Sharpness and tip profile effects on stab penetration (reference)

Cliff:

Interesting piece. Comes as no surprise that the "dagger" shape wins the penetration test. I'd read somewhere that skin is actually pretty tough but that once holed a blade would meet lesser resistance to penetration. The authors come up with an interesting "double" bump theory on penetration - sounds reasonable considering the mechanics of a hand powered bladed attack. I also hadn't thought about the "lubricating" effects of blood on penetration.
 
Interesting paper.

My favorite part was on page 3, where they describe the anti-suction effect of fullers on knives! hehe
 
I have personally found the geometry and sharpness of the blade's very tip (i.e. 'pointiness') to be the overwhelming factor in a blade's stabbing ability. The difference between a more blunt profile such as a drop point, and a pointed profile like a Sheffield style Bowie, is almost unbelievable. Of course you'd think there would be a difference, but few people realize just how huge of a difference there is. It can mean having to put your wieght into it and really pushing, or the knife practically sliding in under its own weight.

Also, false edges (preferable sharpened) on the spine make a really big difference. What you do with a sharpening stone at the point also plays a big role. Not just sharpening, but shaping.
 
Thomas J Ekman :

How did you stumble upon this information?
Click to expand...

I was discussing the surface properties of thin crystal films with someone working in the field. When my interest was explained (the behavior of knife edges - the intersection of two surfaces), he pointed out some people who do work that might be of interest.

-Cliff
 
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