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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...

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

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...

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.

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...

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.

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...

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)

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.

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

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...

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...

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

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...

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...

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...

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.

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.

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...

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...