Real life statics question help

Hello all, it has been a while since I took statics, so I am hoping someone can help me out with this real life problem.

Let's say that I have a curved, solid, cylindrical piece of steel that is about 2 inches in diameter and about 1 foot long. On one side it is attached to something that can be considered as fixed and on the other side, there is a 400 pound weight.

If I want to add a v-notch to this piece of steel, so that it fractures as the weight bounces up and down, where would be the best place to add the notch? I was thinking the best place would be at the bottom of the curve where both sides start coming back up, but wasn't sure.

Here's a rough MS Paint picture and a real picture showing said piece of steel. Thank you.

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Put the notch on the tension side, where it will be the initiator of a crack. That means it goes on the top.

[COLOR=#333333]where it will be the initiator of a crack. That means it goes on the top.[/COLOR]