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  1. hootrpootr

    Using INCLUDE files to run two model configurations in one

    I'm fairly inexperienced with Nastran INCLUDE files, but I'm hoping I can use them for an analysis I'm running. Basically I have an assembly with various panels, brackets, fasteners, etc and I'm trying to set up my model so that it contains two configurations. Both configs will be set up in...
  2. hootrpootr

    Fastener joint modeling using single RBE2 instead of CBUSH w/ "spider" RBE2

    Hello, I have a question I was hoping you all could answer. A coworker sent me an FE model that he created, where he modeled a bolted joint using just an RBE2 element (with DOFs in 123) to connect the matching holes in 2 plates. I would never do this; my preferred modeling method would be to...
  3. hootrpootr

    Patran Results: Shell Force, Force Resultant - von Mises quantity vs. force magnitude?

    Thanks FEA way, but does this also apply to shell forces? What is a Von Mises "Force" extracted from a shell element?
  4. hootrpootr

    Patran Results: Shell Force, Force Resultant - von Mises quantity vs. force magnitude?

    Hello, If the title is confusing, let me explain. I'm trying to extract loads from a Patran shell model in the x and y directions. I could just separately extract the x and y components of the shell forces, but I noticed there is a quantity called "von Mises". I know that von Mises stress is a...
  5. hootrpootr

    Tension clip (Tee section) resolution of forces?

    So then would it be reasonable if I sized the tee section based on the resultant force R? Thanks
  6. hootrpootr

    Tension clip (Tee section) resolution of forces?

    Thanks for the response! I should have stated that the drawing attached is not to scale, sorry. In reality, it is as you would expect, thinner. I see what you’re saying. I’d overlooked the moment M. But would that moment M exist somewhere at the center of the tee section (where the web and...
  7. hootrpootr

    Help with sizing of lug attachment flange

    Thank you for the response r13! But for step 2, wouldn’t Fz be the force component that creates a torque at the center of the bolt group, not Fy?
  8. hootrpootr

    Help with sizing of lug attachment flange

    Hello, Apologies for the crude drawing attached, but here goes. Given Fx, Fy, and Fz loads applied at the lug hole, I've distributed the loading into each of the 6 fasteners to size them. I've also sized the lug itself using the airforce lug sizing method. But now I'm trying to size the...
  9. hootrpootr

    Ansys Norton creep power law constants?

    ...creep constants, specifically C1, C2, and C3 for the Norton Power Law. I understand that the equation is usually shown in 2 ways: epsdot = A * (sigma^n) * (t^m) or epsdot = A * (sigma^n) * exp(-Q/RT) Which form does Ansys use? I can’t seem to find an answer in any of the manuals or...
  10. hootrpootr

    High cycle fatigue analysis: Performed fully in FEM or partly in FEM and partly in Excel?

    Mustaine3, what are the benefits of using specialized codes to determine the fatigue life as opposed to determining it within FEM? Or in other words, why would one prefer having to extract FEM results for an external calculation over keeping all the work within one program (FEA)? Thanks
  11. hootrpootr

    High cycle fatigue analysis: Performed fully in FEM or partly in FEM and partly in Excel?

    Are the results from a fully FEM analysis typically realistic enough to accept with confidence, as a static analysis would?
  12. hootrpootr

    High cycle fatigue analysis: Performed fully in FEM or partly in FEM and partly in Excel?

    I’m trying to wrap my head around different ways of analyzing a components high cycle fatigue life, since I’m now just learning that FEM software is (supposedly) able to perform fatigue analyses, given I set up the model correctly. At my company, the method I was taught was to run two static...
  13. hootrpootr

    3D Bolt Load Distribution Spread Sheet

    ...by Px, Py, Pz 6. Determine fastener distance components (dx, dy, dz) from centroid 7. Calculate the r^2 components at each plane, and the sum(ak*r^2) at each plane 8. Determine the components of each fastener of the forces at each plane due to rotation 9. Add the linear and rotational...
  14. hootrpootr

    Stress Concentration: Hole in infinite thin plate loaded in biaxial tension vs biaxial compression

    ...the loading to put the plate in compression, and received the exact same Kt. I can't seem to find anything in the book or online about the biaxial compression case. Is this true? *The screenshot comes from Table 6-1 of FORMULAS FOR STRESS, STRAIN, AND STRUCTURAL MATRICES 2nd Edition by Pilkey
  15. hootrpootr

    Is AUTOSPC the same as “Automatic constraints”?

    Thanks dmapguru! That makes perfect sense. You seem to have a deep understanding of Nastran, so I was wondering- could you possibly help answer another question I have? Not sure if this violates posting by asking here, but do you understand what the use of a .pch file is? If it contains...
  16. hootrpootr

    Import Nastran .pch file that contains DMIG information (stiffness matrix?)?

    First of all, I’d like to apologize for any misleading information or confusion I may cause, as this is a topic I’m very unfamiliar with. Basically, a customer provided me with a set of files with which to create and run a model using Patran with Nastran. All of the files except one make...
  17. hootrpootr

    Is AUTOSPC the same as “Automatic constraints”?

    The title seems pretty self explanatory, but the automatic constraints check box is located in “solution type” —> “solution parameters”. And if I wanted to enable AUTOSPC through the .bdf, would that just be going to the PARAM section and adding a line for “PARAM AUTOSPC YES”? I can’t seem to...
  18. hootrpootr

    Moment/stress caused by the bending of bushing flange

    Hello, I'm checking the bending of a bushing flange, where a high axial force (along axis of bushing) is essentially pulling the bushing through a hole and causing the flange to "kick up". How would I determine the moment and stress caused by the load? I'm thinking, what if I convert the...
  19. hootrpootr

    Single shear bolt shear and moment diagrams

    Thanks for both of the responses. After looking through TR-12 I was able to find some figures that resemble my drawings (slight differences because of different assumptions, etc). WeezerMike, if it’s not too much to ask, I’d appreciate hearing your thoughts in more detail. I know that I did...
  20. hootrpootr

    Single shear bolt shear and moment diagrams

    Hello, I’m trying to determine what the shear and moment diagrams of a bolt in single shear look like. Before anyone says it, I know that it’s rare that a bolt will ever fail first in bending, and this is something that typically isn’t even checked for. Anyway, I’ve assumed that the bolt is...

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