Dynamic modeling deinonychosaur claws

[Phil Bigelow <bigelowp@juno.com>]

All well and good.  But note that my question was about the relative
*strength* of a curved blade compared to a straight blade with the same
cutting surface length.  In particular, the relative susceptibilities of
each to torsional stresses and the relative shear strengths of each.

On straight blades, the tip is far from the "pivot point" (aka, the
articular surface).  On a strongly curved blade with the same cutting
surface length, the tip is closer to the pivot point.  This gives the
curved blade less leverage, but possibly greater strength.  For both
dinosaur predators and knife users, this may be a worthwhile tradeoff.

It may be useful to computer model and then test the relative shear
strengths and torsional strengths of the curved pedal unguals of various
curved-claw predatory dinosaurs.  It would be valuable to know the
absolute maximum amount of force that each species' unguals can take
before they break.  Test for maximum sagital force, maximum lateral
force, and maximum twisting force.  Even knowing the maximum compressive
force may prove informative.

<pb>
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On Wed, 02 Nov 2005 15:31:56 -0500 Michael Habib <mhabib5@jhmi.edu>
writes:
> Well, two comments on curvature and cutting surface:
> 
> 1) The cutting surface would only be increased in length if the claw 
> 
> were curved in the other direction (recurved).
> 
> 2) The concept of a curved edge (be it a claw, tooth, sword, etc) 
> adding appreciably to total cutting power by adding edge length is 
> something of an urban legend.  The total amount of 'added edge' is 
> pretty minor.  Curved edges have advantages, but cutting is not one 
> of 
> them.  A straight edge cuts just as well.  (I, personally, was quite 
> 
> surprised to learn this little tidbit).
> 
> Cheers,
> --Mike
> 
> On Wednesday, November 2, 2005, at 02:04 PM, Phil Bigelow wrote:
> 
> > No one has mentioned the relative shear strengths of long 
> straight
> > unguals vs long curved unguals.  With a curved claw, the cutting 
> > surface
> > length can be quite long, yet the entire claw is shorter overall.
> >
> > All other things being equal, could curved cutting surfaces be 
> less 
> > prone
> > to breakage than straight cutting surfaces with the same blade 
> length?
> >
> > <pb>
> 
> 


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