So I ask my kid a simple question and the little brat lays Charpy/Izod impact testing on me.

[NNadir]

I was laying around last night, kind of goofing off, and I came across this paper: Elastic and electronic properties of TcB2 and superhard ReB2: First-principles calculations, Yuan Xu Wang, Appl. Phys. Lett. 91, 101904 (2007).

I'm going through the paper and I get to wondering, in a naïve kind of way, what the relationship between hardness and fracture resistance. So I say to myself, "Self, you could look it up, but it's late and you're supposed to do other things, so why not ask the little brat? He's educated and its easier than looking stuff up."

So I email him.

He emails back:

...Fracture resistance is really a measure of toughness though which depends on both the strength and ductility of the material. Hardness correlates pretty well with yield strength of a material but does not tend to say much about the ductility of the material, so it's somewhat impossible to predict a material's toughness simply from hardness measurements. To measure fracture resistance you would much rather want to perform tensile tests or Charpy/Izod impact testing. For some brittle ceramic materials you can also get some relevant information from 3-point or 4-point bend tests...

Charpy/Izod impact testing? Really?

Smart ass.

Don't you hate it when the little brats grow up to be smarter than you are?

Nah, I'm proud of him being smarter than his dumb old man, and someday I'll have to ask him what the hell Charpy/Izod impact testing is.

Or else I'll have to look it up.

Little brat...

[TexasTowelie]

1. I'm surprised that the smart son didn't include the three minute video with his email.

[NNadir]

4. Thanks. Now I don't have to look it up. The little brat could have said...

..."the swingy hammer thingy..."

[captain queeg]

2. We had to run these kinds of tests in "Busting lab"

In Materials when we studied those charts for different kind of steels (I think of phase dyagrams, but I’m pretty sure that’s not the right term), but I do remember the prof talking about “toughness” where they talked about strain-rate dependance . He commented how they developed steels for tanks with extremely high toughness

But that was 40 yrs ago and I doubt that would be worth the expense, not being effective again modern
Shaped charges.

[regnaD kciN]

3. Isn't an Izod test...

...where you see whether a crocodile can break it?