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Recent content by pbd999

  1. pbd999

    CBUSH elements with non-coincident nodes

    You will have to decide if it would change the results in the fastener loads and if that change is meaningful, but I thought it might help to give my thoughts on this topic, which I find is a question that comes up pretty often where I work. It might be helpful to compare CBUSH to CELAS...
  2. pbd999

    Any NEi Nastran tension only shell element experience?

    I was wondering if anybody has experience using the NEi Nastran tension only shell element. It has been a common challenge at the aerospace companies I have worked at to properly idealize the buckled behavior of thin aircraft skins and panels in a finite element model, especially at the vehicle...
  3. pbd999

    Linear Buckling Solution

    I can give only the basics...it can get complicated and is so problem dependant. Instead of Sol 101, call out Sol 106. In the Subcase section you need to call out the NLPARM from the bulk data section. Use PARAM, LGDISP,1 to turn on large displacements. You have to have an NLPARM card in the...
  4. pbd999

    Linear Buckling Solution

    Nastran Sol 105 will give you the linear buckling load, but when you have a beam column (eccentrically loaded column) the real failure load will always be less than the linear buckling load. The linear buckling equation includes the stress stiffness matrix (MSC calls it the differential...
  5. pbd999

    CTRIA3 Elements

    I asked someone at MSC this question and here was his response, "The CTRIAR element is exactly the same as the CTRIA3 element except for the drilling dof (rotational component of motion normal to the plane of three connecting grid points) of the element, hence this makes it a constant strain...
  6. pbd999

    CTRIA3 Elements

    I don't think the CTRIAR is a linear strain element. The way I understand FEA theory is that with only 3 nodes available to create the shape function, you get a constant strain element. The CQUADR and CTRIAR are better than the old standbys CQUAD4 and CTRIA3, but the biggest difference between...
  7. pbd999

    ANSYS Resource on the web

    Just wanted to tell you all that there is a new web site that has been set up as a resource for ANSYS users. There are quite a few ANSYS white papers, an FAQ and some tutorials all available on the site. You don't need to register or anything.... http://ansys.belcan.com Paul
  8. pbd999

    Press fit

    Martin, You can certainly do this in Workbench...I have done it many times. When you bring in the geometry ANSYS will automatically define the contact pair, that is the "Contact" and "target" surfaces between the parts. By default this will be a bonded contact condition but if you select the...
  9. pbd999

    Non-symetric laminate

    Does anyone know how Nastran calculates the MID3 transverse shear properties that go on the associated MAT2 card? I realize that you could leave this blank if you were creating the equivalent PSHELL by hand, but Nastran creates it for every PCOMP/MAT8 layup.
  10. pbd999

    Calculation of MAT2 properties from PCOMP

    When modeling a composite laminate using MSC.Nastran the PCOMP and MAT8 (or MAT1) entries are converted before the run to an equivalent PSHELL and four MAT2 entries which are used in the actual Nastran run. I understand that three of these MAT2 cards are calculated from classical lamination...
  11. pbd999

    Inventor & Ansys vs Solidworks & Cosmos

    Inventor works very well in conjuction with the ANSYS Workbench Environment (for lower end linear type analysis this is also known as DesignSpace). You can launch ANSYS from inside Inventor and your part or assembly will be automatically imported. The ANSYS Workbench GUI is very intuitive, it...
  12. pbd999

    Ansys Books or Tutorials

    Go to Amazon.com and search on "ANSYS Tutorial". There is a book available from Kent Lawrence. I don't have it but I got it from the library once and it was good. Good website from the University of Alberta in Canada: http://www.mece.ualberta.ca/Tutorials/ansys/

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