Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations TugboatEng on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Search results for query: *

  1. mlevett3

    Creating external superelement, but retain non-boundary nodes for plotting/visualization

    I have a cantilevered column type structure that I'm looking to reduce. I know I want the fixed boundary to be placed into the BSET, and to have enough spoints in the QSET, but I am confused on how to retain a select number of interior nodes and corner nodes (on the free end) that I can use to...
  2. mlevett3

    "Derived results" in FEMAP

    Ah, thank you. I had trouble finding the right topic to look at in the help manual.
  3. mlevett3

    "Derived results" in FEMAP

    Say you have done a linear static unit load and wish to output contours of some linear varying metric like strain at a multitude of loads. A quick way would be to just derive a result by multiplying the unit load's results by a scalar. In Hyperview you can do this very easy through "derived...
  4. mlevett3

    Physical meaning of generalized mass in normal modes?

    I think they may have been confusing generalized mass with modal effective mass. Part of finding effective mass is the general mass, right? Maybe they just meant that general mass helps lead to the effective mass.
  5. mlevett3

    Physical meaning of generalized mass in normal modes?

    I've always normalized so that the generalized mass is 1, but the Nastran lesson here (http://www.aerospacengineering.net/?p=2652) mentions that MAX normalization can lead to developing more intuition for what's going on based on the generalized mass. Can anyone explain what generalized mass...
  6. mlevett3

    BIW design

    I'd also recommend Automobile Body Structure Design by Malen. Covers much of the same "simple structural surface" technique as Brown, but also touches on some more crashworthiness and vibration considerations.
  7. mlevett3

    Shearlocking in fully integrated elements

    http://www.dynasupport.com/howtos/element/shell-formulations I've never used LS-Dyna, but I know selectively reduced integration can alleviate this. Isn't this page saying that Type 16 does that automatically? Or are "Type 16" and "Formulation 16" referring to different things? Selectively...
  8. mlevett3

    How many nodes/elements/DOFs do you work with?

    Don't worry GregL, I work on the order of 1000 nodes for a full automobile body. (concept model with mostly beams and very coarse shells)
  9. mlevett3

    Formula one car body and wings temperature at high speed

    Aerodynamic heating isn't a concern until much, much faster speeds. I used to study ultra high speed flight vehicles and I don't know if anybody thinks about aerothermodynamics til the hypersonic regime.
  10. mlevett3

    Maximum width to thickness before a stiffened element of a section elastically buckles?

    Just a coincidence on that half. They start from an empirical relationship for effective width, too.
  11. mlevett3

    Maximum width to thickness before a stiffened element of a section elastically buckles?

    Some sources, such as the AISI manual (http://scholarsmine.mst.edu/cgi/viewcontent.cgi?article=1059&context=ccfss-aisi-spec) use one of the many empirical formulas for effective width out there and set the effective width over the nominal width to 1 (because if it buckles in the elastic region...
  12. mlevett3

    Maximum width to thickness before a stiffened element of a section elastically buckles?

    I'm getting a contradiction in this book: https://books.google.com/books/about/Cold_Formed_Steel_Design.html?id=Bl2Ax7hNIIcC&printsec=frontcover&source=kp_read_button&hl=en#v=onepage&q&f=false When designing a section, say an I-beam, you'd determine the critical buckling stress from the...
  13. mlevett3

    Looking for an opensource "stick" model capable tool

    Don't know of any nonlinear ones, there's an excel linear one called 3DFrame, made by a user here.
  14. mlevett3

    3D Beam transformation matrix?

    Hey Doug, I've looked through your source code of 3DFrame and it seems like to me there's a discrepancy in the second and third row of the rotation matrix between that code (R0 array) and Saoma's notes (eq. 4.39) which you linked to. It repeatedly uses something proportional to...
  15. mlevett3

    3D Beam transformation matrix?

    So if I'm understanding correctly, the most efficient (least irritating) method of inputting sections for a user would be for them to provide the principle moments and then the rotation angle (alpha) of the principle axes from the horizon (XZ plane)? They should have all this information from...
  16. mlevett3

    3D Beam transformation matrix?

    Can someone explain the "alpha" angle in section 4.2.2.2 of the book IDS linked to earlier? That's a user input right? i.e. If I have beam I want to input and I know the orientation of the section in space, then how do I come up with alpha? I can see it has something to do with the angle...
  17. mlevett3

    3D Beam transformation matrix?

    Thanks both of you, the book is on order (I've seen it recommended often) and I've got the other materials until it arrives.
  18. mlevett3

    3D Beam transformation matrix?

    Anyone have an online resource for programming the transformation matrix for a 3D beam (or better yet, frame) element? I can only find one which omits the rotation of the axis along the beam to describe how the major and minor axes are defined.
  19. mlevett3

    2D Frame-Torsional Spring-Frame element model

    I'm doing this by hand, so what ended up working for me was to connect the frame nodes with a zero length, zero mass, extremely stiff connecting springs for both translational degrees of freedom and a flexible torsion spring with user inputted stiffness. Similar to the approach in Zuo, Li, Xu...
  20. mlevett3

    2D Frame-Torsional Spring-Frame element model

    I am trying to come up with the stiffness matrix for a 2D system of a frame-torsional spring-frame FE model to grow into a full 3D auto body "stick" model of frames and springs. In the past I've substituted the spring with a stubby beam of equivalent torsional stiffness for 2D, but I'd rather...

Part and Inventory Search

Back
Top