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  1. johnhors

    USER Fatal error 2106

    You have used 100 twice as a load set identification number. try changing LOAD 100 1. 0.04968 100 to LOAD 200 1. 0.04968 100 (assuming 200 is not already used !) www.Roshaz.com quality, cost effective FEA solutions
  2. johnhors

    ANSYS modal analysis and normalization methods

    Drej - nodal displacements are simply just that. There is no nodal averaging for displacement results. Elemental results are calculated using the nodal displacements as one of the inputs. From "element nodal results" you can get stresses and perform averaging on the stresses of course, but not...
  3. johnhors

    ANSYS modal analysis and normalization methods

    Your mode shape looks very symmetric. I suspect the values at top and bottom are the same to within round off error limits, thus both locations qualify for the maximum value and numerical round off determines which one gets it. It is not a calculation error. You should ask ANSYS why some of the...
  4. johnhors

    FEA for Bridge Analysis

    look at this perhaps? http://www.lusas.com/products/bridge_tour_overview.html www.Roshaz.com quality, cost effective FEA solutions
  5. johnhors

    difference between Elemental and element nodal?

    Dare I say it, but your "norm EN280" was either written by people with little or no understanding of FEA or more likely it is not in fact a guide on how to build and run your FEA. Does it just describe the contribution from the mass of persons in a free body diagram? As Blas pointed out...
  6. johnhors

    Shell Elements Assembly - VALUABLE QUESTION

    Cylindrical or cartesian coordinates, what difference that does make to the element? You have specified 4 node quadrilateral elements, which can only have straight edges, the shape functions of which are defined by the element geometry and not by any coordinate system used in node location. As...
  7. johnhors

    Bearing Ball FEA simplified modelling

    Chris H. a couple of points, firstly your post has moved away from the simple 1D approach to a full 3D modelling effort for the bearings. (each ball bearing was modelled with a single spring or gap element with earlier posts). Secondly, having ventured into the 3D modelling world, the "spoke"...
  8. johnhors

    Nastran Format - Family Names.

    1. I don't think you can do this. But you can specify element sets. 2. you change the number of columns from 8 to 16 by using the * format, for example:- GRID* PSOLID* PSHELL* Items in fields 2 to 9 occupy 16 columns. Line length must not exceed 80 columns so you have to use continuations...
  9. johnhors

    Change licence path

    Isn't the license locked to the server? Why aren't you talking to the Abaqus help desk about this? www.Roshaz.com quality, cost effective FEA solutions
  10. johnhors

    FEA meshing - why not 2d mesh -> 3d mesh ???

    Backing up what Julian and rb1957 have already said, FEA is just a tool, a very powerful tool that should only be used by competent stress analysts. By competent I mean someone who is capable of producing a hand calculation to accompany their FEA has a sanity check. The stress analyst will...
  11. johnhors

    Inexpensive FEA software

    Just to add a little to what Brian has said, Abaqus uses .inp "input files" and can also use python script files to control the analysis, the script file does not contain model data. Other programs like Lusas use a "data file" with extension .dat But every FE analyst knows (or should know)...
  12. johnhors

    Inexpensive FEA software

    "deck" is an old fashioned name for an input file for a FE solver. In the early days of FEA you would type out your model data one line at a time onto a piece of card. You would end with a large pile of cards, as with playing cards these were referred to as a "deck" of cards or card deck. A...
  13. johnhors

    Nauseating aircraft vibration...on the ground

    "Lemme guess, Airbus product?" - if it had been an Airbus product then the engines would have been CFM , which are 50% US anyway! Boeing 757 only uses Rolls-Royce engines - a UK product ! Boeing or Airbus, they are international products and have been that way for many many years! I have...
  14. johnhors

    zero pivot error in the msg file/abaqus

    Try running a modal analysis. This will identify any rigid body modes with zero (or very near to zero) frequencies, the mode shapes of which will give a visual representation of any under constrained mechanisms in the model. www.Roshaz.com quality, cost effective FEA solutions
  15. johnhors

    Help Writing Subroutine

    Your code starts with "PROGRAM MAIN", but this main routine ends with a RETURN statement, that is not correct. You assign double precision values to ZERO,ONE,TWO,and THREE, but double precision has not been declared for these or any other variables. Many variables like C10, C01, C11, C20, C30...
  16. johnhors

    Seat Track - Boundary Conditions

    You should be using a free body diagram with each component to determine what forces to apply to them. From that you can then decide how to support the model. www.Roshaz.com quality, cost effective FEA solutions
  17. johnhors

    Modelling Rock using Drucker Prager Model

    "So stress & deformation values are same for both metal & rock with the same geometry?" vtmike, I think all that Terio was stating was that 1 square inch of ANY material subjected to 1000 lbf load will have a compressive stress of 1000 psi for equilibrium (assuming the material can withstand...
  18. johnhors

    Solid element with integration points co-located with corner nodes

    "usage of thin shells on top of exterior faces of solids gives more accurate results than extrapolated results on solid faces" - no they do not, "skinning" a solid model will not yield more accurate results. The quality of the results is determined by the quality of the solid model alone, you...
  19. johnhors

    modal analysis

    "What's the difference between natural frequency and modes?" - each mode has a mode shape and an associated natural frequency (the eigenvector and eigenvalue). You are performing modal analysis of the structure as a whole, there is no such thing as a "main-activator". The eigen solver does not...
  20. johnhors

    Solid element with integration points co-located with corner nodes

    "Seems like there is one in Abaqus" - really! what is it called? What's wrong with using results extrapolated on to a surface from the integration points? Assuming the mesh is sufficiently refined (mesh convergence) then the error induced by extrapolation will be negligibly small...

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