Pressure (Continued)

Now to continue the exciting analysis of what happens to a single bone cell as the front hoof of the two year old German horse Overdose strikes the surface of the race track, keeping in mind that the term bone cell covers a lot of territory in terms of the various cellular and molecular structures in the cannon bone.

Last post contained various matrix's, organic and inorganic, which illustrate the links or connections between bone materials microscopically. Then the question, when concussive or compressive force applies what precisely occurs? For our traveling horse we postulate that such forces come from all directions and that they are other than uniform.

But, the effect of any particular strain or force will work differently depending whether its:

1. a cell of collagen
2. calcified mineral lattice, or
3. the proteins of the bone glue.

For the bone glue proteins, below:
we may presume flexibility to the point of rubberiness. Materials science uses the term "ductile" as a synonym for malleable, and we know from Hansma's work these are characteristics of sacrificial bonds at work which lengthen and contract, ie. give, in response to stress.

I am supposing however, that concussive forces coming up from the track, and compressive forces coming down from the weight of the horse, mostly compress, squeeze or pressure proteins of the types illustrated above. Since the links are ductile instead of brittle one may presume them squeezing together in the manner of the springs of a mattress, as they are hit about 60 times with each change of lead. Whether any of the links will break or tear will be the next discussion.

As to the collagen fibrils that are encased by a mineral coat, I'm supposing very little happens here except again that they might be contracted somewhat to the extent permitted by the mineral coating around them. Without sufficient force--science calls it "critical strain"--I'm assuming very little happens to the collagen that comprises the larger volume of the total bone.

The unknown and concern is what happens to the mineral lattice in this process that is made of of calcium, phosphates and various other inorganic materials in smaller amounts which are more akin to solid rock than rubber.

For this I had to again google for some mechanical engineering stuff for this seems critical to me: what happens to the mineral lattice in the bone as the horse breezes?

Can e.g. the mineral lattice be squeezed in the manner of the organic material, or does it just hold solid and then break, shear or tear when we exceed critical strain?

Here are some relevant illustration of what we're looking at:

Ice crystals:
Glass crystals:
Rock:
An illustrations of atoms layers in a crystal:
Another illustration of a crystal:

Bang the above against a track surface 130 times at 12,000 lbs/sq. inch and what happens?

Some interesting terminology from Ceramics science:

Shear mode

Tear mode

Ductility--materials can be deformed without fracture.

the brittle-ductile transition zone

the stress intensity factor

the stability of the crack--cracks in the material are ok as long as they remain stable.

the energy release rate--

fracture resistance decreases as the number of thermal cycles increases

I'll try to put together some conclusions next post.

Training:
This post will mark the transition to making a separate training post for the particular day, which I'll continue below.