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  1. rybose

    Puck criteria for Nastran

    The following reference lists some typical values. Knops, M. (2008). Analysis of Failure in Fiber Polymer Laminates: The Theory of Alfred Puck. Heidelberg: Springer-Verlag.
  2. rybose

    where is ANSYS 13 mechanical batch file located

    In V14 it's located here. C:\Program Files\ANSYS Inc\v140\ansys\bin\winx64\ANSYS140.exe The arguments to run in batch mode are a little complicated. Open the ANSYS product launcher to see the correct syntax for your setup. Go to Tools | Display Command Line. The command will look something...
  3. rybose

    Simply Supported Boundary Conditions

    In Nastran buckling you can specify two sets boundary conditions - one for perturbation (loading) and another for the buckling mode shape. This makes life a lot easier for the more complex cases.
  4. rybose

    Output Beam Local Coordinate System

    I am looking to output orientation vectors of beam elements to either the ODB or FIL. I have done this for shells using: *OUTPUT, FIELD *ELEMENT OUTPUT, DIRECTIONS=YES SF The local coordinate system shows up in the ODB in the fieldValue.localCoordSystem member. It also appears in the FIL...
  5. rybose

    Grumman Stress Manual?

    All curved panel shear stress methods that I've seen reference NACA TN 1348. Many NACA papers (TN 2661) reproduce the plots from this document.
  6. rybose

    Buckling Composite Curved Panel

    Looking for some methods to perform a buckling analysis on a composite cylindrical panel (simply supported on all edges). Most references for cylindrical shell buckling seem to implicitly assume a full cylinder. Whitney (Structural Analysis of Anisotropic Plates) has a solution for a curved...
  7. rybose

    Composite Analysis Software

    The commercial package HyperSizer does many of those things including CLT, stiffened and unstiffened panel buckling, and BJSFM. www.hypersizer.com
  8. rybose

    Closed Form Panel Buckling Solutions

    Definitely check out: Leissa (1985) - AFWAL-TR-85-3069 Buckling of Laminated Composite Plates and Shells I think it will have what you are looking for. Unfortunately, very few cases have neat closed-form solutions. The report does a good job of explaining why.
  9. rybose

    Eigenmode Imperfections - Postbuckling

    Is there any way in Nastran to apply geometric imperfections for a postbuckling analysis? In Abaqus, you can use the *Imperfection command to point to a results file of a buckling eigenvalue analysis. *Imperfection, file=buckle_results 1, 0.05 2, 0.05 .. (specify mode number and max...
  10. rybose

    NASTRAN COMMAND

    Learn to use a scripting language like Python. It's very easy to learn, and it has lots of built-in tools for the file management type things you are describing.
  11. rybose

    Ansys Advice

    trainguy - I stand corrected. Thanks. DHKpeWI - I'd recommend Niu's "Airframe Stress Analysis & Sizing"
  12. rybose

    Ansys Advice

    Generally speaking there are two ways to analyze instability (buckling) in FEA: linear eigenvalue analysis and geometric non-linear analysis. Linear eigenvalue analysis is typically the first step. It returns the buckled mode shape ("Euler" or local depending on which is more critical) and the...
  13. rybose

    cyclic symmetry in ALGOR static/linear analysis

    I recommend the book "Practical Stress Analysis with Finite Elements." It's not ALGOR specific, but it is essentially FEA for dummies.
  14. rybose

    Algor import question

    How do you plan on connecting the midplane mesh to the beams? As far as getting the 'skeleton' geometry into ALGOR from Inventor, this is something that I've spent a lot of time trying to do. I haven't found an automatic way to do it. The best workaround I've found is to: 1) In Inventor, place...
  15. rybose

    Water tightness errors really bug me. Any easy way to solve these?

    If you say you have a "frame" you should be using beam elements. Period. I've tried to mesh a welded tubular frame with shell elements and wasted 3 weeks trying to get the meshing to work. It never did. In the end it was the wrong approach anyway. I assume that when you say "tubes in...
  16. rybose

    Parsing FIL file with Python

    The reason I want to get away from the ODB is that you have to have ABAQUS/CAE open to access it. I find this a little cumbersome. I am writing some utilities to analyze post-buckling of stiffened panels. The models are generated as Nastran files from another code. I am trying to do the pre...
  17. rybose

    Parsing FIL file with Python

    Hello all, I am looking to access the .FIL file instead of going through the .ODB. The Abaqus documentation says that each entry is 8 bytes long whether it's a string, float, or integer. I am trying to used the struct module to convert the binary. I am unsure what format to use to read 8 byte...
  18. rybose

    Conversion of Time History to Response Spectrum

    www.vibrationdata.com It will cost you $40 for the subscription, but it has plenty of simple programs in matlab and C++.
  19. rybose

    How to create a 2d geometry in inventor for Algor

    Right click the face in Inventor, then select "Export Face As..." This will let you save the face geometry as a .dxf which can be imported directly into ALGOR as construction lines.
  20. rybose

    Shell elements

    Sorry I wasn't clear in my original post. Like GBor said, turn off all of the surfaces except the ones you'd like to mesh with plates/shells. If you try to mesh a part with no surfaces "selected for meshing", the mesher will give you an error just like you said.

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