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Recent content by jetmaker

  1. jetmaker

    Joint efficiency factors

    Anyone got a public domain resource on the joint efficiencies of staggered vs inline fastener patterns for lap joints in metallic structures? Thanks
  2. jetmaker

    Cold Work vs. Shot-Peening

    There are many reasons to pick one over the other. Most are based upon what is most suitable to do from a practical standpoint. I am not sure how the depth of the compressive layers differ for each method. However, data (proprietary) which I have seen indicates that a cold-worked hole is...
  3. jetmaker

    Matrial Bearing vs Compressive Yield Stress

    I would have though compressive yield would be more conservative than bearing yield as bearing allowables are often higher than straight compressive yield. As to your question tho, if weight is not an issue, then I would be conservative as many other factors can play a role in your final lug...
  4. jetmaker

    Question on the definition of Limit Load and service life

    Interesting discussions. Not sure I follow where the OP was going with this, but the original question about limit and service load work this way for me. A limit load is a once per lifetime load. Aircraft must not suffer permanent detrimental deformation. Service load is not a FAR...
  5. jetmaker

    Extracting element stiffness matrix for MAT9

    Looking for some help here. I have a composite laminate in which each ply is represented by a layer of solid elements. There are 8 plies total, with the stacking sequence being [0/45/-45/90]s. A generic MAT9 card is used. When the property field is assigned, a material CID aligned with the...
  6. jetmaker

    Current Financial Mess

    Hah... The banks would be happy if they made 80/20 loans. Read that some were making 105% loans on expensive homes to cover closing costs. There were some smart people that played the game the same as the banks were... they got 105% loans on million dollar homes and then did not make a single...
  7. jetmaker

    Current Financial Mess

    The financial mess is alos a produce of the media. They hype it up and make people panic. That in turn cause more panic and a downward spiral insues. The bailout (no refered to as a rescue package) is flawed. If the gov't buys all these bad debts, then the taxpayer is saddled with all these...
  8. jetmaker

    7050 Plate Lug Curves

    bf109g, I ran into a similar problem. There is a Boeing document which covers these materials, although the document is proprietary. I only mention it as I do not know whom you work for. The alternative is to use the cutoff curves for aluminum alloys, thus ensuring you are as conservative as...
  9. jetmaker

    Freeze Plug retaining strap.

    MrHiLok, If the stack up is fitting, T-Chord, panel, then if the freeze plug is confined to the T-Chord, no retention is required as it is trapped between the fitting and the panel. Another option is to use a countersunk freezeplug with the csk side between the fitting and the T-Chord. This...
  10. jetmaker

    Connecting Parallel Plates Without Bolts, Welding, or Epoxy

    What about dovetailing the parts together??
  11. jetmaker

    Equal Biaxial Testing Lab

    Contact the NRC-IAR lab (National Research Council of Canada - Institute for Aerospace Research). Many years ago they had a groovy biaxial testing machine. jetmaker
  12. jetmaker

    Short Edge Margin

    If your loading direction is parallel to the short edge distance, then you actually have a short end margin. You will take a hit both in bearing and shear/tearout. Likely tearout will govern if the material is thick enough to develop full bearing initially. In this condition, static loading...
  13. jetmaker

    Equal Biaxial Testing Lab

    Try the National Research Council of Canada - Institute for Aerospace Research, up in Ottawa. They had a biaxial test frame many years ago. jetmaker
  14. jetmaker

    Limit Loads & SCFs vs Ultimate Loads

    Noor, Do not disagree with you, however, that is a local failure and in fact, does not truely constitute a failure in my mind. Bolt hole yielding is not critical unless the joint is a critical single path, limited bolt number joint. In fact, it is often important to have yielding around bolt...
  15. jetmaker

    Limit Loads & SCFs vs Ultimate Loads

    Be careful tho, because the ignoring of SCF at ultimate load is conditional upon the material being ductile, of large net section, and static loading. Another note is that designing to limit load is not typically the critical condition for most materials used in aerospace as the ratio of yield...
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