Hinges under stress - mechanical engineering type question

"Corrie" wrote in message
om...
john wrote in message
. ..
On 30 Jul 2003 16:56:37 -0700, (Corrie) wrote:

"MS20001P aluminum hinge is extruded. The closed hinge loops cannot be
pulled apart. Furnished with hinge pin. Anodized finish."

Thanks. How much stress can it take, though? That's the question.
Probably the hinge pin or the rivets holding the plates would be the
first to fail at a few hundred pounds, but still... musing I
suppose one could order some and find out.... If the specific alloy
were known, it could be looked up.
http://ourworld.compuserve.com/homep...orhis/T003.htm shows
yield and tensile strengths for a number of allows. They tend to be
around 30kpsi. The catalog doesn't give the thickness of the flange.
Assume it's .1", and the hinge is 6" long, that's .6 sq. in, at
30kpsi.. 18,000 lbs? But some alloys are as low as 5kpsi - that's
3,000 lbs. Impressive for a small hinge, but would it suffice for the
application? Marginal at best, I think.

The largest hinge at AS&S is just 2" wide, and they all seem to have
the same size pin - .089 stainless. That's .006 sq. in. area. I
can't find a reference for shear strength for stainless, but taking an
optimistic SWAG at 200kpsi (the highest yield strength for drawn ss
referenced at
http://ourworld.compuserve.com/homep...orhis/T006.htm),
that's 200,000 x .006 = 1200 lbs. Not nearly good enough. /musing


My guess is that if it's not specifically rated and labeled, it's
unknown. Not something to put in a critical area. So, then, back to
the original question. Assuming you don't have the ability to extrude
a larger piece of aluminum (in order to use a larger pin), how *do*
you solve the problem?

Like this:

http://www.zenithair.com/kit-data/ht-aileron.html

Rick Pellicciotti

For the people that didn't visit the Zenith link, thats a sheet metal
hinge, no moving parts, just flexing sheet. I've seen this up close
and its pretty slick. One of those "Why didn't I think of that!" kind
of moments.

Regards

"Rick Pellicciotti" wrote in message news:3f298016$1@ham...

Like this:

http://www.zenithair.com/kit-data/ht-aileron.html

Rick Pellicciotti

"Jay" wrote in message
om...
For the people that didn't visit the Zenith link, thats a sheet metal
hinge, no moving parts, just flexing sheet. I've seen this up close
and its pretty slick. One of those "Why didn't I think of that!" kind
of moments.


I'm concerned about corrosion on such a flexing member and how the
imperfections introduced could concentrate stresses during flexing and cause
premature failure.

"Peter Gottlieb" wrote in message
. net...

"Jay" wrote in message
om...
For the people that didn't visit the Zenith link, thats a sheet metal
hinge, no moving parts, just flexing sheet. I've seen this up close
and its pretty slick. One of those "Why didn't I think of that!" kind
of moments.


I'm concerned about corrosion on such a flexing member and how the
imperfections introduced could concentrate stresses during flexing and
cause
premature failure.

Corrosion protection is critical on any metal airplane part. If you read
the dissertation on the web page, Chris Heintz goes into a lot of detail on
how they tested it for fatigue and they even damaged it intentionally and
tested it.

Rick