"Richard Smith" wrote in message
...
Hi again Gunner, and anyone else who wants to join in...

So this thread - it's more of analysing structural performance -
strength / stiffness / load-bearing.

Something I find really exasperating here, in the UK. Is the same
in
the US?
You opinion?
I think that with
* CNC plasma / laser cutting
* press-braking with a lot of software guidance
* high-strength tough thin plate
* highly-controlled welding - even if manual (GMAW processes)
* CRUCIALLY - Finite Element Analysis modelling easily done
you can make much higher performing structural assemblies from
plate, not assemblages of sections - various angles, box-sections,
etc. - for much nigher-performing steel fabrications.
Much stiffer, much more load-bearing to weight, well-predicted
fatigue
resistance at high cyclic loads, etc.
Fairly-much - make in welded steel (cheap) for ad-hoc
machine-chassis,
etc., to overall design strategy of riveted aluminum aircraft
sub-assemblies (expensive).
Finite Element Analysis enables you to know under design loads the
stresses, deflections and likely fatigue resistance of the proposed
design which the fabricator "details" to the overall specification
of
the component.
The thinking is so conservative here and there seems to be not a
single person in any engineering / leadership (none of that - is
"management") role with whom you can talk the absolutely obvious.
I spent about 30 days busting my brain around how to use a Finite
Element Analysis package, and went from zero to being show the
falacies in shoddy work with no effort put in by contracted-in
engineering consultants.
If you know FEA at all - "shell elements" enable you to model thin
plate structures very readily and economically. It is very
difficult
to make a design for a single component which will take more than a
minute of a current personal computer's time to solve.

I did a web-page about this concept
http://www.weldsmith.co.uk/skills/fe...-fold-stl.html

It's so exasperating that what is obviously and readily done by
someone working "on the tools" is invisible by reason of
unfamiliarity
to most in "leadership"...

It seems that there is a "lazy" assumption that progress is only
being
made in "leading" endeavours like computing, bio-whatever and so on,
and no-one but those on-the-tools can see there's similar levels of
advancement possible in "traditional" (sic.) endeavours, as the
overall technological advancement lifts the "baseline" of what is
readily possible.

Thoughts?

As a lab manager tasked with turning Ph.D's paper concepts into
working hardware I noticed a divide between those who were really good
with higher math and those who could visualize the workings of a
machine or circuit. I can look at a truss and see which elements are
in tension or compression but one of my physics teachers couldn't, he
had to look for the sign of the force vectors, even for a simple
triangular street sign support. OTOH I ran into a brick wall trying to
understand Laplace Transforms and the s plane in college, where math
was taught as an art form. Fortunately a chemist doesn't need it.
Later I took electrical engineering classes in night school, taught by
working engineers who used math to solve real-world problems, and
their explanations of applying complex number theory to AC and RF
circuit problems were MUCH easier to follow. This time instead of
nearly flunking I aced Differential Equations and AC Circuit Analysis.
Finally I could read the display on a vector network analyzer and know
what to change to improve the circuit. In FEA terms that's like
finding an unexpected stress riser.

Simulation is easier in electronics because measurements are less
intrusive and the failures aren't destructive. It was pretty good at
describing something that had already been done before, not so good at
predicting into unfamiliar territory. For that we had to build, test,
and adjust the sim and hardware models iteratively.

Here's a classic example of a failure caused by a mathematical model
that was too difficult to implement:
https://en.wikipedia.org/wiki/Hyatt_...lkway_collapse

The original design of the tie rods required the threads to support
only one level, the rods' solid cores bore the weight of the walkways
below. The redesign left the top level's threads and nuts additionally
supporting the lower level.