Testing Apparatus

yousef213
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Re: Testing Apparatus

Post by yousef213 » February 28th, 2011, 4:11 pm

Well, unless you have a very unusual design, the force will go theough the 4 legs of your chimney, each holding about 3.75 kg (assuming you hold all the weight) then all the weight will be Transferred to the base, then to the ground.

So if your chimney if weak it wont get to the base, and if the base is weak, it wont be transferred to the ground.

Either case will result in premature failure.

So, the answer is BOTH THE CHIMNEY ANDTHE BASE NEED TO SUPPORT 15 KG ON THEIR OWN

That is one possible reason of why the chimney may feel very solid alone, but when attached, the structure itself feels weaker.
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Re: Testing Apparatus

Post by TYG » March 6th, 2011, 12:38 pm

Anyone know which states use BBs for tower testing? Also, why are BBs used instead of sand in some regional/state competitions?
Shouldn't the material they use to load the tower be kept constant, especially if sand is being used at the National tournament? In the rules for towers, it states,
The Event Supervisor provides the assessment devices, testing apparatus, hardware, and clean, dry sand or similar dry, free-flowing material (referred to subsequently as "sand").

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Re: Testing Apparatus

Post by smartkid222 » March 6th, 2011, 2:36 pm

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Re: Testing Apparatus

Post by rjm » March 6th, 2011, 2:58 pm

The wording in the rules was carefully chosen to permit use of various materials of loading structures, including BBs, sand, anything which is reasonably fine and flows smoothly without clumping or delivering noticeable impact loading to the structure. We call it all "sand" to make the rules read easily. The smooth, steady addition of load to the structure is more important than the particular material used.

At Nationals, we use Lake Michigan beach sand from a sand mine near Grand Haven, which has been cleaned, dried, sieved, and processed to remove carbonates and dust (it's processed to be foundry sand). We will not be using BBs. We think the sand flows smoothly and provides a steady-state load after the flow has begun, plus it's easy to clean up if someone kicks a bucket over.

Bob Monetza
Grand Haven, MI

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Re: Testing Apparatus

Post by TYG » March 6th, 2011, 3:07 pm

Okay, thank you for your explanation.

Also, is steadying the bucket allowed when testing the tower? Last year, two fingers (or something like that) were allowed, but I don't think it is stated anywhere in the rules.

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Re: Testing Apparatus

Post by AlphaTauri » March 7th, 2011, 12:41 pm

I do hope that they would let you steady the bucket...imo, towers are more likely to tip than bridges (especially C towers, with the proportionally longer chimneys) and there were certainly enough bridge tip-overs at competitions last year.
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Re: Testing Apparatus

Post by TYG » March 7th, 2011, 12:56 pm

Is there anything stated about it on the national website, in case for some reason they don't allow you? Rather than having people try to argue it without basis, a concrete rule or statement could solve everything.
Thanks.

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