What Would You Do?

[gradenG]

Hi guys, long time lurker, first time poster here. I have a few questions/thoughts that I would love to run by the minds here on the science forums. 

 

I am working on a project that involves very thin wood rings. These are rings for your finger, so as you can imagine they are fairly fragile. My question is a two parter:

 

How can I test the force required to break the ring? I know the properties of the woods involved, as well as the dimensions. I am testing some methods to make the rings more durable (hopefully) and I want to chart my progress. Any thoughts for how to gauge the durability would be greatly appreciated. (Literally think of it as a wedding band, made of wood, consider the grain of the wood as well) 

 

My second question, what is going to be the best way to reinforce a circle, from the outside, inside, or from within? 

 

My apologies if my questions sound unclear, but I appreciate any thoughts or opinions you are able to offer. 

 

Cheers,

 

G

[pzkpfw]

I'd hang rings on a string, with the grain at 45 degrees off horizontal.

 

Then hang a large drink (pop?) bottle off the ring. Use increasing amounts of water in the bottle to provide a repeatable breaking force, that you can then see increases as you make the rings stronger.

 

Later testing could be done of compression testing (would be mechanically harder to rig up), and with different grain angles.

[pzkpfw]

For later bending and compression testing I'd get two long flat boards. Mount a hinge at one of the short ends, so the boards are connected, if you lay one board flat on a table, the other board can move up and down at one end.

 

Have the top board slightly longer, so with the whole thing on a table, the top board is over the edge of the table, so you can hang that bottle off it to provide weight.

 

Under the top board, near the free end, mount a bit of "T" shaped aluminium, the idea being to provide a narrow-width object that the top board presses down with.

 

Make two small blocks to hold rings. One with a slot, so the ring stands up on its edge. One with a wide gap so the ring is held flat, by its edges.

 

Now, you can place rings, at various grain angles, in a holder that you place near the end of the bottom board. The top board presses down on the ring (with that "T") - in one of two modes (flat, or against circumference).

 

You can then repeatably/measurably test strength by seeing how much water you can hang off the top board until a ring breaks.

[pzkpfw]

 

(Maybe the two boards are the same length, but the top board and hinge are mounted in a bit from the end of the bottom board.

 

That provides the overhang, and the bottom board has some free space to provide secure mounting (maybe just a counter weight to stop the test weight making the whole thing fall off the table.))

[gradenG]

Thank you Pzkpfw, I appreciate your response. That actually sounds like a really good idea, as I need to test both scenarios. I will set this up tomorrow at the shop possibly post picks of my progress.

 

Thanks again :)

 

G