where are the weak points/stress risers on your knives?

[hardheart]

I can't see the transition to the tang on a few of my knives, but the Hobbit Warrior is the only one where I'd be bothered if it broke-there's only a couple others with hidden tangs, and they're cheap

I have 3 folders with opening holes, an 806, Skirmish, and cobalt Boye. I guess the Skirmish is the worst off, with 4 holes in the blade.

I thought of this after seeing the Airkat threads being bumped, plus there's a thread in reviews about the Boker reality folder, with a groove cut in it for gauging stabbing depth

 

[ginshun]

I can't say as though I remember my FEA classes all that well, but I doubt that round holes in the blade would cause enough of a stress riser to be of significant worry. Especially since I believe that most knives with holes in the blades are designed with this in mind.

Even if the holes were square or triangular (sharp coners) I still doubt that it would be enough of a stress concentration to be concerned about, unless you are subjecting your knives to some major loading.

I know that people on the board have waved Spyderco's by cutting a portion of the blade out to open up the hole, and I don't recall anybody ever breaking the blades of them. It seems that Spyderco or somebody may have even tested this, and even with the hole opened up the blade was still sufficiently strong to be used without worry.

 

[orthogonal1]

I don't think the stress a knife sees along the plane of the blades width is the major issue, it is lateral (prying) and twisting loads that create the problems.

There are books that provide factors for determining the reduced strength that various shapes create in materials. The factors are usually modeled on imperical observations.

Then, too, the surface finish of any features needs to be considered. Rougher finish results in more stress risers in an already increased stress area.

I've seen a couple of knives that had snapped blades at the thumbstud. One, a Kershaw (not a low quality maker), snapped trimming plasterboard. Thumbstud hole + torsional/side load = reduced strength and breakage.