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  1. NicolasJobert

    how to make use of the results of ADINA or ANSYS in FORTRAN?

    ANSYS can be used as a simple executable using line commands such as ansys -I My_Input_File.txt -O My_Output_File.txt It has also a langage of his own (called APDL) that you may use to calculate whatever property you need. Good luck
  2. NicolasJobert

    MSC Nastran CELAS1 strain energy

    antti, I had the same problem with a 2 dof system (CMASS + CELAS2), running a static analysis. All data but the Element Strain Energies (ESE) are correct. This 'ESE' bug disappears when running a modal or transient analysis, so I guess that my FE-model is correct. Guess what ? Never trust a...
  3. NicolasJobert

    OROS or PULS system

    Hello there, I recently made a 3 days training for a Honda team, "hands on experimental modal analysis". I did not know about OROS before that day, (only used to old HP or BK analyzers), but on the overall it ran smoothly. This was a 16 channels systems with 5 ICP 3D accelerometers...
  4. NicolasJobert

    Low frequency (1hz) displacement from acceleration

    Stephen as Greg said, double integration is hardly an option. I have tried it myself a few times (also with a BK 2635 charge amp vs non contact optical devices) and the results kept being very poor, although I used many analog/signal processing tricks in order to improve the whole process. If...
  5. NicolasJobert

    vibration in hollow cylinder

    Hello, here is my two cents on the subject, namely how to take into account the fluid contained into the cylinder. Pure mass addition should yield correct results as long as dilatationnal (acoustic) waves in the fluid have a wavelength much longer than the structural wavelength: This is for...
  6. NicolasJobert

    Dynamic Impact Force from falling object on pavement

    Hello there, your question may be answered in a simple way, if your beer keg behaves in a perfectly elastic linear way (which I seriously doubt). With that assumption made, the contact time will be equal to the very simple formula: time=pi * sqrt(m/k) where: m equals the "dynamic...
  7. NicolasJobert

    FE code for complex eigenvalues

    Hello there, as far as I know, ANSYS and NASTRAN can perform such analysis (I have used both), but probably some other FE code can do it also. Depending on the application, there may or may not be a shortcut to avoid you the expense of such programs (I have long worked on damping structures...
  8. NicolasJobert

    Fluide-Structure Interaction using ANSYS

    Hello there, does anyone has an example of running a simple Fluide/structure interaction with ANSYS ? I sucessfully performed some purely acoustic computations (baffled circular piston, pulsating sphere, and so on) and the numerical results compares fairly well with the analytical solutions...
  9. NicolasJobert

    ground vibration - course

    Hello OKdB, You need to carry out 2 kind of computations - predict the vibrations transmission in the building - predict the sound radiated by this vibrations in a particular room. A rough answer to your question will be found in the "Structure Borne Sound" (Cremer, Heckl, Ungar)...
  10. NicolasJobert

    Frequncy response vs time response analysis

    elogesh, using direct transient analysis or using the more sophisticated approach ... using FFT time => frequency using harmonic analysis solve for response using IFFT frequency => time ... should yield exactly the same result ! (FFT approach may be much more economical on some occasions.)...
  11. NicolasJobert

    Fluid Structure Interaction

    Joe, I suggest that you post your question on this forum, which is dedicated to Nastran: http://lists.dundee.net/cgi-bin/lyris.pl?enter=msc.nastran&text_mode=0&lang=english Anyway, if you have some clear and simple examples of fluid-structure interaction problems solved with Nastran, I would...
  12. NicolasJobert

    Results listing

    Did you try putting your results in a parameter (*vget) and writing it to a standard FORTRAN File (*vwrite) ? Nicolas
  13. NicolasJobert

    How can I define variable material properties?

    Can you elaborate a little bit on that, more precisely, your modulus of elasticity will be variable with respect to what ? To load your model with a static sinusoidal shape, the simplest way should be to store the nodes to be loaded in an array, then use their coordinates (using NX, NY and NZ)...
  14. NicolasJobert

    Does "Component Mode Synthesis" mean "Craig Bampton" substru

    Hello there, I am a new MSC/NASTRAN user (formerly ANSYS, sigh .... :-)) I have to make numerous minor modifications to a huge model (our customer requested that), and recompute its dynamic behaviour for each new version. Thus I would like to use the "Craig Bampton" substructuring...
  15. NicolasJobert

    Random Vibration transmissibility

    Indeed, the only question is, is your data MOTION transmissibility or FORCE transmissibility ? If it is the first case (which is highly likely), you can get you output PSD simply by multiplying the input PSD by transmissibility. If it is not the case, the you can convert you force...

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