Carbon fiber bone plate

[robmit]

I am trying to make several carbon fiber/epoxy bone plates (fracture fixation devices) for some tests, but I am lost.
I have searched for a "recipe" to start with, but no avail.
I am interested in some basic information, like: how many plies are necessary, the resin/fiber ratio, the usual information to start with.
Any help, guidance, directions or informations would be appreciated (at least several articles, books, anything).
Thank you.

 

[RPstress]

Assuming a suitable resin can be found (I don't know which ones might be suitable for use in the body but the carbon itself is biocompatible, or so I have read) you could try taking the dimensions of a titanium or austenitic stainless steel part and duplicating the dimensions of that with a carbon/polymer laminate.

About 50 to 60% fiber by volume (30 to 40% resin by weight as a weight proportion of the final layup for epoxy or polyester resin) is usual. With this amount of fiber and resin, a ply having an areal mass of carbon of 250 grams per square meter should have a final thickness of about 0.25 mm (this dividing of the areal mass in gsm by 1000 to get the approximate ply thickness in mm works reasonably well for about 55% fiber volume).

The mechanical properties of a mixed layup (in terms of fiber directions) should have a similar stiffness and strength to most titanium alloys and a stiffness about half of annealed stainless steel (but a higher strength).

If you decide to use more resin, factor the thickness by the fiber volume used, so a 30% fiber volume (as opposed to 60%) laminate should start out roughly twice as thick as a titanium part doing the same job.

Note that any fasteners will be less strong in bearing than fasteners in titanium, roughly as strong as fasteners in alumium alloy, and probably similar in bearing strength to annealed stainless steel.

If you are going to use short fiber reinforced thermoplastic rather than a laminate try 40 to 50% carbon by volume and use at least double the thickness of stainless steel.

Although not affected much by mammalian body temperature there will be a small knock-down compared with room temperature tests, especially for fastener bearing.

 

[robmit]

Thank you for your advice.