Materials Science C

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Briscon
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Re: Materials Science C

Postby Briscon » February 5th, 2013, 8:03 am

I'm curious , what was the lab at the Regional Competition?
At most invitationals, I have not seen a lab and it has been only a paper test (not entirely within the spirit of the rules for the event).
When I ran it at the Northview competition, the lab portion involved measuring and plotting Young's Modulus using the cantilever method.

I'm just worried, unless event supervisors figure out some associated labs, this event will end up being only a paper test.
I would also like to know what other have done since I will run this event 2 more times this season.
I've done two competitions so far, both invitationals, with labs. At the first, I constructed the different crystal structures using Styrofoam balls and toothpicks, and created a stress-strain curve measuring the deflection of a wire that was stretched taught between two ring stands. At the second, I had compare (not measure) contact angles of four different liquids(distilled water, vegetable oil, motor oil, and one other) on three different surfaces (plastic, glass, and metal). I also had to compare various properties, such as ductility and fracture toughness, of three materials (silly putty, modeling clay, and play dough).

Some labs will have you use equations for the various material characterization techniques, like the one with the wire above, which uses Young's modulus. The second lab would have been almost impossible to get accurate, repeatable results, so it focused on the comparison between them rather than a calculation. Usually, you will be able to piece together what to do in a lab if you have a solid knowledge of all the physical and chemical characterization techniques.

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Re: Materials Science C

Postby andrewwski » February 5th, 2013, 11:29 am

Supervised this event at a regional competition over the weekend - some advice and things to know based on the most common mistakes:

-Young's Modulus is a function of stress and strain. Stress is force/area and force is mass*acceleration. Strain is the change in length/original length. Stress does not have units of mass, and strain does not have units of distance. The other way around is not true either! You should know the units for stress and strain (or that strain doesn't have one)!
-When a term such as creep is defined for you, pay attention! If you didn't measure it correctly, or used the wrong units, that's easy points you lost! Read every question.
-Material classes - know how to classify items into them. Many teams got most of these wrong - know the difference between the material types, and common materials that fall into each.
-Crystal structures - the event specs specifically mention packing factor - so it'd be a good idea to know the common ones, and where they come from.

And general test taking tips - if it's multiple choice and there's no penalty for guessing...write down an answer! You'd think it'd be obvious, but more than one team left several multiple choice questions blank.
I'm curious , what was the lab at the Regional Competition?
At most invitationals, I have not seen a lab and it has been only a paper test (not entirely within the spirit of the rules for the event).
When I ran it at the Northview competition, the lab portion involved measuring and plotting Young's Modulus using the cantilever method.

I'm just worried, unless event supervisors figure out some associated labs, this event will end up being only a paper test.
I would also like to know what other have done since I will run this event 2 more times this season.
I'll post the test/lab up on the Test Exchange on Sunday, as there are some other New York regions that may be using similar questions this weekend.

I agree that it's a rather difficult event to come up with good labs for that produce quality data without the need for expensive supplies and equipment. I would say the bulk of the event ended up being a paper test - I had two experiments, but the theory and data collection behind them was so basic that the bulk of the points lied in the data analysis - which would have worked just as well by providing the data. Compared to many other lab events, I feel the quality and feasibility of traditional "lab" experiments is limited.

A lot of the suggested experiments available from national or state resources focus on using non-Newtonian substances (Silly Putty, Play-Doh, etc) to measure properties such as Young's Modulus, strength, etc. But I don't like this. These materials do not behave like typical elastic materials - properties such as Young's Modulus, ultimate strength, etc, are dependent on the strain rate. This is not indicative of the behavior of typical materials, and can get really confusing and inconsistent when typical experiments to measure these properties are performed.

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Re: Materials Science C

Postby chalker7 » February 5th, 2013, 12:02 pm

A lot of the suggested experiments available from national or state resources focus on using non-Newtonian substances (Silly Putty, Play-Doh, etc) to measure properties such as Young's Modulus, strength, etc. But I don't like this. These materials do not behave like typical elastic materials - properties such as Young's Modulus, ultimate strength, etc, are dependent on the strain rate. This is not indicative of the behavior of typical materials, and can get really confusing and inconsistent when typical experiments to measure these properties are performed.
That's fair, but just to be a devil's advocate, What constitutes a "typical" material? Every material has different and/or unique properties.
We suggested using soft malleable materials like those listed above to get the general idea across (demonstrating what stress, strain, etc are,) not necessarily to promote their utility as a comparison to elastic metals (or whatever you consider "typical.")
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Re: Materials Science C

Postby wlsguy » February 5th, 2013, 12:04 pm

Thanks for the experiment information.

I agree. Using Silly Puddy is not a substitute for an Instron.
But the pocket Instron hasn't been invented yet so we need to come up with alternatives

My experiment basically looked like the one shown here:
http://www.scribd.com/doc/32877284/Expe ... -s-Modulus

I made a few changes in that I provided:
The equation (without explaination of how to use it)
A more simplified setup that used 1/16" square balsa and Basswood as the test piece instead of the meter rule as well as all of the wood dimensions.
a set of weights with known values (5 washers on paper clips where each one weighed 3g)

The students were able to see the appropriate deflections, graph the deflection of both materials, and calculate the youngs modulus.
Since wood has a very small elastic region and I didn't want to make twice as many setups, I did not provide enough weight to test to failure.

I got the idea from the above experiment as well as the Balsa Spar Test jig used for Indoor models.
http://www.indoorduration.com/F1DPropConstruction.htm
Last edited by wlsguy on February 5th, 2013, 12:13 pm, edited 1 time in total.

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Re: Materials Science C

Postby chalker7 » February 5th, 2013, 12:13 pm

Thanks for the experiment information.

I agree. Using Silly Puddy is not a substitute for an Instron.
But the pocket Instron hasn't been invented yet so we need to come up with alternatives

My experiment basically looked like the one shown here:
http://www.scribd.com/doc/32877284/Expe ... -s-Modulus

I made a few changes in that I provided:
The equation (without explaination of how to use it)
A more simplified setup that used 1/16" square balsa and Basswood as the test piece instead of the meter rule as well as all of the wood dimensions.
a set of weights with known values (5 washers on paper clips where each one weighed 3g)

The students were able to see the appropriate deflections, graph the deflection of both materials, and calculate the youngs modulus.
Since wood has a very small elastic region and I didn't want to make twice as many setups, I did not provide enough weight to test to failure.

That seems like a totally reasonable experimental setup (and has a secondary benefit of training teams for how to accurately test their balsa for the structure events!)
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wlsguy
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Re: Materials Science C

Postby wlsguy » February 5th, 2013, 12:14 pm

I got the idea from an old Indoor duration article.
http://www.indoorduration.com/F1DPropConstruction.htm

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Re: Materials Science C

Postby RAntonello » February 11th, 2013, 2:50 pm

Supervised this event at a regional competition over the weekend - some advice and things to know based on the most common mistakes:

-Young's Modulus is a function of stress and strain. Stress is force/area and force is mass*acceleration. Strain is the change in length/original length. Stress does not have units of mass, and strain does not have units of distance. The other way around is not true either! You should know the units for stress and strain (or that strain doesn't have one)!
-When a term such as creep is defined for you, pay attention! If you didn't measure it correctly, or used the wrong units, that's easy points you lost! Read every question.
-Material classes - know how to classify items into them. Many teams got most of these wrong - know the difference between the material types, and common materials that fall into each.
-Crystal structures - the event specs specifically mention packing factor - so it'd be a good idea to know the common ones, and where they come from.

And general test taking tips - if it's multiple choice and there's no penalty for guessing...write down an answer! You'd think it'd be obvious, but more than one team left several multiple choice questions blank.
I'm curious , what was the lab at the Regional Competition?
At most invitationals, I have not seen a lab and it has been only a paper test (not entirely within the spirit of the rules for the event).
When I ran it at the Northview competition, the lab portion involved measuring and plotting Young's Modulus using the cantilever method.

I'm just worried, unless event supervisors figure out some associated labs, this event will end up being only a paper test.
I would also like to know what other have done since I will run this event 2 more times this season.
I'll post the test/lab up on the Test Exchange on Sunday, as there are some other New York regions that may be using similar questions this weekend.
Now that it's Monday, could you post the test/lab?

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Re: Materials Science C

Postby Shad160 » February 11th, 2013, 3:02 pm

^Eastern Long Island had their Regionals postponed by a couple of weeks due to the recent snow storm, so he may have to hold off for a while :(
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Re: Materials Science C

Postby andrewwski » February 14th, 2013, 4:29 pm

Yeah, I'm not sure if they are using any of the questions that I got sent from NYSSO or not. I'll post it after their regionals is over, or if I have the chance, I could post a partial test removing the questions that came from the state.

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Re: Materials Science C

Postby SaltyShampoo » February 16th, 2013, 1:46 pm

Is it a test or lab this year for regionals? Or a mixture of both? I was told it was just a series of labs accompanied by questions. I did not know that there was a written test as well. Sorry, this is my first year in Science Olympiad and I have no idea how this is going to work.


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