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  1. nvhuser

    Harmonic loading definition

    Hello guys, I have found a pretty good video that shows how to define a dynamical load using ABAQUS/GUI: Link https://www.youtube.com/watch?v=RP3t9Ge8BCw The duration is about 3 minutes and it explains it very quick - it might help!
  2. nvhuser

    Surface normal vector orientation

    Hi Gutboy17, do you have access to ANSA pre-processor? If yes, I can help you to create the "pressure loads" through the normal vector of the elements surface (that should point outwards).
  3. nvhuser

    Violated and Active Responses - Nastran Optimization

    Hi everyone, I have some questions regarding violated and active responses. As attachment to this post there is a excerpt of f06 file of an optimization cycle. There are 4 DRESP2 Responses, all of them have an upper bound of 0.19. If you look to the top, you can read the following...
  4. nvhuser

    Welding Aluminium - NX Nastran

    Hola Blasmolero! Thank you very much for your reply, in fact CWELDs are very useful connectors - indeed, I use them quite often in some seat models. My perception is in the company that I am working for they want to avoid the usage of this kind of connectors, sometimes if they have the same...
  5. nvhuser

    DESVAR Versus DCONSTR - Nastran

    Right JXB0809, I will avoid these practices [bigsmile]
  6. nvhuser

    Welding Aluminium - NX Nastran

    Hello everybody, I have some experience creating the FE models for the spot welds of steel structures like body-in-white (normally I use RBE3-CHEXA). Now, I am working for a new company where the body-in-white has some aluminium parts. Should it be expected a difference in the modelling of the...
  7. nvhuser

    DESVAR Versus DCONSTR - Nastran

    Hi Tuw, thank you for your reply. I agree with you, I am little bit concerned about increase the number of DCONSTR from 2 to 20, but probably there is no big difference in computational time.
  8. nvhuser

    DESVAR Versus DCONSTR - Nastran

    Hello guys, generally in an optimization problem what would increase more the simulation time, increase the number of design variables (DESVAR) or increase the number of constraints (DCONSTR)? Looking forward your feedback. Thanks
  9. nvhuser

    Hammer Test - Frequency Response Analysis

    Hi JoshPlum, you are welcome. I think this is the purpose of this forum: to learn with the community and have fun ;)
  10. nvhuser

    Hammer Test - Frequency Response Analysis

    Hi JoshPlum, thank you for your link, I will ask my manager to buy it for me. Thank you for your suggestion!
  11. nvhuser

    Modal Assurance Criterion - MAC

    Hello everyone, does anybody have experience using MAC? Could anyone explain me what is the importance of having the AUTOMAC coefficients for a given structure? I know that AUTOMAC can give the insight about how good is the node pair table used, but do you know any other aspect that is...
  12. nvhuser

    Hammer Test - Frequency Response Analysis

    I read the book from Ewins (Imperial College London) - Modal Testing, and he describes there the circle fitting method. However, Nyquist plot for a MDOF model unfortunately presents "poor circularity". I think it is difficult the modes there. Also the peak picking method to determine the normal...
  13. nvhuser

    Hammer Test - Frequency Response Analysis

    Hi JoshPlum, thank you for all your excitement during this quest! It is good to see people committed in FRF analysis :) Sure, this is really an academic problem, IDEAS is very popular to do this kind of stuff, but sadly I don't have a license available. Could you send me the link where I can...
  14. nvhuser

    MATLAB - Complex Mode Indicator Function

    Hello, can anyone explain me how this script works? Tool in Matlab to extract the modal parameters from FRF data (Complex Mode Indicator Function - CMIF): http://www.mathworks.com/matlabcentral/fileexchange/9476-cmif-complex-mode-indicator-function/content/jzcmif.m
  15. nvhuser

    MATLAB - Symbolic variables are not working

    I have a small task to perform and the command “syms k m c” doesn’t work. If you have any idea why doesn’t work, please let me know.
  16. nvhuser

    Hammer Test - Frequency Response Analysis

    Hi, I have some acceleration curves measured by a test-engineer (the data available consists into Magnitude and Phase). Currently, I would like to have a list of the normal modes (eigenfrequencies). So, the question is: how to extract the normal modes using FRF-experimental data? Since I have a...
  17. nvhuser

    Harmonic loading definition

    Hello, I am new using ABAQUS, could anybody help me how to define a dynamical load using GUI or through editing a inp file? Thank you
  18. nvhuser

    Fluid-Structure interaction - MSC Nastran

    Hello, I am doing some acoustic simulations using MSC Nastran and the perturbed models consist often into some modifications in the doors and body-in-white (mainly, meshing tasks). The cavity model remained untouched. So, as result of these modifications, the SET1 of elements for the command...
  19. nvhuser

    Conversion NASTRAN to ABAQUS

    Hello everyone, I am trying to perform a simple frequency response analysis using ABAQUS - using a 2-DOF model Here is the NASTRAN inputdeck: ID FRF_TWO_DOF SOL 111 CEND TITLE = TWO-DOF SYSTEM SUBTITLE = MODAL FREQUENCY RESPONSE LABEL = NASTRAN EXAMPLE $ SPC = 996 METHOD = 10 DLOAD = 999...
  20. nvhuser

    Basic FRF questions - Abaqus

    Hello everyone, I am attempting to generate some FRF plots in Abaqus to be able to compare to experimental data taken with an impact-hammer/accelerometer (unv file). My questions are: 1 - Which step should I use? "Direct-solution steady-state dynamic analysis"? 2 - How should I define the...

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