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  1. Francesco Bro

    Modal Participation Factor Meaning in Nastran

    Yes.
  2. Francesco Bro

    Modal Participation Factor Meaning in Nastran

    Thank you dmapguru for your response! Could you please help me by clarifying they difference of the MPF request in the Case Control? $ CASE CONTROL SECTION MEFFMASS(...,PARTFAC,...) = YES $ $ vs. $ PARTN=n
  3. Francesco Bro

    Modal Participation Factor Meaning in Nastran

    Hi nicomedian. I did, but it says nothing about the physical meaning, physical difference between MEM vs. MPF, industry standards, requirements, etc.
  4. Francesco Bro

    Modal Participation Factor Meaning in Nastran

    Hi all! We have been running modal dynamic simulations for an aerospace structural system, and I run into a basic, even tough tricky question: what is the physical meaning of modal participation factor (MPF)? What is the difference in terms of physical meaning with respect to modal effective...
  5. Francesco Bro

    MSC Nastran vs. NX Nastran in 2022

    I have been reading old posts in this forum from back in the 2004, 2005 regarding NX Nastran vs MSC Nastran capabilities. It is clear that on those times UGS had just gained access to the 2001 version of MSC Nastran original solver and started developing its own version. But what about in 2022...
  6. Francesco Bro

    Nodal stresses vs. Element stresses in Structural FEA

    Thank you all for the answers! I guess rolling back to my original question, it is not standard in the industry which stress value to look at for MoS computation (except NRP99 who mentioned nodal stress as the ultime value to take, assuming the FEA model has a proper mesh representation and the...
  7. Francesco Bro

    Nodal stresses vs. Element stresses in Structural FEA

    Hi, I am running into a structural verification criterion for an aerospace component, and as we know FEA packages offer the ability to show either nodal stresses and element stresses (at the centroid for instance). I realized that the nodal stresses values are much higher than the element...
  8. Francesco Bro

    Relationship of stresses vs. loads in linear analysis

    Let's assume we have the most general structural FEM model, which is being simulated with a classical linear FEA solution (no source of non-linearity is being considered). We know that if we run with load 1.0*P, 2.0*P, or even 3.0*P, we can predict deflections (displacements) will be the...
  9. Francesco Bro

    How to generate different OP2 output file for each subcase?

    Thank you DG! I am using NX Nastran (sad), so POST case control command has not been implemented in that solver. I guess I will go with the second option as a workaround. When you mention "no data recovery in the initial run for building the .MASTER/.DBALL database", do you mean no output...
  10. Francesco Bro

    How to generate different OP2 output file for each subcase?

    Hi, I have 3 different load subcases for 1G loads in X, Y and Z directions. I would need to have Nastran write 3 different different OP2 output files, one for each subcase. Is it possible? What case control cards should I use? For instance: == SUBCASE 1 ---> 1GX ---> output file: ...1GX.op2...
  11. Francesco Bro

    1-FEM-Element vs Analytical Solution of a Cantilever Euler-Bernoulli Beam - Theoretical Background

    Hi, Thanks to both for the prompt response! @FEA_way, if a 1-beam-element with 2 nodes is modeled, and the distributed vertical load is quadratic, the solution for displacement matches with the exact theory at the tip! My question was focused on the mathematical reason (provided that both...
  12. Francesco Bro

    1-FEM-Element vs Analytical Solution of a Cantilever Euler-Bernoulli Beam - Theoretical Background

    Hi, I have been reading simple example problems of FEM vs analytical solutions, and I run into a very simple (and maybe stupid) doubt which answer I couldn't find over days after searching in FEM textbooks! Let's assume we have a classical cantilever Euler-Bernoulli beam, clamped at the root...
  13. Francesco Bro

    Meaning of off-diagonal terms of the Rigid-Body Mass (MO) in the .f06

    We are checking out the mass of a model in Nastran (by using the WEIGHTCHECK or PARAM,GRDPNT commands), and the first mass matrix that appears on the .f06 print file is a M O, which looks like the 6x6 rigid-body mass matrix. We understand the meaning of the diagonal terms to represent the total...
  14. Francesco Bro

    How to suppress the CASE CONTROL ECHO in the .f06 output file?

    I would like to suppress the echo of the CASE CONTROL SECTION in the .f06 file, equivalent to suppress the BULK DATA SECTION by using the Case Control Command ECHO=NONE. Is there any way to do it? Any PARAM or config to set up? Thank you!
  15. Francesco Bro

    How to combine different output sets in the Case Control?

    I have different sets defined in the Case Control. My understanding is that output request variables are limited to only one SET, so my question is how can I combine multiple sets into a single one, and then reference this later one in the output variable? For instance: $* CASE CONTROL SET 1 =...
  16. Francesco Bro

    Difference between Grid Point Weight Generator and Weight Check?

    Hi, I know it is possible to check the mass properties and CG position of the FEM model by using the Grid Point Weight Generator (PARAM,GRDPNT,0). But it is also available the Weight Check command (WEIGHTCHECK) at the Case Control. What is the real difference between using one or the other...
  17. Francesco Bro

    Difference between defining PARAM in the Case Control rather than in the Bulk Data

    Hi, I am working with a Nastran input deck file directly. I saw it is possible to define PARAM (parameters) whether in the Case Control Section or in the Bulk Data Section. 1. What is the difference? Which section is better to define them? 2. Any recommendation of where to place them as per...
  18. Francesco Bro

    Define a non-uniform NSM distribution in a cylindrical shell in NX 11

    We are modeling a cylindrical shell with CQUADR elements. This shell contains several regions (along the axial dir z and theta sectors in a cylindrical CSYS) with different values of NSM. For instance: Region 1 0<z<10m 0<theta<90° NSM (2D=CQUADR)=1kg/m2 Region 2 0<z<10m 90°<theta<270° NSM...
  19. Francesco Bro

    Difference of modeling jointed bolts using CFAST vs CBEAM(CBAR)+RBE2 in NX / MSC Nastran?

    Hi SWComposites, bolt preload would be important to get pre-stiffening effects in the structural attaching zone, after bolt preloading.
  20. Francesco Bro

    What is the meaning of Coupled Load Analysis (CLA) for a Spacecraft?

    Hi, I would like to know the technical meaning of Coupled Load Analysis (CLA) for a spacecraft, mainly a satellite. Is CLA related to computer simulation (FEM) or testing? If you have any technical reference or textbook, I would really appreciate. Thank you.

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