Need a book? Engineering books recommendations...

# Re: "Analytical model"

• To: seaint(--nospam--at)seaint.org
• Subject: Re: "Analytical model"
• From: Alexander Bausk <bauskas(--nospam--at)gmail.com>
• Date: Tue, 4 Oct 2011 20:58:43 +0300

Hello Bill,
"right" is "richtig"; "rechen" is derived from rechnen, "(to) count".
I'm not sure about the German terms. It is essentially a bait to lure German listers to the thread (there are some AFAIK).

What I'm sure about is, we say something like "structural model", or "calculation model" to describe any generic formalized model of a structure.
Then, all sort of generic calculation models are, mathematically speaking, split into two domains: analytical and computational. You may clearly see this is a common scheme throughout many engineering and research disciplines by reviewing this search: http://goo.gl/FvHKt.

Analytical model has a closed form solution, that is, it can be solved in one iteration using the simplest operators. If your model is Y=f(X), you are usually able to retrieve the inverse solution, X=f'(Y), and express it in more or less simple terms.
In practice, any code check is deemed analytical and the common term used to humiliate junior engineers, the "hand analysis", usually redirects here (if you are not solving FE matrices by hand which is quite possible).

Computational model is usually highly iterative and includes complex procedures like FEA, boundary element analysis or CFD. It is still called analysis  of course (in your language). You cannot directly express X depending on Y in this case.

In other terms, your 15-minute-to-design ACI Excel spreadsheet calc is most likely analytical while any FE model is computational. These two models may actually describe the same structure like a pinned beam.
Any FEA software verification manual will host dozens of comparisons of computational vs. analytical models describing the same structures.

So yes, I think this is actually the most fundamental difference there is. And the current term usage disturbs me, especially when I see it propagating to masses on Autodesk venues and help materials (and they are darn good at help materials).

P.s. I'm sorry if I was getting too much narrative, that is just to be completely clear on the subject, I am clearly not qualified to lecture anybody on the list.

On Tue, Oct 4, 2011 at 6:46 PM, Bill Polhemus <bill(--nospam--at)polhemus.cc> wrote:
Is this a distinction recognizing a significant difference? Please explain.

(N.B. My "command" of German is limited to two undergrad semesters, but doesn't "Rechen„ have the connotation "right" or "correct"?)

On Oct 4, 2011, at 9:26 AM, Alexander Bausk <bauskas(--nospam--at)gmail.com> wrote:

Some clarification:
the difference is painful in our local case, because 'analysis' in sense of closed form and 'analysis' in sense of calculation are not homonyms in Russian. When localizing a software product, corporate style naturally enforces using translated terms as close as possible to the original. The result is devastating in sense of engineering culture.

This is also the case with other languages like German I think ("Analytische Modell" versus "Rechenmodell").

--
Alexander Bausk
Civil/Structural design & inspection engineer, CAD professional
MSc Structural engineering, Ph.C. Engineering
http://bausk.wordpress.com
ONILAES Lab at PSACEA
Dnipropetrovsk, Ukraine
Tel. +38 068 4079692
Fax. +38 0562 470263
bauskas(--nospam--at)gmail.com

--
Alexander Bausk
Civil/Structural design & inspection engineer, CAD professional
MSc Structural engineering, Ph.C. Engineering
http://bausk.wordpress.com
ONILAES Lab at PSACEA
Dnipropetrovsk, Ukraine
Tel. +38 068 4079692
Fax. +38 0562 470263
bauskas(--nospam--at)gmail.com