I have searched for reference and handbook information (yes, google too)
describing the load behavior of randomly tangled wool-like fiber matte.
The
interest is to design a wool-like material for elastic constant and
stiffness depending on the materials properties, volume fraction and
geometry (fiber thickness, cross section, length) of the fibers involved.
Materials will be inorganic fibers and not polymers or natural fibers.
Fibers will likely be curled or twisted and not straight. That should not
constrain the governing equations. I have no idea what governing
equations
there may be. I expect there are empirical relations to use? There must
be
some engineering work from ancient subjects like pillow making, steel
wool,
filters or packaging. Fiber books don't cover this topic. No materials
books or chapters in them address such topics.
If there is a clue out there among you to resolve this, and you have read
this far, then let me add further refinements. Say I want to make a
fibrous
matte much like Fiberfrax or the like. How might the mechanical
compressibility change if a heat treatment allows fiber interconnects to
form (sintering). Adhesives or sintering can ultimately make the matte
into
a rigid structure. I wish to control stiffness or the spring constant but
maximize the compressed volume ratio. How would the properties change if
I
substituted sapphire fibers for silica glass for example?
A book, web site, name of subject area or good keyword is all I ask.

You have a fundamental problem, in that fibre mats themselves have no
intrinsic strength. They are all resilient and easily deformed. It is only
by mechanically bonding the fibres together that any web strength is
achieved. This may involve mechanical looping, as in needle mat, where
chopped strands are held in a veil support, or chemical bonding as
typified
by emulsion or powder-bound chopped strand mat, or typical insulation
fibre
blankets. Another approach is to make a paper-like material of dispersed
fibres.

You ask about the use of sapphire fibres. I presume that you have done a
Google search for "Saffil"?
--
Terry Harper
http://www.terry.harper.btinternet.co.uk/

I have searched for reference and handbook information (yes, google too)
describing the load behavior of randomly tangled wool-like fiber matte. The
interest is to design a wool-like material for elastic constant and
stiffness depending on the materials properties, volume fraction and
geometry (fiber thickness, cross section, length) of the fibers involved.
Materials will be inorganic fibers and not polymers or natural fibers.
Fibers will likely be curled or twisted and not straight. That should not
constrain the governing equations. I have no idea what governing equations
there may be. I expect there are empirical relations to use? There must be
some engineering work from ancient subjects like pillow making, steel wool,
filters or packaging. Fiber books don't cover this topic. No materials
books or chapters in them address such topics.
If there is a clue out there among you to resolve this, and you have read
this far, then let me add further refinements. Say I want to make a fibrous
matte much like Fiberfrax or the like. How might the mechanical
compressibility change if a heat treatment allows fiber interconnects to
form (sintering). Adhesives or sintering can ultimately make the matte into
a rigid structure. I wish to control stiffness or the spring constant but
maximize the compressed volume ratio. How would the properties change if I
substituted sapphire fibers for silica glass for example?
A book, web site, name of subject area or good keyword is all I ask.

Prof. K

One of my favorite "lectures" is how much we materials science guy jabbrer on about microstructure and material properties, and how little we actually know about it.

You understand the problem. Thank You.
Saffil is like Nextel which is one of my materials. I should revisit
Saffil
since the material might be engineered to a greater degree than their
commercial products. Thanks for activating that neuron that opened that
interconnect.
I wish to take advantage of the resiliency and predictably increase the
strength until the resiliency is reduced to my threshold. I had not heard
of powder-bound support, but it sounds like electrostatic binding. I wish
not to count on veil support. Instead, since I plan to avoid chopped
fibers, approach a similar state while including the coiling of fibers . I
seek 'loft' which is a term used in down (as in goose) which is another
material I wish to be biomimetic with.

William Kaukler wrote:
I have searched for reference and handbook information (yes, google too)
describing the load behavior of randomly tangled wool-like fiber matte.
The
interest is to design a wool-like material for elastic constant and
stiffness depending on the materials properties, volume fraction and
geometry (fiber thickness, cross section, length) of the fibers
involved.
Materials will be inorganic fibers and not polymers or natural fibers.
Fibers will likely be curled or twisted and not straight. That should
not
constrain the governing equations. I have no idea what governing
equations
there may be. I expect there are empirical relations to use? There must
be
some engineering work from ancient subjects like pillow making, steel
wool,
filters or packaging. Fiber books don't cover this topic. No materials
books or chapters in them address such topics.
If there is a clue out there among you to resolve this, and you have
read
this far, then let me add further refinements. Say I want to make a
fibrous
matte much like Fiberfrax or the like. How might the mechanical
compressibility change if a heat treatment allows fiber interconnects to
form (sintering). Adhesives or sintering can ultimately make the matte
into
a rigid structure. I wish to control stiffness or the spring constant
but
maximize the compressed volume ratio. How would the properties change
if I
substituted sapphire fibers for silica glass for example?
A book, web site, name of subject area or good keyword is all I ask.

Prof. K

One of my favorite "lectures" is how much we materials science guy
jabbrer on about microstructure and material properties, and how little we

Your problem points it out quite nicely.

I came to this conclusion in studying the effects of porosity on
materials behavior.

First I concluded that we really didn't know what the heck porosity was.

I used open cell, closed cell and steel wool (actually plastic or metal
coil sink scrubber) materials to illustrate the point.

Secondly, I concluded that we often had no useful micromechanical or
microproperty theories...... and I used the same materials to illustrate
the point.

Dear Dr. K..... do you agree with this short summary?

Dr. Ashby hit the nail on the head in discussing mechanical applications
as:
1) Tension (Or compression)
2) Bending
3) Torsion

In the systems of loose fibers such as steel wool, the mechanisms of
bending and perhaps even torsion dominate the micromechanical behavior.
This gives great softness or high compliance because of "lever" like
effects.

Eventually you can fill the voids enough that the compression response
of the matrix becomes dominant.

Or you can cross bond or cross link the filaments enough that eventually
the compression or tension modes of the fibers become dominant.

Theory sucks in understanding this.... and most other porosity effects,
except for the trivial.

Jim Buch



--
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I have searched for reference and handbook information (yes, google too)
describing the load behavior of randomly tangled wool-like fiber matte. The
interest is to design a wool-like material for elastic constant and
stiffness depending on the materials properties, volume fraction and
geometry (fiber thickness, cross section, length) of the fibers involved.
Materials will be inorganic fibers and not polymers or natural fibers.
Fibers will likely be curled or twisted and not straight. That should not
constrain the governing equations. I have no idea what governing equations
there may be. I expect there are empirical relations to use? There must be
some engineering work from ancient subjects like pillow making, steel wool,
filters or packaging. Fiber books don't cover this topic. No materials
books or chapters in them address such topics.
If there is a clue out there among you to resolve this, and you have read
this far, then let me add further refinements. Say I want to make a fibrous
matte much like Fiberfrax or the like. How might the mechanical
compressibility change if a heat treatment allows fiber interconnects to
form (sintering). Adhesives or sintering can ultimately make the matte into
a rigid structure. I wish to control stiffness or the spring constant but
maximize the compressed volume ratio. How would the properties change if I
substituted sapphire fibers for silica glass for example?
A book, web site, name of subject area or good keyword is all I ask.

Prof. K

...
interest is to design a wool-like material for elastic constant and
stiffness depending on the materials properties, volume fraction and
geometry (fiber thickness, cross section, length) of the fibers involved.
Materials will be inorganic fibers and not polymers or natural fibers.
Fibers will likely be curled or twisted and not straight. That should not
constrain the governing equations. I have no idea what governing equations
there may be. ...