In your response to my question about the lite FG over balse, you mentioned doing some stress analysis. I was wondering if you used a home-grown finite element code, or a commercially available product?

Webmaster's Note : Finite Element Analysis(FEA) is a numerical technique for simulating structures on a computer. The mathematical model can simulate a variety of realworld conditions, giving an understanding of how a structure (I.E. Wing) would perform. Typically, stress and deformations are "solved for".

From : Don Stackhouse

Chris,

I use the Algor Hypersap system for most of my Finite Element Analysis(FEA). I looked at COSMOS-M, even demo'ed it, didn't like it.Algor is much more user friendly and maneuverable, and allows you to investigate changes in the model in ways that aren't practical in the other systems I've investigated.

The key thing about FEA isn't so much the code, it's how you use it. You must have somebody who knows what they're doing supervising the entire process. I've seen stresses double or cut in half just by changing the mesh. The results normally cannot be taken entirely at face value, and you frequently must run several different mesh, load and boundary condition configurations to get the complete picture. The boundary conditions and loads are normally an approximate simulation at best, with lots of built-in simplifying assumptions, so you can easily generate all kinds of very thorough and professional looking results that actually have very little to do with the real life situation you thought you were modeling. You have to be constantly checking to make sure that your FEA model actually represents the real-life situation, which can be very difficult.

We generally try to use flight tests, static tests and FEA together to find the results, with each method acting as a guide and cross-check to the other two. FEA relied on by itself can be very dangerous! Be careful.

Don Stackhouse @ DJ Aerotech