Stress Risers?

[shpshooter]

I thought I would post this as a thread, since I think it would be answered better.
In the broken CS Recon Scout thread it was mentioned that a lot of production knives have the weakness of having a "stress riser" from the factory which could cause the knife to break prematurely under stress.

Too bad so many production knives feature sharp corners (stress risers) where the tang leaves the blade proper -- a well-known design weakness. How serious can a design be if it intentionally includes such a defect?

I'm still a bit confused on this point. Does my Benchmade Nimravus/Nim Cub or my Benchmade Activator suffer from this? Can someone post a picture showing exactly what is meant by this? Thanks!

 

[mete]

Good design does not have sharp inner radii. If the radius at the junction of the back of the blade and tang is small it concentrates the stresses and invites fatigue and impact failure . In my career I've seen a huge number of failures caused by stress concentrations from poor design. Though the problem has been known for many years they still do it !!!

 

[george tichbourne]

The term stress riser simply means a place where stress cracks can begin.

The inside corner at the blade/handle junction was sharp and from this sharp corner a stress crack began and the breakage followed. The hammering simply speeded up the process.

When I make a knife destined for heavy use I try to avoid building in points where stress cracks can easily start, sometimes it is possible to reduce the stress points by incorporating a large radius then transitioning from a wide blade to a narrower handle tang.

 

[Will P.]

No, BM knives do not have stress risers. All the inner corners have been properly faired.