Ok, this may seem like a proposterous idea, but our client insist, and I was
told to come up with an educated response:
Here's the deal - out of our flexible membranes he intend to make some
inflatable articles (i assume dummies or scenery objects) to be placed in a
paint-ball guns playfround. He is asking will the membrane be damaged by the
pellets. He has given us details as per the pellets (weight, exit velocity),
and i have thorough knowledge of the membrane's mechanical properties, as we
are the manufacturer (calendering, over a standard PES high tenacity
textile). I can calculate the pellets momentum and energy, and can estimate
the pellets' cross-sectional area. However, I have not idea how to relate
this to what i can tell of the membrane (strip tensile strength, tear
strength, puncture resistance). I have no impact energy to break/tear the
membrane as it is flexible, izod is inappropriate. puncture is under nearly
static loading. tear is highly influenced by geometry (and rate of strain).
I can say from personal experience that such a pellet does not break the
skin of humans, nor does it penetrate the thin protective garment each
player is required to wear. I would just like to translate that into
quantitive form, as so not to appear "guestimating".
I also though it would make a fun and interesting thread topic, while still
in the realm of materials (I hesitated weather this should be posted on
sci.polymers instead...)

TIA

E.V

I would just like to translate that into
quantitive form, as so not to appear "guestimating".

Ok, this may seem like a proposterous idea, but our client insist, and I was
told to come up with an educated response:

Here's the deal - out of our flexible membranes he intend to make some
inflatable articles (i assume dummies or scenery objects) to be placed in a
paint-ball guns playfround. He is asking will the membrane be damaged by the
pellets. He has given us details as per the pellets (weight, exit velocity),
and i have thorough knowledge of the membrane's mechanical properties, as we
are the manufacturer (calendering, over a standard PES high tenacity
textile). I can calculate the pellets momentum and energy, and can estimate
the pellets' cross-sectional area. However, I have not idea how to relate
this to what i can tell of the membrane (strip tensile strength, tear
strength, puncture resistance). I have no impact energy to break/tear the
membrane as it is flexible, izod is inappropriate. puncture is under nearly
static loading. tear is highly influenced by geometry (and rate of strain).
I can say from personal experience that such a pellet does not break the
skin of humans, nor does it penetrate the thin protective garment each
player is required to wear. I would just like to translate that into
quantitive form, as so not to appear "guestimating".
I also though it would make a fun and interesting thread topic, while still
in the realm of materials (I hesitated weather this should be posted on
sci.polymers instead...)

Erez Volach wrote:
sci.polymers instead...)

If the impact force exceeds the elastic limit of the polymer membrane
it will inelastically deform (irreversibly stretch). This may
strengthen or weaken it, and may open up new failure modes as well as
degrade visual aesthetics.

KISS - make some prototypes (or visit the local toy store) and blast
away with the nastiest weaponry! What you see is the answer. Go back
and work the maths accordingly. Be sure to blast at the seams.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net!