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  • Users: MBD26
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  1. MBD26

    ExcelVBA error: "License Not Found"

    I've been using excel to run ESRD StressCheck through its COM API interface. Never had any issues with this, works just fine. I recently had a standalone "spinoff" program called StressCheck ToolBox installed, which has a similar COM API but with its own object library. The library is recognized...
  2. MBD26

    Nastran Post-Buckled Analysis of Thin Plates

    I'm working with a thin (.040) rectangular panel in an airframe that easily buckles under shear and goes into diagonal tension. The panel is bolted down to frames/stringers on all four edges. I've got a 2D breakout Nastran model of the region detailed down to the fastener level with cbushes, and...
  3. MBD26

    Joint Stiffness Calculation, Clearance v. Neat v. Interference Fit

    I have an aircraft longeron/frame splice with a mix of neat-fit and interference-fit fasteners. Typically, we calculate fastener stiffness for our FE models using the Grumman equations lap joints. However, looking at the theory and the test data the equations are based on, it doesn't look like...
  4. MBD26

    Simple API for View Options

    Awesome, much appreciated. And thanks for taking the time to comment, that helps a lot
  5. MBD26

    Simple API for View Options

    Does anyone have a simple API script for turning on Node IDs (only Nodes) that they'd be willing to share? Complete novice to API, and having some trouble with the syntax. That would be a huge help. Many thanks
  6. MBD26

    Modeling joint bearing+pulloff

    I'm correlating results to a finding on a fatigue test article. Need the KtS at the hole and the stress gradient for crack growth. Al 7050 plate.
  7. MBD26

    Modeling joint bearing+pulloff

    Hello all I'm working a joint on an aircraft former flange that has some significant pull-off load, in addition to bearing/thru. I'd like to model this with a solid fem, using either NXCAE or stresscheck. I have detailed solid geometry of the former with the fastener hole modeled, and I'm...
  8. MBD26

    Honeycomb panel, 2D mesh

    I’m attempting to model a honeycomb core panel in Patran. The top surface is composite cloth, core in the middle, and the bottom is composite tape. I’ve heard this can be modeled using a 2D-3D-2D element sandwich approach, but this is for an internal loads model and I’d like to simplify things...
  9. MBD26

    Nastran Linear Contact validation

    Running linear contact in Nastran, and thinking of things that need to be checked to verify that I've got good quality results. Obviously you should check the f06 to make sure it even converged, and then plot contact stresses to make sure load is coming through in a way that makes sense. Is...
  10. MBD26

    Nastran max disp, max spcforce output

    That did it. Thanks Blas!
  11. MBD26

    Nastran max disp, max spcforce output

    In a Nastran deck, what controls whether or not the tables of max displacements and max spcforces gets written? I have two runs. One has these tables, the other doesn't. Trying to figure out why the second one doesn't
  12. MBD26

    CBUSH elements with non-coincident nodes

    I have two parts (a skin and an aircraft former flange) overlapping with a row of fasteners along the length of the overlap modeled with CBUSH elements. The parts are modeled with CQUADs, and are slightly offset, such that the CBUSH elements have non-coincident nodes (though the CBUSH elements...
  13. MBD26

    truss structure normal modes: low frequencies?

    Greg is actually pretty close with the space station comment... I'm modeling a UAV in flight, so it's an unconstrained model. I've since learned that, for an unconstrained model, it makes sense that the first 6 modes would be 0Hz rigid body modes. I'm not familiar with the nuances of modal...
  14. MBD26

    truss structure normal modes: low frequencies?

    I have a 3D solid model of a truss, and I'm using Nastran to determine the normal mode frequencies. Nastran is giving me results for modes 1-10. The first 6 modes are effectively 0 Hz, but my understanding is that those correspond to rigid body translations and rotations and that 0 is the...
  15. MBD26

    Propeller-induced structural vibration and normal modes

    To simplify the situation I'm trying to model, imagine you have a cantilever beam with a propeller oriented perpendicular to the length of the beam at the free end. I want to ensure that the prop vibration won't excite any of the normal modes of the beam. If I run normal mode analysis on the...
  16. MBD26

    Constraint set for accelerating aircraft?

    jhardy, I think that's exactly what I'm looking for. Thank you!
  17. MBD26

    Constraint set for accelerating aircraft?

    Because you need constraints to run FEA. Maybe I should have been more clear... the aircraft is the body. I want to know what the peak stress in the airframe is due to this vertical acceleration. If you don't constrain the model, you just get rigid body motion and the model flies off into space...
  18. MBD26

    Constraint set for accelerating aircraft?

    I'm trying to wrap my head around what a reasonable constraint set would be for an accelerating body. I have a helicopter that will be accelerating upwards, and the acceleration load will be applied to the entire body. I'm struggling with the idea that I would just apply a typical 3-2-1...

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