HPR Strength of Materials Study
Drake
whole are a great bunch of people. I have been a lurker for some time now
and have been only just recently been asking a few questions. Many of you
have been helping me for a while and don't know it. I want to repay you
guys.
Who am I? My friends call me Doc. I am the Chief Metallurgist and Laboratory
Director at The Scranton Army Ammunition Plant. And thus, this is how I can
repay the HPR community.
I have seen much debate over "this glue is better than that" or "this glue
is better for this material than that" and even brands and or cure time.
I have a $750k materials testing machine (OK it's the Army's but its mine to
do with as I please). I can test the strength of materials in tension,
compression, shear and even cyclic fatigue (fin flutter). I can test at any
temperature liquid nitrogen to 800 (+/- 0.01 F) degrees F. I can test forces
up to 55,000lbs with an accuracy of +/- 0.00015 lbs. All reported values are
NIST traceable and all of my dimension measuring equipment is traceable to
the Army's Rock Island Measurement Labs. (+/- 0.0000005")
What I propose is this:
Come up with a HPR strength of materials test. It could be tensile strength
of shock cords, the compression strength of various airframes, tensile
strength of glued substrates or something. We could glue pieces of Bud Nosen
wood together or various shock cords or anything (within reason) else. The
key is to have everything the same except for the test subject. Only one
variable. Dimensions aren't that critical because the result will be
force/(sq/area)/time/distance. What needs to be the same are things like
ply's in wood or type of wood, accuracy of measurement ratios of epoxy,
fillets or no fillets.
First we need to decide weather or not this is worth everybody's time. Does
anyone care? The second thing we need to decide on is what to test. I think
the most versatile (and mostly debated) is various glues.
Once decided, I will need all of us to make the test samples. The more
tests, the more accurate the results. I will then test the samples and
publish all of the data. I can put it up on my webpage or anywhere else we
decide.
I suggest we test CY, all speeds and brands of epoxy, and wood glue on wood
to wood. Each person could make three samples, from three batches of glue.
The results can include, tensile strength, yield strength (at any strain),
modulus, shear strength, compressive strength, fracture toughness, fatigue
crack growth or any mechanical property you can think of. I can also then
report the hardness (Rockwell) of the glue and the mode of failure
(brittle/ductile).
OK, Let the comments, suggestions, and flames fly.
Drake "Doc" Damerau
Jim Meyers
construction materials. For example, what is the strength of a JB-Weld, West
Systems, ZPoxy, etc bond on aluminum, QT, phenolic etc.
--Jim
NAR# 77786 L2/TRA# 8361 L2
"Drake" <mo...@sprynet.com> wrote in message
news:9vcrtk$arn$1...@nntp9.atl.mindspring.net...
Witless
experience aerated adhesives are significantly weaker. However, my observations
are based on bulk epoxies rather than thin film applications.
Since a faucet vacuum pump is under $10, removing the dissolved air from
adhesive before it is applied is fast and inexpensive. But my deaeration ritual
is only based on the suspicion that it makes a difference. It would be nice to
know whether it should be part of everyone's technique toolbox or is a waste of
time. I suspect the answer may depend up the type of glue and materials
involved.
Mark Simpson
e-mail over the next few weeks. Being off from Dec.21-Jan.2 should give me lots
of time to think up some experiments.
Thanks for the offer,
Mark Simpson
NAR 71503 Level II
Alex Mericas
> First we need to decide weather or not this is worth everybody's time. Does
> anyone care? The second thing we need to decide on is what to test. I think
> the most versatile (and mostly debated) is various glues.
LOC style shock cord mounts vs eye-bolts vs ????
Elastic shock cord vs Kevlar
Masking tape thrust rings
Not sure how to word this, but some comparison of Fiberglass vs paper vs phenolic
(i.e. when should I use each)
For someone who likes to build rockets AT spec instead of OVER spec (i.e. with
a sufficient margin of error for likely stresses, but no more) I would be very
interested in some scientific studies to guide me in selecting the appropriate
material and method for the application at hand.
And while your at it, can you shed some light on the 3000 mile vs 5000 mile
oil change debate ;-)
--
Alex "I can divide by 5000 easier than 3000" Mericas
NAR 62956 Level 2
Senior Advisor, Austin Area Rocketry Group
tom savoie
tubular nylon in various knots
tubular nylon in various sewn
loops
snap links
forged eyebolts
All Thread
Tom Savoie
"Drake" <mo...@sprynet.com> wrote in message
news:9vcrtk$arn$1...@nntp9.atl.mindspring.net...
Drake
The bonding strength of various epoxies: JB-Weld, West Systems, ZPoxy, etc
and its strength of the bond to aluminum, QT, phenolic etc.
Evaluation of adhesive aeration (Could be interesting)
Strength of the building materials themselves:
Fiberglass
Kraft paper
Phenolic
Tubular nylon
Elastic shock cord
Kevlar
Shock cord various knots and sewn loops
Snap links
LOC style shock cord mounts
Forged and standard eyebolts
All Thread
I have recieved several e-mails. I also have a few people that have offered
to help by making test specimens. The more people participate the better and
more accurate the data. So far, testing of shock cord is definatly going to
happen. I have a few people sending me samples to test and I have some of my
own. I only need one foot sections.
If a glue test is chosen, we will first need decide on a method, then make
specimens. In any event, I will test all the samples I can come up with but
I can't do this with out other specimens to test.
Drake "Doc" Damerau
shrox
Shrox
-----------------------------------------
Tom Brekke
My opinion is that you need to pick one thing first and do all the testing
and not let this get so broad scoped that no one can get their arms around
it. I like the idea of testing adhesives but it needs to be more specific
then that so I'd further reduce that to just it's bonding capability to the
material or it's own strength ratio. To do that you'll need to select and
use the exact same materials to bond since bonding is also a function of the
material's ability to absorb. And if your doing epoxy, howbout adding Great
Plaines epoxy....to the list.. That is all I ever use. I haven't figured
out why everyone buys the expensive stuff they have to have shipped when you
can go to the hobby shop and get this stuff.
Tom
--
Remove "NOSPAM" before Replying.
"Drake" <mo...@sprynet.com> wrote in message
news:9vcrtk$arn$1...@nntp9.atl.mindspring.net...
Bobby B
Great Idea.......I suggest testing Gorilla glue on G10 and on PML tube.....
[ my favorite combination at present.......] I'd also like to test low cost
epoxy applications.......Loctite 5 min and 90 min to be more specific......
I also volunteer to host and maintain the project website if need be...... I
can make it interactive for discussions in addition to posting the test
data......Please advise if you would like me to set it up......
--
Bobby B
NAR 79350 L1
"Drake" <mo...@sprynet.com> wrote in message
news:9vcrtk$arn$1...@nntp9.atl.mindspring.net...
Bobby B
Great Idea.... I suggest testing gorilla glue on PML BT.. and Loctite 5 min
and 90 min epoxy with pml tube......
I also volunteer to set up and host a project website complete with a
discussion page.......if you need one....
http://www.pmcserv.com/hanger11/ youpickthename will be the URL.
--
Bobby B
NAR 79350 L1
"Drake" <mo...@sprynet.com> wrote in message
news:9vcrtk$arn$1...@nntp9.atl.mindspring.net...
Bob Kaplow
I don't know how many folks besides George Gassaway might be familiar with
Soartech, specifically #8 and the massive airfoil research Selig et al did.
They had access to a low speed wind tunnel. They got modellers across the
country to build models of all sorts of airfoils that Selig et al then
measured and tested.
The idea here is for us modellers to build test sections of whatever, ship
them to you for testing, then have the data made available to everyone. We'd
have to coordinate volunteers so 5 people don't do the same thing, but it
wouldn't hurt to have some duplication to see what effect modeller skill
plays in the results.
Bob Kaplow NAR # 18L TRA # "Ctrl-Alt-Del"
Kaplow Klips & Baffle: http://www.nira.chicago.il.us/Leading_Edge/MayJun00.pdf
NIRA: http://www.nira.chicago.il.us NAR: http://www.nar.org
The problem with governments is that citizens need to keep
them on a short leash; unfortunately the nature of the beast
is such that governments can usually arrange it so that only
they hold their own leash.
26-October, 2001: A day that will live in infamy
Support Freedom: http://www.indefenseoffreedom.org/
Jerry Irvine
> news:9vcrtk$arn$1...@nntp9.atl.mindspring.net...
> > First I'd like to thank everyone here. RMR and the HPR "community" as a
> > whole are a great bunch of people. I have been a lurker for some time now
> > and have been only just recently been asking a few questions. Many of you
> > have been helping me for a while and don't know it. I want to repay you
> > guys.
> >
> > Who am I? My friends call me Doc. I am the Chief Metallurgist and
> Laboratory
> > Director at The Scranton Army Ammunition Plant. And thus, this is how I
> can
> > repay the HPR community.
> >
Tube crush strength (end to end) for common tubes.
Quantum and phenolic and fiberglass at different temps.
Jerry
--
Jerry Irvine, Box 1242, Claremont, California USA
Opinion, the whole thing. <mail to:01ro...@gte.net>
Bring common sense back to rocketry administration.
Joel Corwith
and where he was planning on going:
http://www.jcsw.com/John/Rocketry/research.html
2 links at the bottom of the page. I'm interested in attachment points and
the strengths between the attached items and the attachment method. Does
the extra weight of a particular glue provide a benefit, or will what you're
gluing break first anyway. How does the strength of a knot (and different
knots) to attach tubular nylon differ from a sewn loop, and which is
sufficient following the ejection.
The list you posted is a great start.
Joel. phx
I imagine if you can kill the wood glue versus epoxy threads in the future,
people would be willing to chip in a few bucks ;)
Drake <mo...@sprynet.com> wrote in message
news:9vcrtk$arn$1...@nntp9.atl.mindspring.net...
Jerry Irvine
<rep...@thegroup.pls> wrote:
> I imagine if you can kill the wood glue versus epoxy threads in the future,
> people would be willing to chip in a few bucks ;)
>
Starting with me.
Alan Jones
>What I propose is this:
>Come up with a HPR strength of materials test. It could be tensile strength
>of shock cords, the compression strength of various airframes, tensile
>strength of glued substrates or something. We could glue pieces of Bud Nosen
>wood together or various shock cords or anything (within reason) else.
>The results can include, tensile strength, yield strength (at any strain),
>modulus, shear strength, compressive strength, fracture toughness, fatigue
>crack growth or any mechanical property you can think of. I can also then
>report the hardness (Rockwell) of the glue and the mode of failure
>(brittle/ductile).
>
>OK, Let the comments, suggestions, and flames fly.
>
>Drake "Doc" Damerau
I'd still like to see basic cmponent strenght of common body tubes,
particularly the three ply Estes tubes. I'd like to know the
longiitudinal bending strength and stiffness. and the longitudinal
compressive strength.
Alan Jones
Mr. Bill . . . Kennedy
I can help you with the oil change interval. Find a 'bulk-oil' distributer
in your town and ask for a 'sample kit'. It will have the containers and
mailer you'll need. Ours is from a Mobil oil dealer and are prepaid.
At @3000 miles, pull your sample and send it off. Ask for the simple
'viscosity breakdown' test which will include moisture and a few other
tests. It should run you no more than $15-$25.
Then you will see for yourself that the oil is fine at 3K and will perform
as required until 5K.
Now, it could go over 5K, but more complex things happen and you'd need to
get the complete 'particle' test to get a picture on whats happening to your
engine internally. Again cost should be $35-$50.
I may be off on a few details as I don't handle the paperwork anymore, just
pulling of the samples.
FWIW, I change mine at 5K, and always . . . always change the filter.
Later,
Mr. Bill
remove silly to send to Billy
"Alex Mericas" <alex-m...@austin.rr.com> wrote in message
news:3C1A422D...@austin.rr.com...
Mr. Bill . . . Kennedy
bonds and I can make some moola here.
I too am interested in building the samples for a specified size/material.
Question,
Do we limit or resources to 'market materials' or do we go for some
'professional adhesives' also. (I wouldn't want to waste Drakes time, unless
we're looking for standards)
Drake, I'd be interested in the sheer strength of the closure threads on a
reloadable casing.
Later,
Mr. Bill
Remove silly to reach Billy
"Joel Corwith" <rep...@thegroup.pls> wrote in message
news:syBS7.3035$cd.5...@news.uswest.net...
Drake
I can do shock cord at a rate of about 20 an hour each so I can pump those
out on a Saturday morning no problem. The machine is already programmed to
do this type of test and I even have all the fixtures. These will be easy.
The harder part is the glue testing. When we come up with the test, I'll
design the sample and have fixtures made.
Drake "Doc" Damerau
"Tom Brekke" <d-vike"NOSPAM"@prodigy.net> wrote in message
news:0AxS7.14826$Ao7.145...@newssvr16.news.prodigy.com...
Drake
cycle them overnight from temp to temp. Another quick and easy test. The
problem is cost. A 3" section of any tube will have more compressive
strength than a full size piece due to deflection. How many people do you
think will send me full airframe tubes?
Drake
"Jerry Irvine" <01ro...@gte.net> wrote in message
news:01rocket-141...@1cust225.tnt2.rancho-cucamonga.ca.da.uu.net..
.
Drake
I think we could handle it. The graphs (as you have seen) can be large but I
think everyone will want to see them. The data is plugged into a MS Word
table. Well post them too. I will then write a "discussion of data" No
opinions, just a summation of data. I will let everyone decide from there.
It looks like glue is becoming the favorite. You can do gorilla glue.
Drake "Doc" Damerau
"Bobby B" <bob...@frontiernet.net> wrote in message
news:u1lchi...@corp.supernews.com...
Drake
same sample as well as several different samples. This way we can look for a
variation of the same situation from builder to builder. Hopefully less than
3 sigma.
Drake "Doc" Damerau
"Bob Kaplow" <kapl...@eisner.encompasserve.org.mars> wrote in message
news:VOgO4s...@eisner.encompasserve.org...
Drake
some high-tech stuff. Who knows? We may find a better mouse trap.
I don't know if I have the heart to destroy a reloadable casing to find the
shear strength of the threads. They work so do we need to know how *well*
they work?
Drake "Doc" Damerau
"Mr. Bill . . . Kennedy" <sillybil...@worldnet.att.net> wrote in
message news:osCS7.296188$W8.10...@bgtnsc04-news.ops.worldnet.att.net...
Drake
for glue.
Drake "Doc" Damerau
"Alan Jones" <ala...@nospam.home.com> wrote in message
news:3c1cc5e9...@news.iowact1.ia.home.com...
Bobby B
I have been doing the 5000 mile change on 5 cars over 15 years of
driving.... mechanical engine problems have been ZERO....... I drive most to
150,000 mi or so before moving on. Current ride is a 1993 Eagle Vision Tsi
3.5L 6 cyl 125,000 mi.
ZERO problems.....
With respect to changing the filter every time.... real simple... never run
dirty oil thru a new filter.....
Change the filter with the oil.....
--
Bobby B
NAR 79350 L1
"Alex Mericas" <alex-m...@austin.rr.com> wrote in message
news:3C1A422D...@austin.rr.com...
Drake
I think the consensus is:
"The Bond Strength of Various Adhesives to Common HPR Materials"
How does this sound? Glue two flat pieces of the same thickness (rules out
fillets) together with any adhesive you wish. They can be like or dissimilar
materials. The only problem I see is with pieces of body tube. The curvature
will cause me grief in fixturing. Anybody have any thoughts here? Flat QT
material or flat Phenolic? Perhaps PML can help us here?
What we need to do is come up with a specimen geometry. The best for me
would be (2 pieces) of 2" x 6" x any thickness. Glue them end to end.
Remember: we are testing the bond strength, not fillets or the materials. I
think each person should do three samples of the same specimen. Of course
you are welcome to do as many as you wish, and of as many different
configurations you can come up with.
Each specimen should have your name on it and on a separate piece of paper,
include the following:
1.) Type of adhesive: CY, epoxy, aliphatic, bubble gum, white glue etc
2.) Working time for epoxies: Slow cure, 5 min., 30 min. ect
3.) Brand name of adhesive: West Systems, JB weld, Bob Smith, Bazooka Joe
etc.
4.) Type of substrate: 5 ply Aircraft plywood, G10, Kraft paper, phenolic,
your fingers etc.
5.) Brand mane of substrate: Bud Nosen, LOC, PML etc.
6.) I will record all of the dimensions
7.) Any other data you feel is pertinent: "sanded with 80 grit" or "cleaned
with alcohol" or "Vacuumed out bubbles" or whatever.
(Can anyone think of anything else?)
As the data is generated the results will be posted to the web site with
credit for the people who have contributed.
I will also do "Tensile Testing of Common HPR Shock Cords" Just because its
so easy to do. Can you spare a 1 foot section or two?
When we get ready to ship samples to me, the address is:
Drake Damerau
Chamberlain / Scranton Army Ammunition Plant
156 Cedar Ave.
Scranton, PA 18505
I will repost this address from time to time.
Drake "Doc" Damerau
Bob Kaplow
> Lets see how many people want to participate. If we have enough, we can add
> some high-tech stuff. Who knows? We may find a better mouse trap.
>
> I don't know if I have the heart to destroy a reloadable casing to find the
> shear strength of the threads. They work so do we need to know how *well*
> they work?
Maybe the manufacturers of the product would donate some? Ditto for the full
length tubes. I'd start with LOC and the pair of PML tubes. And no reason to
leave out ModRoc stuff. We need the same answers there, and much modroc
stuff ends up used in HPR.
Bob Kaplow NAR # 18L TRA # "Ctrl-Alt-Del"
Kaplow Klips & Baffle: http://www.nira.chicago.il.us/Leading_Edge/MayJun00.pdf
NIRA: http://www.nira.chicago.il.us NAR: http://www.nar.org
We need to ensure that actions by our government uphold the
principles of a democratic society, accountable government and
international law, and that all decisions are taken in a manner
consistent with the Constitution.
Bob Kaplow
> How does this sound? Glue two flat pieces of the same thickness (rules out
> fillets) together with any adhesive you wish. They can be like or dissimilar
> materials. The only problem I see is with pieces of body tube. The curvature
> will cause me grief in fixturing. Anybody have any thoughts here? Flat QT
> material or flat Phenolic? Perhaps PML can help us here?
Not being familiar with your aparatus, I think it's CRITICAL that we test
REAL body tube, and not some simulation. That means adapting to be able to
test round samples. And since fillets are part of our typical joint, they
should be included.
Drake
they want to prove that their stuff is as good as they say it is? Perhaps
they are a bit worried? I'm sure they will contact me in a few days. We need
to get the word out that we are doing this test.
Drake "Doc" Damerau
"Bob Kaplow" <kapl...@eisner.encompasserve.org.mars> wrote in message
news:AxXOsh...@eisner.encompasserve.org...
Drake
"Bob Kaplow" <kapl...@eisner.encompasserve.org.mars> wrote in message
> In article <9vff4m$8gd$1...@slb5.atl.mindspring.net>, "Drake"
<mo...@sprynet.com> writes:
> > How does this sound? Glue two flat pieces of the same thickness (rules
out
> > fillets) together with any adhesive you wish. They can be like or
dissimilar
> > materials. The only problem I see is with pieces of body tube. The
curvature
> > will cause me grief in fixturing. Anybody have any thoughts here? Flat
QT
> > material or flat Phenolic? Perhaps PML can help us here?
>
> Not being familiar with your aparatus,
Here is a link to my machine in my lab http://www.cmcscr.org/metallurgy.htm
This is a link to the manufacturers online brochure
Careful it's a *big* 3.8 MB pdf file
http://www.mts.com/materials/pdf/MatlTstgSolutions.pdf
>I think it's CRITICAL that we test
> REAL body tube, and not some simulation. That means adapting to be able to
> test round samples.
I agree but it may prove somewhat difficult to get accurate results. I will
see what I can come up with for fixturing.
>And since fillets are part of our typical joint, they
> should be included.
I think there will be too much variation. Your fillets my be thicker than
mine. We know that fillets strengthen the joint. If we just test the mating
surfaces then we can extrapolate the added "bonus" of adding fillets.
Jerry Irvine
<mo...@sprynet.com> wrote:
> I like this Idea too, especially the temperature variation part. I can even
> cycle them overnight from temp to temp. Another quick and easy test. The
> problem is cost. A 3" section of any tube will have more compressive
> strength than a full size piece due to deflection. How many people do you
> think will send me full airframe tubes?
I have a truclkoad. Where do you want them shipped to?
Jerry
Jerry Irvine
Jerry Irvine
<mo...@sprynet.com> wrote:
> >I think it's CRITICAL that we test
> > REAL body tube, and not some simulation. That means adapting to be able to
> > test round samples.
>
> I agree but it may prove somewhat difficult to get accurate results. I will
> see what I can come up with for fixturing.
>
> >And since fillets are part of our typical joint, they
> > should be included.
>
> I think there will be too much variation. Your fillets my be thicker than
> mine. We know that fillets strengthen the joint. If we just test the mating
> surfaces then we can extrapolate the added "bonus" of adding fillets.
>
Just terst them "as made" and document what "as made" is. The variance
from sample to sample will be telling indeed.
Jerry
Jerry Irvine
> Lets see how many people want to participate. If we have enough, we can add
> some high-tech stuff. Who knows? We may find a better mouse trap.
>
> I don't know if I have the heart to destroy a reloadable casing to find the
> shear strength of the threads. They work so do we need to know how *well*
> they work?
I am also willing to donate alot of those if alot of positive public
credit is given :)
Drake
don't see why a big "Thanks to company X or person" couldn't be on the main
web page. Even a banner. It will of course be made known why, and that there
is "no endorsement" ect.
Drake Damerau
Chamberlain / Scranton Army Ammunition Plant
156 Cedar Ave.
Scranton, PA 18505
"Jerry Irvine" <01ro...@gte.net> wrote in message
news:01rocket-151...@1cust51.tnt1.rancho-cucamonga.ca.da.uu.net...
Drake
see why a big "Thanks to company X or person" couldn't be on the main web
page. Even a banner. It will of course be made known why, and that there is
"no endorsement" ect.
Drake Damerau
Chamberlain / Scranton Army Ammunition Plant
156 Cedar Ave.
Scranton, PA 18505
"Jerry Irvine" <01ro...@gte.net> wrote in message
news:01rocket-151...@1cust51.tnt1.rancho-cucamonga.ca.da.uu.net...
Drake
Drake"Doc" Damerau
"Jerry Irvine" <01ro...@gte.net> wrote in message
news:01rocket-151...@1cust51.tnt1.rancho-cucamonga.ca.da.uu.net...
Mark Simpson
ever-difficult butt joint. I'll help prepare some samples for that test. >;-)
Mark Simpson
NAR 71503 Level II
Unknown
of any given airframe can be computed using column buckling formulae
from any engineering handbook.
Aren't the properties for most of these materials available, either
from handbooks, textbooks, or manufacturers?
Unknown
testing materials so the results are consistent and can be compared
with one another.
Drake
have written many testing procedures and standards. All of the testing I do
is in accordance to any, and all applicable ASTM or MIL standards.
FWIW, I am also a member of ASM and SAE.
Our proposed testing will be in good hands.
--
Drake "Doc" Damerau
.
<Kevin Reed> wrote in message news:3c1e7747...@news.mindspring.com...
Drake
buckling formulas. I thought it would be better to show actual test results
on real lengths.
I'm sure the nominal properties for nominal materials are available but
again, vendor to vendor may make a difference.
The original idea I had was to test various glues to various materials and
find the best combinations.
--
Drake "Doc" Damerau
.
<Kevin Reed> wrote in message news:3c1e7625...@news.mindspring.com...
Alan Jones
>Once the material properties are established, the maximum axial load
>of any given airframe can be computed using column buckling formulae
>from any engineering handbook.
It is not that easy. Column buckling depends mostly on the bending
stiffness, and resulting stability, rather than the bending strength,
or asial compression strength. Airframes are not typicaly loaded
axialy like structural columns. But yes, with a complete set of
material properties, you can apply structural engineering methods.
>Aren't the properties for most of these materials available, either
>from handbooks, textbooks, or manufacturers?
I have not seen any for the common three ply spiral wound Estes tubes.
Thicker multi-ply tubes are easier to guestimate. I think the seams
plays a dominant role in the structural properties of Estes Three ply
tubes. Also in bending, the thin walled tube will tend to flatten as
it bends. Sometimes you get minute localised crusshing of only the
seam, and sometimes you get complete crippling at the seam. We need a
complete set of structural test data for these tube,, complete with
detailed ofservations. Then we can develop dependable engineering
models for the tubes and apply engineering analysis.
>"Drake" <mo...@sprynet.com> wrote:
Alan Jones
kallend
Alan Jones wrote:
>
We need a
> complete set of structural test data for these tube,, complete with
> detailed ofservations. Then we can develop dependable engineering
> models for the tubes and apply engineering analysis.
>
>
> Alan Jones
I don't think we "need" any such thing. Would be kind of nice to have,
though.
jk
koko
> stiffness, and resulting stability, rather than the bending strength,
> or asial compression strength. Airframes are not typicaly loaded
> axialy like structural columns.
????? !!!!!
These threads sure are long, but not too many responses from actual
structural engineers. Are there some, or do they just not want to
respond???
:-)
Jerry Irvine
I spent a good part of today preparing an initial care package for these
tests. Generally it includes 3" tubes, 2.6" tubes, 2.25" tubes, couplers
to match, 1.22" tubes, 1" tubes, lite ply and aircraft ply fins, rings,
shock cords, and possibly some misc stuff I forgot.
It is a start.
Drake
structural engineer. My forte is metallurgical failure analysis. My strength
of materials background does apply to structural engineering as applied to
load/stress but I couldn't design a structure very well. (I would probably
make a shopping cart out of an alpha titanium alloy)
--
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Drake "Doc" Damerau
.
"koko" <koko...@att.net> wrote in message
news:4bWT7.231465$3d2.11...@bgtnsc06-news.ops.worldnet.att.net...
Drake
Thanks Jerry.
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Drake "Doc" Damerau
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"Jerry Irvine" <01ro...@gte.net> wrote in message
news:01rocket-181...@1cust210.tnt1.rancho-cucamonga.ca.da.uu.net..
.
Joel Corwith
ShOOOrt!!!! I just read that!!! Tooo funny!
> Drake "Doc" Damerau
Joel. phx
David Weinshenker
> (I would probably make a shopping cart out of an alpha titanium alloy)
And would that be a good or a bad sort of
titanium alloy to make a shopping cart out of?
-dave w
Andy Eng
My guess it would probably be nice and light (easier to push around)
and good for speeds above mach... :-)
Regards,
Andy
Alan Jones
I don;'t think there are Structual Engineers. There are various
degreed engineers who work in the structures field. I'm Aero.
E./Controls. I did ace all my structures courses, but I found
structures too dull, cut and dried, Ands I have had some experience
determining structural loads for missiles. But yes, I'd welcome "an
actual structural engineer" who chimed in and stated the case more
elegantly.
Alan Jones
Drake
Very very light. High strength/weight ratio. High impact toughness, excelent
cold service, very corosion resistant. You could fill that puppy to the top
with all the heavy stuff like beer, spare ribs,and car bateries. You know, a
trip to Wall Mart.
--
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Drake "Doc" Damerau
.
"Andy Eng" <ae...@ghg.net> wrote in message
news:3c2101b6...@news.cis.dfn.de...
koko
> >> stiffness, and resulting stability, rather than the bending strength,
> >> or asial compression strength. Airframes are not typicaly loaded
> >> axialy like structural columns.
> >
> degreed engineers who work in the structures field.
> actual structural engineer" who chimed in and stated the case more
> elegantly.
Well, I've been a structural engineer for almost 24 years. (But then I
started building rockets about 38 years ago.) So I guess I'll have to say
something.
As far as the original subject goes...
The primary strength mode of an airframe is probably buckling under
compression loads, and would be similar to compression loads on structural
columns. A secondary form of load is probably a bending mode from vibration
and/or aerodynamic buffeting.
Under mostly axial loads, the behavior of the tube depends on its
cross-section area and its bending/buckling stiffness. The bending/buckling
stiffness depends on the stiffness of the material itself and on the
configuration (diameter and wall thickness). There is probably some
difference in material stiffness between manufacturers and this could be
tested. However except for real long rockets pure elastic buckling is not
the failure mode, in other words the strength of the materials becomes a
limiting factor. Now we're getting to a point, the strength of the
materials, that can be tested and may vary quite a bit from one manufacturer
to another.
I would recommend testing a normal length of tube, such as 34 inches, and of
a medium diameter such that it doesn't immediately buckle like a soda-straw
would. Of course a 6" long piece of fat tubing wouldn't buckle in this
manner at all whereas there may be some tendency of a normal rocket airframe
to buckle so the 6" long tube isn't a representative test either. (The 6"
long tube would likely fail through local buckling. At this point the
applied loads are probably higher than what we are working with in rockets
except during lawn-dart maneuvers.) The first round of tests might just
take several different tube diameters of the same length and test all of
them to see what the failure mode was, then pick the length to diameter that
best approximated failure of an actual airframe, then use that for all
future tests.
Lew Garrow
disallowing the use of engines more vigorous than the D12 - discuss amongst
yourselves....
8-)
>Subject: Re: HPR Strength of Materials Study
>From: "koko" koko...@att.net
>Date: 12/20/2001 1:38 AM Eastern Standard Time
>Message-id: <MHfU7.233211$3d2.11...@bgtnsc06-news.ops.worldnet.att.net>
Lew Garrow
TRA 7181 L3
NAR 77928 L3
METRA BOD
Maryland Delaware Assn
Andy Eng
You mean such as like a prophylactic over one of your hybrids? :-)
I do have a question to Koko & Alan if they're still around and that's
that I've *some* blackshaft tubing left that I'd be willing to send in
but struggling with what would be useful lengths for testing. I've
some 24mm, 18mm, 13mm & 4mm(?) but only a few pieces of each.
Would samples 6" long be useful? I'd hate to have to destroy a 30"
piece in just one test.
TIA,
Andy
On 20 Dec 2001 15:19:20 GMT, lgarr...@aol.complex (Lew Garrow)
wrote:
Drake
shipping tube in the morning. I will post this preliminary data tomorrow
night on ABMR.
--
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Drake "Doc" Damerau
.
"koko" <koko...@att.net> wrote in message
news:MHfU7.233211$3d2.11...@bgtnsc06-news.ops.worldnet.att.net...
Drake
data will go up on the RMR HPR Strength of Materials Study pages.
--
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Drake "Doc" Damerau
.
"Andy Eng" <ae...@ghg.net> wrote in message
news:3c221eb8...@news.cis.dfn.de...
Drake
tested at ambient temperature.
I have the website up for the data. No flames. It's just up, and crude. I
will "fix it up" as I go along. You can access it from my home page at
http://home.sprynet.com/~monel/
Again, all samples can be sent to:
Drake Damerau
Chamberlain/
Scranton Army Ammunition Plant
Scranton, PA 18505
Jerry Irvine
<mo...@sprynet.myshorts.com> wrote:
> I am testing all tube sent.
Be careful what you promise, I'll send more.
Alan Jones
>I do have a question to Koko & Alan if they're still around and that's
>that I've *some* blackshaft tubing left that I'd be willing to send in
>but struggling with what would be useful lengths for testing. I've
>some 24mm, 18mm, 13mm & 4mm(?) but only a few pieces of each.
>
>Would samples 6" long be useful? I'd hate to have to destroy a 30"
>piece in just one test.
>
>TIA,
>Andy
The only think I use Blackshaft for is piston tubes, and that is with
a light wrap of fiberglass. I'd send in the maximum lenghts
avajilable and let Drake cut them to appropriate lenghts for his
laoding fixtures and testing program. He mentioned that he had an 18"
three point loading fixture for bending loads, but I'd rather use a
four point loading fixture to put the specimin in pure bending.
Someone else suggested testing three different lengths for the axial
loading tests. That may translate into testing three different L/D
ratio specimins for each different tube type.
I'm mostly interested in the three ply Estes tubes. I'd send some in,
buut does not make much sence for a bunch of people to go to all the
bother and expense to ship an item that is probably available jin the
local hobby shop. I'd rather send send in a cash donation. Or
perhaps I should send you some money and let you do the packing and
shipping? Then again, a lot of these grand plans just fall apart when
they get down to the details of just doing it.
Alan Jones
Alan Jones
>As far as the original subject goes...
>The primary strength mode of an airframe is probably buckling under
>compression loads, and would be similar to compression loads on structural
>columns.
I was going to dissagree here, but...
>At this point the
>applied loads are probably higher than what we are working with in rockets
>except during lawn-dart maneuvers.)
I concede that lawn-darts provide very high axial loading of the
airframe and may result in Euler column buckling. However, I don't
like designing, building, or flying crashworthy designs. I'm more
concerned avout the in flight loads, and corresponding structural
properties.
Alan Jones
Alan Jones
wrote:
>OK here is your topic for discussion - the DUDE's structural weaknesses
>disallowing the use of engines more vigorous than the D12 - discuss amongst
>yourselves....
>8-)
>Lew Garrow
You could probably derive a usefull relationship beween the fliight
dynamic pressure encountered and the internal inflation pressure
required. Then follow it up with some testing. So I guess the blow
hards have a competitive advantage here.
Alan Jones
Drake
seen a four point fixture. (I'm not saying they don't exist) ASTM and the US
Army feels that the 3 point fixture is pure bending.
I did not plan to use it for tube testing. I planed on using it for fin and
bulkhead materials. I planed on testing the tubes by crushing them, end for
end, between two platens at a preset rate and measuring the stress/strain.
Each tube will be measured and the data will be studied. The L/D ratio will
be included as a group for each material tested.
I promise that this study will not fall apart.
The (as yet completed) webpage for the data will be at:
http://home.sprynet.com/~monel/rmr.htm
--
Remove "my shorts" to e-mail me.
Drake "Doc" Damerau
.
"Alan Jones" <ala...@nospam.home.com> wrote in message
news:3c269ab9...@news.iowact1.ia.home.com...
Leonard Fehskens
news:3c249733...@news.iowact1.ia.home.com:
> I concede that lawn-darts provide very high axial loading of the
> airframe and may result in Euler column buckling.
But that's what nose cones are for!
len.
Drake
I tested two tubes today. They were PML 3" phenolic. The data is up on the
RMR Test page. You can get to it via my website at:
http://home.sprynet.com/~monel/home.htm
Just follow the obvious links.
I would have tested more but that's all I had left in my box of goodies.
(Nothing anyone has sent me has come in yet) I was, to say the least,
shocked at the outcome. The nominal peak load before catastrophic overload
failure was about 3200 lbs of force. There was a significant difference
between the 6" length to the 10" piece. I cant explain this other than we
are looking at a statistical population of two.
I have reams of data so if you want to see something that's not there I can
add it.
I will keep posting data as I generate it.
Happy Holidays to all.
Andrew Knox
(thought it was Rolls Over Laughing until the context didn't fit).
Regards
Andrew S Knox (andrew...@btinternet.com)
"Drake" <mo...@sprynet.myshorts.com> wrote in message
news:9vu3oj$h8h$1...@slb7.atl.mindspring.net...
Andrew Knox
apology)
Has anybody been using strain gauges (along with accelerometers and pressure
sensors I suppose) with recording or telemetry, to find out what happens
during flight?
Regards
Andrew S Knox (andrew...@btinternet.com)
"Alan Jones" <ala...@nospam.home.com> wrote in message
news:3c249733...@news.iowact1.ia.home.com...
Unknown
"Drake" <mo...@sprynet.com> wrote:
>Yes. I am a member of ASTM and I'm on the materials testing committee. I
>have written many testing procedures and standards. All of the testing I do
>is in accordance to any, and all applicable ASTM or MIL standards.
>
>FWIW, I am also a member of ASM and SAE.
>Our proposed testing will be in good hands.
>
>--
>Drake "Doc" Damerau
>
>.
><Kevin Reed> wrote in message news:3c1e7747...@news.mindspring.com...
>> Do you have access to ASTM? They publish standards and procedures for
>> testing materials so the results are consistent and can be compared
>> with one another.
>>
>>
>> "Drake" <mo...@sprynet.com> wrote:
>>
>> >I can do it if the consensus decides on it. But it looks like we are
>going
>> >for glue.
>> >
>> >Drake "Doc" Damerau
>> >
>> >"Alan Jones" <ala...@nospam.home.com> wrote in message
>> >news:3c1cc5e9...@news.iowact1.ia.home.com...
>> >> On Fri, 14 Dec 2001 07:40:01 -0500, "Drake" <mo...@sprynet.com> wrote:
>> >>
>> >>
>> >> >What I propose is this:
>> >> >Come up with a HPR strength of materials test. It could be tensile
>> >strength
>> >> >of shock cords, the compression strength of various airframes, tensile
>> >> >strength of glued substrates or something. We could glue pieces of Bud
>> >Nosen
>> >> >wood together or various shock cords or anything (within reason) else.
>> >>
>> >> >The results can include, tensile strength, yield strength (at any
>> >strain),
>> >> >modulus, shear strength, compressive strength, fracture toughness,
>> >fatigue
>> >> >crack growth or any mechanical property you can think of. I can also
>then
>> >> >report the hardness (Rockwell) of the glue and the mode of failure
>> >> >(brittle/ductile).
>> >> >
>> >> >OK, Let the comments, suggestions, and flames fly.
>> >> >
>> >> >Drake "Doc" Damerau
>> >>
>> >> I'd still like to see basic cmponent strenght of common body tubes,
>> >> particularly the three ply Estes tubes. I'd like to know the
>> >> longiitudinal bending strength and stiffness. and the longitudinal
>> >> compressive strength.
>> >>
>> >> Alan Jones
>> >>
>> >
>> >
>>
>
>
Drake
http://home.sprynet.com/~monel/
I received a box from Jerry Irvine yesterday. (This is the only thing I have
received so far) Shipping/receiving brought it to me via a forklift! OK,
they probably could have brought it on a dolly but they are kind of lazy. I
didn't count them, but there _had_ to be at least 100 tubes in there. He
sent his USR "Whitewall" tubes and glassine tubes from 24mm to 3" in several
lengths. He also sent some fins and centering rings. Kudos to Jerry!
I was busy yesterday but I managed to test 6 of his 3" white wall tubes
tubes. I'm putting the data from these tubes up on the site now and I'm
going in to test more in a few hours. I will post the results from today's
testing when I get home.
I will make a prototype fin can with some of his stuff. When I complete it,
I will make several kits just like it. E-mail me if you would like to build
one of these kits and send it back to me. I don't know yet how many I will
be able to make.
--
Remove "my shorts" to e-mail me.
Drake "Doc" Damerau
.
"Andrew Knox" <andrew...@btinternet.com> wrote in message
news:cw3X7.60070$4z5.8...@news6-win.server.ntlworld.com...
Drake
--
Remove "my shorts" to e-mail me.
Drake "Doc" Damerau
.
<Kevin Reed> wrote in message news:3c2cf18d...@news.mindspring.com...
Jack Wiker
Jerry Irvine
<mo...@sprynet.myshorts.com> wrote:
> The data is on my we site at :
> http://home.sprynet.com/~monel/
>
> I received a box from Jerry Irvine yesterday. (This is the only thing I have
> received so far) Shipping/receiving brought it to me via a forklift! OK,
Is there any other way to travel?
> lengths. He also sent some fins and centering rings. Kudos to Jerry!
Lets discuss how to test these. I invisioned them glued into a sample tube
and pressed out (we recommend Titebond II or 30 minute epoxy), so either
of these are my first choice. The fins should be surface attached and
through wall attached to test that feature, again Titebond default.
I also sent couplers so you can measure deflection between coupled tubes.
The motor mount tubes once crushed will show maximum thrust they can
handle. It will then be the mission of the average reader to try to max
it out in practice with USR motors and publish the result.
>
> I was busy yesterday but I managed to test 6 of his 3" white wall tubes
> tubes. I'm putting the data from these tubes up on the site now and I'm
> going in to test more in a few hours. I will post the results from today's
> testing when I get home.
>
> I will make a prototype fin can with some of his stuff. When I complete it,
> I will make several kits just like it. E-mail me if you would like to build
> one of these kits and send it back to me. I don't know yet how many I will
> be able to make.
>
Supporting the rocket industry advancements since 1972
Jerry Irvine
Drake
Mechanical Testing
Here is a link:
http://www.astm.org/cgi-bin/SoftCart.exe/COMMIT/COMMITTEE/E28.htm?L+mystore+
utrt1114+1009645234
--
Remove "my shorts" to e-mail me.
Drake "Doc" Damerau
.
"Jack Wiker" <jac...@attbi.com> wrote in message
news:3C2DE3B7...@attbi.com...
> Which (number-letter) committee would that be?
>
> >>Yes. I am a member of ASTM and I'm on the materials testing committee. I
Jerry Irvine
<mo...@sprynet.myshorts.com> wrote:
http://www.astm.org/cgi-bin/SoftCart.exe/COMMIT/COMMITTEE/E28.htm?L+mystore+utrt1114+1009645234
--
Unknown
ASME is the American Siciety of Mechanical Engineering. www.asme.org.
Unknown
it seems to be the most common way to characterize adhesive strength.
For most design work, materials are usually specified in a range of
values for mechanical properties, and then MEs design conservatively
-- using lowest accepted values, adding a safety factor, that sort of
thing.
Testing comparable materials from all the different sources would give
a range of values for materials data.
BJamesjr
This message may be a little late, but I would recommend testing a full length
piece first. Depending on results of the test you could alter the testing
method.
If you test only a short section, the only behavior you will likely see is
local buckling, much like when you crush an aluminum drink can. When you test
the longer tube then you get the effects of flexure (euler buckling).
Drake
http://home.sprynet.com/~monel/home.htm
There is some data not up yet. (I left it at work) I'll post it tomorrow.
The results of the PML phenolic tube was surprising at first. The longer
tube had much higher results than the shorter tube. I did a failure analysis
and found out what happened. The gaps you see on the ID and OD are also in
the inside of the wall because the tube is built in layers. There are areas
randomly throughout the length of the tube where these interior gaps are
stacked and closer than normal. This is where the shorter tube broke. I know
this sounds somewhat vague but some of the things I found doing my failure
analysis should not be disclosed. It wouldn't be fair to PML.
I expect more tubes this week.
--
Remove "my shorts" to e-mail me.
Drake "Doc" Damerau
.
"BJamesjr" <bjam...@aol.com> wrote in message
news:20020101014820...@mb-fr.aol.com...
Drake
arguments has always been to use longer curing epoxy to allow it time to
soak into the materials. I am putting together a test for a HPR fin/glue
test now. Using some of the components Jerry sent me, I'm making some fin
can kits. When they are complete, I will post a request for people to
assemble them with various adhesives. They will consist of a body tube,
centering rings and fin material. The builder will be requested to assemble
them, fill out a data sheet and return them to me.
--
Remove "my shorts" to e-mail me.
Drake "Doc" Damerau
.
<Kevin Reed> wrote in message news:3c311b9...@news.mindspring.com...
Jerry Irvine
<mo...@sprynet.myshorts.com> wrote:
> Testing the glue itself may not relate to building rockets. One of the
> arguments has always been to use longer curing epoxy to allow it time to
> soak into the materials. I am putting together a test for a HPR fin/glue
> test now. Using some of the components Jerry sent me, I'm making some fin
> can kits. When they are complete, I will post a request for people to
> assemble them with various adhesives. They will consist of a body tube,
> centering rings and fin material. The builder will be requested to assemble
> them, fill out a data sheet and return them to me.
If you ask me to send more, I will. But pull up the fork lift.
Jerry
Alan Jones
<mo...@sprynet.myshorts.com> wrote:
> I know
>this sounds somewhat vague but some of the things I found doing my failure
>analysis should not be disclosed. It wouldn't be fair to PML.
That is complete BS, unless you are testing under contract to PML, or
have a gentlemans agreement to do private testing. However, you
solicited public coments and contributios, and claimed that results
would be made public.
Drake
the US Army and failure analysis for steel processors. I think you may be
misunderstanding the situation.
The 10" tubing broke with considerably more force than did the 6" sample. I
found this to be contradictory to "common sense". I did a failure analysis.
Part of that was contacting PML and they discussed the failure with me. The
only thing I did not disclose was PML's method of manufacturing the tube
itself. PML's manufacturing practices and process are not by business to
disclose.
EVERY bit of pertainant TESTING data has been disclosed and uploaded. I do
have reams of data that is not there only because of space limitations and
it does not apply to life as most people know it. Things like 4 different
modulus, yields at 10 stress offsets and other irrelevant data like absorbed
energy.
Frankly, I'm a little disappointed with PML. Being one of the larger
manufacturers, I thought they would jump in and help us out. The only
company to come forward is Jerry at USR. I have had absolutly zero help from
any company or website. The only people steping up is us rocketeers.
--
Drake "Doc" Damerau
Remove "my shorts" to e-mail me
HPR Strength of Materials Site:
http://home.sprynet.com/~monel/rmr.htm
"Alan Jones" <ala...@nospam.home.com> wrote in message
news:3c334de4...@news.iowact1.ia.home.com...
Drake
You or any one else here is welcome to come to watch/help.
--
Drake "Doc" Damerau
Remove "my shorts" to e-mail me
HPR Strength of Materials Site:
http://home.sprynet.com/~monel/rmr.htm
"Alan Jones" <ala...@nospam.home.com> wrote in message
news:3c334de4...@news.iowact1.ia.home.com...
BJamesjr
>found this to be contradictory to "common sense"
Sounds like you had some form of local failure, perhaps due to variations in
the strength of the tube depending on how the wraps/joints line up. Of course
this is useful information in and of itself, since a person interested in
strength might be able to hand-pick tubes with the right configuration. Also,
the manufacturer might be able to have some control over the manufacturing
process to eliminate this random difference in strength.
If you have additional materials you should repeat this particular test to see
if the results are consistent.
BJamesjr
>arguments has always been to use longer curing epoxy to allow it time to
>soak into the materials.
It always seemed to me that the strength of the tube was the limiting factor.
In other words if you glued something to the surface of the tube then pulled on
it until it came off, it would de-laminate the tube rather than failing the
glue.
I've decided that for some uses, I can substitute yellow glue for epoxy. It is
cheaper and easier to use. It doesn't build up fillets worth a darn though so
I still use epoxy for that.
Jerry Irvine
<mo...@sprynet.myshorts.com> wrote:
> I have no contracts with anybody and the only "private" testing I do is for
> the US Army and failure analysis for steel processors. I think you may be
> misunderstanding the situation.
>
> The 10" tubing broke with considerably more force than did the 6" sample. I
> found this to be contradictory to "common sense". I did a failure analysis.
> Part of that was contacting PML and they discussed the failure with me. The
> only thing I did not disclose was PML's method of manufacturing the tube
> itself. PML's manufacturing practices and process are not by business to
> disclose.
>
> EVERY bit of pertainant TESTING data has been disclosed and uploaded. I do
> have reams of data that is not there only because of space limitations and
> it does not apply to life as most people know it. Things like 4 different
> modulus, yields at 10 stress offsets and other irrelevant data like absorbed
> energy.
>
> Frankly, I'm a little disappointed with PML. Being one of the larger
> manufacturers, I thought they would jump in and help us out. The only
> company to come forward is Jerry at USR. I have had absolutly zero help from
> any company or website. The only people steping up is us rocketeers.
It is hard to coperate on this type of test. It is a diversion of company
resources so I would stand behind PMLs unwise decision.
I am set up to cooperate because I originally set the standards HPR now
follows. I have plenty of excess inventory to dispose of because I have
been doing it for so long. I appreciate the kind words, and will continue
to support the tests fully. But lets not rag on PML or LOC if they are
not as fast or full to cooperate. They also have a higher cost basis on
parts than I do, due to both purchase quantities and market size. HPR has
shrunk some 70% in the past 10 years. My market thank goodness has
remained fairly steady.
I am not serving the TRA and NAR marketplace simply because they have
indicated they do not want me to. If nothing else I do not choose to
fight an uphill battle. I will continue to say please, to cooperate, but
not beg or force or sue.
Jerry Irvine
(BJamesjr) wrote:
> >The 10" tubing broke with considerably more force than did the 6" sample. I
> >found this to be contradictory to "common sense"
>
> Sounds like you had some form of local failure, perhaps due to variations in
> the strength of the tube depending on how the wraps/joints line up. Of course
> this is useful information in and of itself, since a person interested in
> strength might be able to hand-pick tubes with the right configuration. Also,
> the manufacturer might be able to have some control over the manufacturing
> process to eliminate this random difference in strength.
Not likely at all with any spiral tube process.
>
> If you have additional materials you should repeat this particular test to see
> if the results are consistent.
--
Drake
--
Drake "Doc" Damerau
Remove "my shorts" to e-mail me
HPR Strength of Materials Site:
http://home.sprynet.com/~monel/rmr.htm
"BJamesjr" <bjam...@aol.com> wrote in message
news:20020102235751...@mb-mo.aol.com...
Drake
--
Drake "Doc" Damerau
Remove "my shorts" to e-mail me
HPR Strength of Materials Site:
http://home.sprynet.com/~monel/rmr.htm
"Jerry Irvine" <01ro...@gte.net> wrote in message
news:01rocket-020...@1cust129.tnt3.san-bernardino.ca.da.uu.net...
I don't blame PML or any one else. I mean, who the heck am I? They don't
know me from Adam, _or_ what my intentions are. I would be leary of jumping
in too. I guess I'm just saying I'm disapointed. I should have worded that
diferently. I was called outside my name and I was a little upset. I truly
appreaciate everything that people are sending me.
Drake
--
Drake "Doc" Damerau
Remove "my shorts" to e-mail me
HPR Strength of Materials Site:
http://home.sprynet.com/~monel/rmr.htm
"Jerry Irvine" <01ro...@gte.net> wrote in message
news:01rocket-020...@1cust129.tnt3.san-bernardino.ca.da.uu.net...
> In article <20020102235751...@mb-mo.aol.com>, bjam...@aol.com
> (BJamesjr) wrote:
>
> > >The 10" tubing broke with considerably more force than did the 6"
sample. I
> > >found this to be contradictory to "common sense"
> >
> > Sounds like you had some form of local failure, perhaps due to
variations in
> > the strength of the tube depending on how the wraps/joints line up. Of
course
> > this is useful information in and of itself, since a person interested
in
> > strength might be able to hand-pick tubes with the right configuration.
Also,
>
> > the manufacturer might be able to have some control over the
manufacturing
> > process to eliminate this random difference in strength.
>
> Not likely at all with any spiral tube process.
With phenolic tubing, measure the width of the ID wrap and the gaps, then
measure the width of the OD wrap and its gap, then think about how many
layers there are. Then run some laws of probibility equations and see what
happens. Do this on two diferent tubes.
I only had the two pieces of tubing to test. I hope to get more soon. We may
see a lower standard deviation. I _HATE_ stistical populations of two!