Autodesk ForceEffect bicycle simulation

We interrupt the usual endless helmet discussion for a brief tech
interruptu

Please go thee unto:
https://forceeffect.autodesk.com
or go directly to the bicycle frame example at:
https://forceeffect.autodesk.com/frontend/fe.html
or try the video:
https://www.youtube.com/watch?v=xlGUKh9gxt4 (4:26)

It's quick and slick for calculating the forces on various structures,
including bicycles. It's not FEA, but it still looks useful.

Hint: Try right mouse click at the various nodes, objects, and blank
areas.

There's an "experimental" external gearbox:
https://forceeffect.autodesk.com/frontend/help/en/gear_box_external.html
but I can't seem to make it work with the bicycle model. Maybe I
should read the instructions.

18 YouTube Videos:
https://www.google.com/search?q=force+effect+autodesk&tbm=vid

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Monday, April 11, 2016 at 6:56:00 PM UTC-4, Jeff Liebermann wrote:
We interrupt the usual endless helmet discussion for a brief tech
interruptu

Please go thee unto:
https://forceeffect.autodesk.com
or go directly to the bicycle frame example at:
https://forceeffect.autodesk.com/frontend/fe.html
or try the video:
https://www.youtube.com/watch?v=xlGUKh9gxt4 (4:26)

It's quick and slick for calculating the forces on various structures,
including bicycles. It's not FEA, but it still looks useful.

Hint: Try right mouse click at the various nodes, objects, and blank
areas.

There's an "experimental" external gearbox:
https://forceeffect.autodesk.com/frontend/help/en/gear_box_external.html
but I can't seem to make it work with the bicycle model. Maybe I
should read the instructions.

18 YouTube Videos:
https://www.google.com/search?q=force+effect+autodesk&tbm=vid

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

an eternal gearbox !

off Broadway biology

http://www.nytimes.com/2016/04/12/sc...e-of-life.html

On 4/11/2016 6:56 PM, Jeff Liebermann wrote:
We interrupt the usual endless helmet discussion for a brief tech
interruptu

Please go thee unto:
https://forceeffect.autodesk.com
or go directly to the bicycle frame example at:
https://forceeffect.autodesk.com/frontend/fe.html
or try the video:
https://www.youtube.com/watch?v=xlGUKh9gxt4 (4:26)

It's quick and slick for calculating the forces on various structures,
including bicycles. It's not FEA, but it still looks useful.

Pretty amazing. I (vaguely) remember working through FEA problems by
solving the matrixes by hand - for simple cases, of course. Then later,
using tedious software, choosing element types, coordinates etc. very
deliberately and typing in proper values.

One thing I don't get about that bicycle example: When he applies the
load at the seat, he doesn't have a reaction in place from the
spring/shock unit. Seems to me that makes the structure unconstrained.
Something in the software must tell it to not change the internal
geometry (yet), but he didn't make that clear.

On related matters: I once read a science fiction story, describing a
society in the far future. Certain professions had lost all their
status because of technology. For example, doctors were a dime a dozen,
because you could take anyone off the streets, give them a device
smaller than an iPhone, and have them dictate a patient's symptoms into
it. The device gave the diagnosis and told the proper treatment.

I hate to think of mechanical design going down that path. But I guess
judgment will always be necessary. For example, one tricky part of FEA
is specifying the proper support reactions. At the headset reaction,
many people wouldn't think to apply a roller or "sliding support," and
would put in a fixed pivot point instead.


--
- Frank Krygowski

On Monday, April 11, 2016 at 8:08:21 PM UTC-4, Frank Krygowski wrote:
On 4/11/2016 6:56 PM, Jeff Liebermann wrote:
We interrupt the usual endless helmet discussion for a brief tech
interruptu

Please go thee unto:
https://forceeffect.autodesk.com
or go directly to the bicycle frame example at:
https://forceeffect.autodesk.com/frontend/fe.html
or try the video:
https://www.youtube.com/watch?v=xlGUKh9gxt4 (4:26)

It's quick and slick for calculating the forces on various structures,
including bicycles. It's not FEA, but it still looks useful.

Pretty amazing. I (vaguely) remember working through FEA problems by
solving the matrixes by hand - for simple cases, of course. Then later,
using tedious software, choosing element types, coordinates etc. very
deliberately and typing in proper values.

One thing I don't get about that bicycle example: When he applies the
load at the seat, he doesn't have a reaction in place from the
spring/shock unit. Seems to me that makes the structure unconstrained.
Something in the software must tell it to not change the internal
geometry (yet), but he didn't make that clear.

On related matters: I once read a science fiction story, describing a
society in the far future. Certain professions had lost all their
status because of technology. For example, doctors were a dime a dozen,
because you could take anyone off the streets, give them a device
smaller than an iPhone, and have them dictate a patient's symptoms into
it. The device gave the diagnosis and told the proper treatment.

I hate to think of mechanical design going down that path. But I guess
judgment will always be necessary. For example, one tricky part of FEA
is specifying the proper support reactions. At the headset reaction,
many people wouldn't think to apply a roller or "sliding support," and
would put in a fixed pivot point instead.


--
- Frank Krygowski

how specify a roller or sliding support for one moment or a curve of moments ?

On Mon, 11 Apr 2016 20:08:19 -0400, Frank Krygowski
wrote:

On 4/11/2016 6:56 PM, Jeff Liebermann wrote:
We interrupt the usual endless helmet discussion for a brief tech
interruptu

Please go thee unto:
https://forceeffect.autodesk.com
or go directly to the bicycle frame example at:
https://forceeffect.autodesk.com/frontend/fe.html
or try the video:
https://www.youtube.com/watch?v=xlGUKh9gxt4 (4:26)

It's quick and slick for calculating the forces on various structures,
including bicycles. It's not FEA, but it still looks useful.

Pretty amazing.

Yep. I hadn't seen it before. Then I noticed that the YouTube videos
were made 4 years ago. I don't think I was asleep at the wheel for
that long to have missed it.

I (vaguely) remember working through FEA problems by
solving the matrixes by hand - for simple cases, of course. Then later,
using tedious software, choosing element types, coordinates etc. very
deliberately and typing in proper values.

I was lucky and got into matrix arithmetic at a time when computahs
were beginning to do the dirty work. In electronics, there was plenty
of matrix math, but nothing on the scale of FEA.

One thing I don't get about that bicycle example: When he applies the
load at the seat, he doesn't have a reaction in place from the
spring/shock unit. Seems to me that makes the structure unconstrained.
Something in the software must tell it to not change the internal
geometry (yet), but he didn't make that clear.

Hmmm... good point. At least the 3 forces show equal zero.

If you move the mouse to the weird symbol under the "Save" button, it
will complain about "Overcontrained State" and then proclaim that you
can run the model anyway. It's not very clear if the resultant
calculations are correct. Offhand, I would guess(tm) that the shock
absorber (section G - J) is being treated as a solid member but really
needs some kind of sliding joint in order to move.

On related matters: I once read a science fiction story, describing a
society in the far future. Certain professions had lost all their
status because of technology. For example, doctors were a dime a dozen,
because you could take anyone off the streets, give them a device
smaller than an iPhone, and have them dictate a patient's symptoms into
it. The device gave the diagnosis and told the proper treatment.

Brings back fond memories of BITE (built in test equipment) and
computer diagnostics. I just saved a friend a few hundred dollars in
auto repair costs by ignoring the advice of the OBD-II diagnostic, and
going with the much cheaper wisdom found in various web forums. I've
had the same problem when trying to choose between an expensive
failing catalytic converter, and a much cheaper oxygen sensor.

The problem with such systems is that they can easily be programmed to
lie, cheat the end customer, and cover their tracks. They can also be
programmed to provide all the possible faults resulting in an
expensive repair, instead of drilling down to the exact cause. That
can result in such recommendations as "replace engine", which is
effectively useless. Expanded to include medicine, it can favor the
doctors by recommending high priced surgery, or the insurance
companies by recommending delaying treatment until the patient dies.

For automobiles, we're there today. If you go to any of the dealers
to do repair, you'll soon find that they no longer have any resident
experts or specialists. What they have is a diagnostic computer, that
sends the diagnostic results to the factory, where a central computah
grinds the symptoms, and provides the mechanic with a list of probable
culprits. The dealers and factory consider this a good way to do
things because they can't afford to train an army of competent
mechanics, who will probably go into competition with the dealer as
soon as possible anyway. The price we pay for this is the
proliferation of sensors and computahs in the vehicle, most of which
are no more reliable than the mechanisms they are monitoring.

I hate to think of mechanical design going down that path.

It will happen. Like the automobile repair biz, it won't be because
computer diagnostics are necessarily better. It will be because
education is more expensive, and computerization is a cheaper
solution.

It's happening in automotive design today and is largely responsible
for such abominations as having to remove spark plugs through the
wheel well, and inaccessible fittings. Someone takes a computerized
model of automotive sub-assemblies, sticks them together on a computer
screen, does some checking, maybe makes a model, and sends it off to
be assembled. The first article usually has a zillion problems, but
those are hammered to death on the computer. Eventually something
emerges that can be sold. Why bother doing it like this? Because the
name of the game is NOT to produce a better automobile. It's to
produce an automobile that complies with a zillion regulations, codes,
standards, and guidelines. Already, many cars in the same performance
class are starting to look almost identical. Dragged to its logical
extreme, the buyer of the future will have a choice of colors and
service contracts, but little else. Ossification by regulation.

But I guess
judgment will always be necessary.

Judgment is a linear quantity. There can be various levels of
judgment applied. The common adage "you can't add quality by
inspection" applies here. Unless the design is correct, no amount of
judgment, inspection, regulation, or rework is going to produce a
quality product.

For example, one tricky part of FEA
is specifying the proper support reactions.
At the headset reaction, many people wouldn't think to apply a roller or
"sliding support," and would put in a fixed pivot point instead.

The bicycle model already fails that requirement. The bicycle hits
the ground at two points (front and rear wheels). This would add too
much complexity to the example, so it was ignored. When hitting the
ground, there can be only one of these points pinned to the ground.
The other has to be on rollers so that the frame can flex and the
suspension can flex. However, the designer picked the wrong wheel.
Since the front wheel receives no power from the drive train, it
should be the one that is pinned to the ground, while the rear wheel
should have rollers, with an added force perpendicular to the ground
in order to move the bicycle forward. In other words, the supports
are backwards.

I really should get back to doing my taxes...

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Consider the tax code as a factor, the factor as the path the path as the way thru the jungle.

On Mon, 11 Apr 2016 20:08:19 -0400, Frank Krygowski
wrote:

On 4/11/2016 6:56 PM, Jeff Liebermann wrote:
We interrupt the usual endless helmet discussion for a brief tech
interruptu

Please go thee unto:
https://forceeffect.autodesk.com
or go directly to the bicycle frame example at:
https://forceeffect.autodesk.com/frontend/fe.html
or try the video:
https://www.youtube.com/watch?v=xlGUKh9gxt4 (4:26)

It's quick and slick for calculating the forces on various structures,
including bicycles. It's not FEA, but it still looks useful.

Pretty amazing. I (vaguely) remember working through FEA problems by
solving the matrixes by hand - for simple cases, of course. Then later,
using tedious software, choosing element types, coordinates etc. very
deliberately and typing in proper values.

One thing I don't get about that bicycle example: When he applies the
load at the seat, he doesn't have a reaction in place from the
spring/shock unit. Seems to me that makes the structure unconstrained.
Something in the software must tell it to not change the internal
geometry (yet), but he didn't make that clear.

On related matters: I once read a science fiction story, describing a
society in the far future. Certain professions had lost all their
status because of technology. For example, doctors were a dime a dozen,
because you could take anyone off the streets, give them a device
smaller than an iPhone, and have them dictate a patient's symptoms into
it. The device gave the diagnosis and told the proper treatment.


Errr... I believe that such systems are already in use. Log in, enter
the symptoms and you get an answer of the most likely cause and any
additional possible causes in descending likelihood of occurrence.
And, of course, a recommended course of treatment.



I hate to think of mechanical design going down that path. But I guess
judgment will always be necessary. For example, one tricky part of FEA
is specifying the proper support reactions. At the headset reaction,
many people wouldn't think to apply a roller or "sliding support," and
would put in a fixed pivot point instead.
--

Cheers,

John B.

On Tue, 12 Apr 2016 19:13:43 +0700, John B.
wrote:

Errr... I believe that such systems are already in use.

Yep. It's a hypochondriacs paradise:
https://www.google.com/#q=online+medical+diagnostics

Log in, enter
the symptoms and you get an answer of the most likely cause and any
additional possible causes in descending likelihood of occurrence.

I can see you haven't tried or done any telemedicine. Unfortunately,
I have and find the current state of affairs to be marginal but
improving steadily. The big problem is that the average user is not
sufficiently medically literate to supply or understand the necessary
buzzwords needed to describe a problem. Examples on request. The
diagnostic results are also problematic. For output, the system
offers a wide variety of possible ailments, most often without any
rankings or probability. I tried three, found only one that offered
probabilities, and none that provided which symptoms were used to make
the determination. Then, there's the patients understanding of the
results:
https://www.math.hmc.edu/funfacts/ffiles/30002.6.shtml

And, of course, a recommended course of treatment.

None of the three I tried offered any recommended treatments. However,
that was about a year ago and things may have changed. I suspect that
lack of such recommendations might be to avoid being accused of
practicing medicine without a license.

Of course, if online medicine did work and attracted substantial
interest and revenue, the AMA will see to it that it's banned. That's
what happened in California a few years ago, when the legislature made
it illegal for patients to order their own blood tests without a
doctors autograph. The logic was that patients are unable to
understand the results of these tests and require a doctors
interpretation and involvement. There are ways around this:
http://www.directlabs.com
but I'm sure if online diagnostics is successful, it too will be
banned.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Online medical diagnosis games probably a substitute for reading n thinking. shortcut to basic understanding.

You're ahead. if the online diagnostics cut a path down the middle of the current run of physicians