Thu, 14 Oct 2004 20:53:26 +0000 (UTC) Terry Harper wrote:

"Archimedes Plutonium" wrote in message
...

A weight test where a weight is placed in the middle of the board and
WhiteAsh
flexed off center by 145 mm and Hickory flexed 106 mm and Oak flexed 70
mm. So Oak
is clearly the strongest and not Hickory!

No, you've proved that Oak is the stiffest, not that it is the strongest.
You need to break the samples to find out which is strongest. A 4-point
bending test would be best.
--
Terry Harper

Is there a scientific definition of "strength" and "stiffness" where the two
concepts are clearly distinguished or are they a mix of one another?

For instance a bicycle tubing of aluminum versus steel where both hold up
weight but where the aluminum tubing is made oversized for stiffness. So now
if we add weight to these two bicycles and when they break do we call that
strength.

Another example is wire of steel or copper where they have stiffness
contrasts and they hold different weights before they break.

So is the concept of strength tantamount to the concept of " the point at
which it breaks under force"? So is the science concept of strength one and
the same as the point at which the item breaks.

I am not sure I want to break those boards.

Is there another test for strength other than breaking the boards?

I am not sure that strength as a concept is in isolation of other concepts.
So I wonder how many concepts relating to Strength there exists for wood? In
that stiffness is a dependent concept and Penetration is a dependent concept
of strength.

Come to think about it, if Breaking is tantamount to Strength then the
science concept of strength really is integral to the chemical bonds
involved. So that Chemical Bonds is responsible to strength and that to find
out which is stronger WhiteOak or Hickory we must analyze their chemical
bonds atom by atom.

And maybe I should be looking into the chemical bonds of oak wood compared
to hickory. Whether there are more powerful bonds in oak versus hickory.
Perhaps oak is stronger than hickory because it has more covalent bonds and
less hydrogen bonds than does hickory.

Has anyone done a chemistry analysis of oak wood versus hickory as per
chemical bonds. Stronger bonds would be those with fewer impurities.

As anything in science, the more you dig deeper, the more a ocean of new
things
opens up.

Archimedes Plutonium
www.iw.net/~a_plutonium
whole entire Universe is just one big atom where dots
of the electron-dot-cloud are galaxies

On Thu, 14 Oct 2004 22:36:41 -0500, Archimedes Plutonium
wrote:

Thu, 14 Oct 2004 20:53:26 +0000 (UTC) Terry Harper wrote:

"Archimedes Plutonium" wrote in message
...

A weight test where a weight is placed in the middle of the board and
WhiteAsh
flexed off center by 145 mm and Hickory flexed 106 mm and Oak flexed 70
mm. So Oak
is clearly the strongest and not Hickory!

No, you've proved that Oak is the stiffest, not that it is the strongest.
You need to break the samples to find out which is strongest. A 4-point
bending test would be best.
--
Terry Harper

Is there a scientific definition of "strength" and "stiffness" where the two
concepts are clearly distinguished or are they a mix of one another?

For instance a bicycle tubing of aluminum versus steel where both hold up
weight but where the aluminum tubing is made oversized for stiffness. So now
if we add weight to these two bicycles and when they break do we call that
strength.

Another example is wire of steel or copper where they have stiffness
contrasts and they hold different weights before they break.

So is the concept of strength tantamount to the concept of " the point at
which it breaks under force"? So is the science concept of strength one and
the same as the point at which the item breaks.

I am not sure I want to break those boards.

Is there another test for strength other than breaking the boards?

I am not sure that strength as a concept is in isolation of other concepts.
So I wonder how many concepts relating to Strength there exists for wood? In
that stiffness is a dependent concept and Penetration is a dependent concept
of strength.

Come to think about it, if Breaking is tantamount to Strength then the
science concept of strength really is integral to the chemical bonds
involved. So that Chemical Bonds is responsible to strength and that to find
out which is stronger WhiteOak or Hickory we must analyze their chemical
bonds atom by atom.

And maybe I should be looking into the chemical bonds of oak wood compared
to hickory. Whether there are more powerful bonds in oak versus hickory.
Perhaps oak is stronger than hickory because it has more covalent bonds and
less hydrogen bonds than does hickory.

Has anyone done a chemistry analysis of oak wood versus hickory as per
chemical bonds. Stronger bonds would be those with fewer impurities.

As anything in science, the more you dig deeper, the more a ocean of new
things
opens up.

Archimedes Plutonium
www.iw.net/~a_plutonium
whole entire Universe is just one big atom where dots
of the electron-dot-cloud are galaxies



Different kinds of strength are shown here.

http://www-materials.eng.cam.ac.uk/m...c/IEChart.html
--

- Charles
-
-does not play well with others

Fri, 15 Oct 2004 03:53:30 GMT Charles wrote:



Different kinds of strength are shown here.

http://www-materials.eng.cam.ac.uk/m...c/IEChart.html
--

I was unable to get that site.

But I wonder if anyone has offered a math equation for stiffness of wood in relation
to strength of wood.

If not, then this science area has been neglected and very shabby.

If someone has attempted to relate stiffness to strength of wood then this area of
science has received due diligence.

On Sun, 24 Oct 2004 03:15:45 -0500, Archimedes Plutonium
wrote:

Fri, 15 Oct 2004 03:53:30 GMT Charles wrote:



Different kinds of strength are shown here.

http://www-materials.eng.cam.ac.uk/m...c/IEChart.html
--

I was unable to get that site.

This one may be more easily accessible:

http://www.fpl.fs.fed.us/documnts/pdf2001/green01d.pdf

But I wonder if anyone has offered a math equation for stiffness of wood in relation
to strength of wood.

The PDF cited above includes an adequate review of the mathematics of
the many stiffness and strength properties that are used to describe
wood.

Some important points to get from reading that document:

Wood is orthotropic: its properties are unique and independent in each
of the Cartesian axes and in each shear plane. These properties are
very different from species to species, and not all properties vary in
the same direction.

There are standard measures of these properties, and there are
standard methods of measure. In the U.S., the procedures are given in
ASTM D143, which any library at an institution with a materials
science program should have.

Stiffness, or rigidity, denotes elastic resistance to deformation: it
applies at loads insufficient to cause permanent deformation or
fracture. Strength denotes resistance to loads that cause permanent
(plastic) deformation or failure.

The two are correlated, but the correlation is only moderate; there is
nothing like an equation relating stiffness and strength, nor could
there possibly be: the physical mechanisms at work in elastic
deformation and plastic deformation of wood are quite different.

For example, two important structural woods, Loblolly Pine and Red
Oak, differ to quite different degrees in stiffness and strength. They
are practically equal in stiffness: modulus of elasticity in bending
for Red Oak is 12.5 GPa; for Loblolly Pine, it is 12.3 GPa. But Red
Oak is noticeably stronger than Loblolly Pine: modulus of rupture in
bending is 99 MPa for Red Oak, but 88 MPa for Loblolly Pine. However,
Loblolly Pine is stronger in another important measu modulus of
rupture in compression: 49.2 MPa vs. 46.6 MPa. And if you are not yet
adequately convinced that there is no exact relation, note that Yellow
Poplar, a relatively weak wood in most other properties, is far
stronger than either in tension parallel to grain: 154.4 MPa vs. 101.4
MPa for Red Oak.

If not, then this science area has been neglected and very shabby.

No, it has been well understood for hundreds or thousands of years.
Mathematical development, of course, was possible only in the last few
centuries. But wood is such an important structural material that it
is not at all neglected. Any handbook of building materials and any
building code will have extensive data on the strength and permissible
loading of various types of wood.

If someone has attempted to relate stiffness to strength of wood then this area of
science has received due diligence.

As indeed it has, and has been for many years.

--
Chris Green

Archimedes Plutonium wrote:

Fri, 15 Oct 2004 03:53:30 GMT Charles wrote:



Different kinds of strength are shown here.

http://www-materials.eng.cam.ac.uk/m...c/IEChart.html
--


I was unable to get that site.

But I wonder if anyone has offered a math equation for stiffness of wood in relation
to strength of wood.

If not, then this science area has been neglected and very shabby.



You are a real idiot.

In general, strength is most often controlled by defect size and
additionally the theoretical treatments (going back to the 1920's) also
include elastic modulus (stiffness to you).

Something is indeed shabby here.

Knowledge? If non-zero.

If someone has attempted to relate stiffness to strength of wood then this area of
science has received due diligence.




--
................................


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Sun, 24 Oct 2004 09:20:41 GMT Christopher Green wrote:
(snipped)


This one may be more easily accessible:

http://www.fpl.fs.fed.us/documnts/pdf2001/green01d.pdf

But I wonder if anyone has offered a math equation for stiffness of wood in relation
to strength of wood.

The PDF cited above includes an adequate review of the mathematics of
the many stiffness and strength properties that are used to describe
wood.

Some important points to get from reading that document:

Wood is orthotropic: its properties are unique and independent in each
of the Cartesian axes and in each shear plane. These properties are
very different from species to species, and not all properties vary in
the same direction.

There are standard measures of these properties, and there are
standard methods of measure. In the U.S., the procedures are given in
ASTM D143, which any library at an institution with a materials
science program should have.

Stiffness, or rigidity, denotes elastic resistance to deformation: it
applies at loads insufficient to cause permanent deformation or
fracture. Strength denotes resistance to loads that cause permanent
(plastic) deformation or failure.

The two are correlated, but the correlation is only moderate; there is
nothing like an equation relating stiffness and strength, nor could
there possibly be: the physical mechanisms at work in elastic
deformation and plastic deformation of wood are quite different.

For example, two important structural woods, Loblolly Pine and Red
Oak, differ to quite different degrees in stiffness and strength. They
are practically equal in stiffness: modulus of elasticity in bending
for Red Oak is 12.5 GPa; for Loblolly Pine, it is 12.3 GPa. But Red
Oak is noticeably stronger than Loblolly Pine: modulus of rupture in
bending is 99 MPa for Red Oak, but 88 MPa for Loblolly Pine. However,
Loblolly Pine is stronger in another important measu modulus of
rupture in compression: 49.2 MPa vs. 46.6 MPa. And if you are not yet
adequately convinced that there is no exact relation, note that Yellow
Poplar, a relatively weak wood in most other properties, is far
stronger than either in tension parallel to grain: 154.4 MPa vs. 101.4
MPa for Red Oak.

If not, then this science area has been neglected and very shabby.

No, it has been well understood for hundreds or thousands of years.
Mathematical development, of course, was possible only in the last few
centuries. But wood is such an important structural material that it
is not at all neglected. Any handbook of building materials and any
building code will have extensive data on the strength and permissible
loading of various types of wood.

That is a good website. It may have answered a question brewing in my mind as to whether
green treated lumber was stonger than untreated. Since wet lumber is weaker than dry, I
suspect green-treated or pressure treated is weaker than untreated, but do not hold me to
that speculation.

That website would have hit the jackpot for me if it had included the data on Hickory,
White Ash, White Oak, BlueSpruce and Honeylocust.

Because, if you remember, I hold a grudge between the acclaimed strength of Hickory
versus WhiteOak and the **obvious observation of the growth pattern of these trees**. The
growth of WhiteOak allows for the limbs to be parrallel to the ground whereas Hickory is
upward. That spooky oak look of whiteoak. So the wood would have to be **super strong**
to hold that weight.

So I need to see some data, Chris, that reconciles the obvious fact that WhiteOak is able
to throw limbs out parallel to the ground and hold them there whereas Hickory throws its
limbs upward.

That report has a reference to a science lab in Pennsylvania. Perhaps they ran hickory
and whiteoak and whiteash through their labs?

I need to see the data that will reconcile the observation of Whiteoak limbs parallel to
ground whereas hickory opts out for a weaker profile.

And while I am at it, I need to reconcile the fact that BlueSpruce foliage is so dense
yet able to withstand winds must translate into a superior strong wood compared to many
others. Again, another reconciliation of observation to numbers data.

So can you provide another website that has those numbers for Hickory, WhiteOak,
WhiteAsh, Locust and BlueSpruce.

Archimedes Plutonium
www.iw.net/~a_plutonium
whole entire Universe is just one big atom where dots
of the electron-dot-cloud are galaxies

Archimedes Plutonium wrote in message ...
What prompted this question? Well recently I bought some lumber of white
ash, plus hickory plus white oak and various others. I do not believe
the data on strength of wood is accurate and am wanting to test these
woods myself. I believe oak is stronger than hickory. I believe the
strength of hickory is a sales hype. The reason I say this is because in
history trebuchets were built out of oak and not hickory even though
England had hickory species and ash species. And because the growth
pattern of oaks allows horizontal branches which means the wood has to
be tougher and stronger to grow horizontal. I also want to test spruce
for strength because a spruce bears the full force of wind so its wood
must be strong.


........................snip...................... ........

Arch,
Think first. Oaks grow larger than ash and hickory and therefore
were better suited to the construction of trebuchets, and houses
and ships for that matter.
Testament to the strength of hickory and ash can be found in the
traditional preference for these woods in axe handles and carriage
frames. (High strength - low weight applications.)
BTW. Spruce is preferred for aircraft structure due to its high
strength to weight ratio, by dimensional size it is not too strong
and quite soft compared to denser woods.
Always look for the wisdom inherent in empirical data, it just needs
to be interpreted.

pragmatist.

"While you struggle to cram Theory into your head,
Practice sneaks up and bites you on the ass."