the friction, remember that my cylinder is a pressure vessel liner, and...
  16. groveri

    buckling of cylindrical shell in compression

    ...mode shape will produce a reasonable approximation of the critical load. For the symmetrical buckling of Timoshenko’s problem, he used -sin(m*pi*x/l). I used (1-sin(m*pi*x/l)), which is always greater than 0, for a shell that is constrained from outward deformation by external contact with...
  17. groveri

    buckling of cylindrical shell in compression

    The last homework I did was 28 years ago. Engineers actually do this kind of stuff. I planned on using this method fro a much more complicated problem. Anyway, I answered my own question so I don't need a response. I'll try to figure out how to end this topic.
  18. groveri

    buckling of cylindrical shell in compression

    I'm trying to derive eq. (f) in Timoshenko's Theory of Elastic Stability, 2nd Ed. Article 11.1, p. 458. Its for the increase in strain energy during symmetrical buckling in a cylindrical shell. I've got the 1st and 3rd terms, but for the 2nd term, (piA^2Ehl/2a), I have a Poison's ratio squared...
  19. groveri

    high strength ball joint

    I need to make a ball joint as small as possible, so I need to use a high strength steel. The ball has an integral threaded shaft. The max tensile load is 60% of the max compressive load. Temperature is <200F, >-100F. Life of part is short - few high loads. I'm looking for suggestions for...
  20. groveri

    fiberglass g10

    Thanks sreid and panelguy. Form the links supplied I found enough to back calculate some details. Based on densities. it looks like 40% to 50% fiber volume. Based on stiffness and strength it looks like balanced 0/90 weave, no of angle plies.

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